Merge pull request #8947 from influxdata/sgc-explain

EXPLAIN ANALYZE implementation

Godeps

@@ -20,5 +20,6 @@ github.com/spaolacci/murmur3 0d12bf811670bf6a1a63828dfbd003eded177fce
 github.com/tinylib/msgp ad0ff2e232ad2e37faf67087fb24bf8d04a8ce20
 github.com/uber-go/atomic 74ca5ec650841aee9f289dce76e928313a37cbc6
 github.com/uber-go/zap fbae0281ffd546fa6d1959fec6075ac5da7fb577
+github.com/xlab/treeprint 06dfc6fa17cdde904617990a0c2d89e3e332dbb3
 golang.org/x/crypto 9477e0b78b9ac3d0b03822fd95422e2fe07627cd
 golang.org/x/sys 062cd7e4e68206d8bab9b18396626e855c992658

LICENSE_OF_DEPENDENCIES.md

@@ -25,3 +25,4 @@
 - github.com/uber-go/zap [MIT LICENSE](https://github.com/uber-go/zap/blob/master/LICENSE.txt)
 - golang.org/x/crypto [BSD LICENSE](https://github.com/golang/crypto/blob/master/LICENSE)
 - jquery 2.1.4 [MIT LICENSE](https://github.com/jquery/jquery/blob/master/LICENSE.txt)
+- github.com/xlab/treeprint [MIT LICENSE](https://github.com/xlab/treeprint/blob/master/LICENSE)

coordinator/shard_mapper.go

@@ -1,6 +1,7 @@
 package coordinator
 
 import (
+	"context"
 	"io"
 	"time"
 
@@ -160,7 +161,7 @@ func (a *LocalShardMapping) MapType(m *influxql.Measurement, field string) influ
 	return typ
 }
 
-func (a *LocalShardMapping) CreateIterator(m *influxql.Measurement, opt query.IteratorOptions) (query.Iterator, error) {
+func (a *LocalShardMapping) CreateIterator(ctx context.Context, m *influxql.Measurement, opt query.IteratorOptions) (query.Iterator, error) {
 	source := Source{
 		Database:        m.Database,
 		RetentionPolicy: m.RetentionPolicy,
@@ -184,7 +185,7 @@ func (a *LocalShardMapping) CreateIterator(m *influxql.Measurement, opt query.It
 		inputs := make([]query.Iterator, 0, len(measurements))
 		if err := func() error {
 			for _, measurement := range measurements {
-				input, err := sg.CreateIterator(measurement, opt)
+				input, err := sg.CreateIterator(ctx, measurement, opt)
 				if err != nil {
 					return err
 				}
@@ -197,7 +198,7 @@ func (a *LocalShardMapping) CreateIterator(m *influxql.Measurement, opt query.It
 		}
 		return query.Iterators(inputs).Merge(opt)
 	}
-	return sg.CreateIterator(m.Name, opt)
+	return sg.CreateIterator(ctx, m.Name, opt)
 }
 
 func (a *LocalShardMapping) IteratorCost(m *influxql.Measurement, opt query.IteratorOptions) (query.IteratorCost, error) {

coordinator/shard_mapper_test.go

@@ -1,6 +1,7 @@
 package coordinator_test
 
 import (
+	"context"
 	"reflect"
 	"testing"
 	"time"
@@ -40,7 +41,7 @@ func TestLocalShardMapper(t *testing.T) {
 		}
 
 		var sh MockShard
-		sh.CreateIteratorFn = func(measurement string, opt query.IteratorOptions) (query.Iterator, error) {
+		sh.CreateIteratorFn = func(ctx context.Context, measurement string, opt query.IteratorOptions) (query.Iterator, error) {
 			if measurement != "cpu" {
 				t.Errorf("unexpected measurement: %s", measurement)
 			}
@@ -74,7 +75,7 @@ func TestLocalShardMapper(t *testing.T) {
 		t.Fatalf("unexpected number of shard mappings: %d", len(m.ShardMap))
 	}
 
-	if _, err := ic.CreateIterator(measurement, query.IteratorOptions{}); err != nil {
+	if _, err := ic.CreateIterator(context.Background(), measurement, query.IteratorOptions{}); err != nil {
 		t.Fatalf("unexpected error: %s", err)
 	}
 
@@ -97,7 +98,7 @@ func TestLocalShardMapper(t *testing.T) {
 		t.Fatalf("unexpected number of shard mappings: %d", len(m.ShardMap))
 	}
 
-	if _, err := ic.CreateIterator(measurement, query.IteratorOptions{}); err != nil {
+	if _, err := ic.CreateIterator(context.Background(), measurement, query.IteratorOptions{}); err != nil {
 		t.Fatalf("unexpected error: %s", err)
 	}
 }

coordinator/statement_executor.go

@@ -2,6 +2,7 @@ package coordinator
 
 import (
 	"bytes"
+	"context"
 	"errors"
 	"fmt"
 	"io"
@@ -14,6 +15,8 @@ import (
 	"github.com/influxdata/influxdb/influxql"
 	"github.com/influxdata/influxdb/models"
 	"github.com/influxdata/influxdb/monitor"
+	"github.com/influxdata/influxdb/pkg/tracing"
+	"github.com/influxdata/influxdb/pkg/tracing/fields"
 	"github.com/influxdata/influxdb/query"
 	"github.com/influxdata/influxdb/services/meta"
 	"github.com/influxdata/influxdb/tsdb"
@@ -56,7 +59,7 @@ type StatementExecutor struct {
 func (e *StatementExecutor) ExecuteStatement(stmt influxql.Statement, ctx query.ExecutionContext) error {
 	// Select statements are handled separately so that they can be streamed.
 	if stmt, ok := stmt.(*influxql.SelectStatement); ok {
-		return e.executeSelectStatement(stmt, &ctx)
+		return e.executeSelectStatement(context.Background(), stmt, &ctx)
 	}
 
 	var rows models.Rows
@@ -136,7 +139,11 @@ func (e *StatementExecutor) ExecuteStatement(stmt influxql.Statement, ctx query.
 		}
 		err = e.executeDropUserStatement(stmt)
 	case *influxql.ExplainStatement:
-		rows, err = e.executeExplainStatement(stmt, &ctx)
+		if stmt.Analyze {
+			rows, err = e.executeExplainAnalyzeStatement(stmt, &ctx)
+		} else {
+			rows, err = e.executeExplainStatement(stmt, &ctx)
+		}
 	case *influxql.GrantStatement:
 		if ctx.ReadOnly {
 			messages = append(messages, query.ReadOnlyWarning(stmt.String()))
@@ -401,17 +408,13 @@ func (e *StatementExecutor) executeDropUserStatement(q *influxql.DropUserStateme
 	return e.MetaClient.DropUser(q.Name)
 }
 
-func (e *StatementExecutor) executeExplainStatement(q *influxql.ExplainStatement, ctx *query.ExecutionContext) (models.Rows, error) {
-	if q.Analyze {
-		return nil, errors.New("analyze is currently unimplemented")
-	}
-
+func (e *StatementExecutor) executeExplainStatement(q *influxql.ExplainStatement, ectx *query.ExecutionContext) (models.Rows, error) {
 	opt := query.SelectOptions{
-		InterruptCh: ctx.InterruptCh,
-		NodeID:      ctx.ExecutionOptions.NodeID,
+		InterruptCh: ectx.InterruptCh,
+		NodeID:      ectx.ExecutionOptions.NodeID,
 		MaxSeriesN:  e.MaxSelectSeriesN,
 		MaxBucketsN: e.MaxSelectBucketsN,
-		Authorizer:  ctx.Authorizer,
+		Authorizer:  ectx.Authorizer,
 	}
 
 	// Prepare the query for execution, but do not actually execute it.
@@ -437,6 +440,74 @@ func (e *StatementExecutor) executeExplainStatement(q *influxql.ExplainStatement
 	return models.Rows{row}, nil
 }
 
+func (e *StatementExecutor) executeExplainAnalyzeStatement(q *influxql.ExplainStatement, ectx *query.ExecutionContext) (models.Rows, error) {
+	stmt := q.Statement
+	t, span := tracing.NewTrace("select")
+	ctx := tracing.NewContextWithTrace(context.Background(), t)
+	ctx = tracing.NewContextWithSpan(ctx, span)
+	start := time.Now()
+
+	itrs, columns, err := e.createIterators(ctx, stmt, ectx)
+	if err != nil {
+		return nil, err
+	}
+
+	iterTime := time.Since(start)
+
+	// Generate a row emitter from the iterator set.
+	em := query.NewEmitter(itrs, stmt.TimeAscending(), ectx.ChunkSize)
+	em.Columns = columns
+	if stmt.Location != nil {
+		em.Location = stmt.Location
+	}
+	em.OmitTime = stmt.OmitTime
+	em.EmitName = stmt.EmitName
+
+	// Emit rows to the results channel.
+	var writeN int64
+	for {
+		var row *models.Row
+		row, _, err = em.Emit()
+		if err != nil {
+			goto CLEANUP
+		} else if row == nil {
+			// Check if the query was interrupted while emitting.
+			select {
+			case <-ectx.InterruptCh:
+				err = query.ErrQueryInterrupted
+				goto CLEANUP
+			default:
+			}
+			break
+		}
+
+		writeN += int64(len(row.Values))
+	}
+
+CLEANUP:
+	em.Close()
+	if err != nil {
+		return nil, err
+	}
+
+	totalTime := time.Since(start)
+	span.MergeFields(
+		fields.Duration("total_time", totalTime),
+		fields.Duration("planning_time", iterTime),
+		fields.Duration("execution_time", totalTime-iterTime),
+	)
+	span.Finish()
+
+	row := &models.Row{
+		Columns: []string{"EXPLAIN ANALYZE"},
+	}
+	for _, s := range strings.Split(t.Tree().String(), "\n") {
+		row.Values = append(row.Values, []interface{}{s})
+	}
+
+	return models.Rows{row}, nil
+}
+
 func (e *StatementExecutor) executeGrantStatement(stmt *influxql.GrantStatement) error {
 	return e.MetaClient.SetPrivilege(stmt.User, stmt.On, stmt.Privilege)
 }
@@ -469,14 +540,14 @@ func (e *StatementExecutor) executeSetPasswordUserStatement(q *influxql.SetPassw
 	return e.MetaClient.UpdateUser(q.Name, q.Password)
 }
 
-func (e *StatementExecutor) executeSelectStatement(stmt *influxql.SelectStatement, ctx *query.ExecutionContext) error {
-	itrs, columns, err := e.createIterators(stmt, ctx)
+func (e *StatementExecutor) executeSelectStatement(ctx context.Context, stmt *influxql.SelectStatement, ectx *query.ExecutionContext) error {
+	itrs, columns, err := e.createIterators(ctx, stmt, ectx)
 	if err != nil {
 		return err
 	}
 
 	// Generate a row emitter from the iterator set.
-	em := query.NewEmitter(itrs, stmt.TimeAscending(), ctx.ChunkSize)
+	em := query.NewEmitter(itrs, stmt.TimeAscending(), ectx.ChunkSize)
 	em.Columns = columns
 	if stmt.Location != nil {
 		em.Location = stmt.Location
@@ -501,7 +572,7 @@ func (e *StatementExecutor) executeSelectStatement(stmt *influxql.SelectStatemen
 		} else if row == nil {
 			// Check if the query was interrupted while emitting.
 			select {
-			case <-ctx.InterruptCh:
+			case <-ectx.InterruptCh:
 				return query.ErrQueryInterrupted
 			default:
 			}
@@ -518,13 +589,13 @@ func (e *StatementExecutor) executeSelectStatement(stmt *influxql.SelectStatemen
 		}
 
 		result := &query.Result{
-			StatementID: ctx.StatementID,
+			StatementID: ectx.StatementID,
 			Series:      []*models.Row{row},
 			Partial:     partial,
 		}
 
 		// Send results or exit if closing.
-		if err := ctx.Send(result); err != nil {
+		if err := ectx.Send(result); err != nil {
 			return err
 		}
 
@@ -538,12 +609,12 @@ func (e *StatementExecutor) executeSelectStatement(stmt *influxql.SelectStatemen
 		}
 
 		var messages []*query.Message
-		if ctx.ReadOnly {
+		if ectx.ReadOnly {
 			messages = append(messages, query.ReadOnlyWarning(stmt.String()))
 		}
 
-		return ctx.Send(&query.Result{
-			StatementID: ctx.StatementID,
+		return ectx.Send(&query.Result{
+			StatementID: ectx.StatementID,
 			Messages:    messages,
 			Series: []*models.Row{{
 				Name:    "result",
@@ -555,8 +626,8 @@ func (e *StatementExecutor) executeSelectStatement(stmt *influxql.SelectStatemen
 
 	// Always emit at least one result.
 	if !emitted {
-		return ctx.Send(&query.Result{
-			StatementID: ctx.StatementID,
+		return ectx.Send(&query.Result{
+			StatementID: ectx.StatementID,
 			Series:      make([]*models.Row, 0),
 		})
 	}
@@ -564,24 +635,24 @@ func (e *StatementExecutor) executeSelectStatement(stmt *influxql.SelectStatemen
 	return nil
 }
 
-func (e *StatementExecutor) createIterators(stmt *influxql.SelectStatement, ctx *query.ExecutionContext) ([]query.Iterator, []string, error) {
+func (e *StatementExecutor) createIterators(ctx context.Context, stmt *influxql.SelectStatement, ectx *query.ExecutionContext) ([]query.Iterator, []string, error) {
 	opt := query.SelectOptions{
-		InterruptCh: ctx.InterruptCh,
-		NodeID:      ctx.ExecutionOptions.NodeID,
+		InterruptCh: ectx.InterruptCh,
+		NodeID:      ectx.ExecutionOptions.NodeID,
 		MaxSeriesN:  e.MaxSelectSeriesN,
 		MaxBucketsN: e.MaxSelectBucketsN,
-		Authorizer:  ctx.Authorizer,
+		Authorizer:  ectx.Authorizer,
 	}
 
 	// Create a set of iterators from a selection.
-	itrs, columns, err := query.Select(stmt, e.ShardMapper, opt)
+	itrs, columns, err := query.Select(ctx, stmt, e.ShardMapper, opt)
 	if err != nil {
 		return nil, nil, err
 	}
 
 	if e.MaxSelectPointN > 0 {
 		monitor := query.PointLimitMonitor(itrs, query.DefaultStatsInterval, e.MaxSelectPointN)
-		ctx.Query.Monitor(monitor)
+		ectx.Query.Monitor(monitor)
 	}
 	return itrs, columns, nil
 }
@@ -1073,8 +1144,8 @@ func (e *StatementExecutor) NormalizeStatement(stmt influxql.Statement, defaultD
 		case *influxql.Measurement:
 			switch stmt.(type) {
 			case *influxql.DropSeriesStatement, *influxql.DeleteSeriesStatement:
-			// DB and RP not supported by these statements so don't rewrite into invalid
-			// statements
+				// DB and RP not supported by these statements so don't rewrite into invalid
+				// statements
 			default:
 				err = e.normalizeMeasurement(node, defaultDatabase)
 			}

coordinator/statement_executor_test.go

@@ -2,6 +2,7 @@ package coordinator_test
 
 import (
 	"bytes"
+	"context"
 	"errors"
 	"io"
 	"os"
@@ -50,7 +51,7 @@ func TestQueryExecutor_ExecuteQuery_SelectStatement(t *testing.T) {
 		}
 
 		var sh MockShard
-		sh.CreateIteratorFn = func(m string, opt query.IteratorOptions) (query.Iterator, error) {
+		sh.CreateIteratorFn = func(ctx context.Context, m string, opt query.IteratorOptions) (query.Iterator, error) {
 			return &FloatIterator{Points: []query.FloatPoint{
 				{Name: "cpu", Time: int64(0 * time.Second), Aux: []interface{}{float64(100)}},
 				{Name: "cpu", Time: int64(1 * time.Second), Aux: []interface{}{float64(200)}},
@@ -103,7 +104,7 @@ func TestQueryExecutor_ExecuteQuery_MaxSelectBucketsN(t *testing.T) {
 		}
 
 		var sh MockShard
-		sh.CreateIteratorFn = func(m string, opt query.IteratorOptions) (query.Iterator, error) {
+		sh.CreateIteratorFn = func(ctx context.Context, m string, opt query.IteratorOptions) (query.Iterator, error) {
 			return &FloatIterator{
 				Points: []query.FloatPoint{{Name: "cpu", Time: int64(0 * time.Second), Aux: []interface{}{float64(100)}}},
 			}, nil
@@ -384,7 +385,7 @@ func (s *TSDBStore) TagValues(_ query.Authorizer, database string, cond influxql
 type MockShard struct {
 	Measurements      []string
 	FieldDimensionsFn func(measurements []string) (fields map[string]influxql.DataType, dimensions map[string]struct{}, err error)
-	CreateIteratorFn  func(m string, opt query.IteratorOptions) (query.Iterator, error)
+	CreateIteratorFn  func(ctx context.Context, m string, opt query.IteratorOptions) (query.Iterator, error)
 	IteratorCostFn    func(m string, opt query.IteratorOptions) (query.IteratorCost, error)
 	ExpandSourcesFn   func(sources influxql.Sources) (influxql.Sources, error)
 }
@@ -417,8 +418,8 @@ func (sh *MockShard) MapType(measurement, field string) influxql.DataType {
 	return influxql.Unknown
 }
 
-func (sh *MockShard) CreateIterator(measurement string, opt query.IteratorOptions) (query.Iterator, error) {
-	return sh.CreateIteratorFn(measurement, opt)
+func (sh *MockShard) CreateIterator(ctx context.Context, measurement string, opt query.IteratorOptions) (query.Iterator, error) {
+	return sh.CreateIteratorFn(ctx, measurement, opt)
 }
 
 func (sh *MockShard) IteratorCost(measurement string, opt query.IteratorOptions) (query.IteratorCost, error) {

pkg/metrics/context.go

@@ -0,0 +1,20 @@
+package metrics
+
+import "context"
+
+type key int
+
+const (
+	groupKey key = iota
+)
+
+// NewContextWithGroup returns a new context with the given Group added.
+func NewContextWithGroup(ctx context.Context, c *Group) context.Context {
+	return context.WithValue(ctx, groupKey, c)
+}
+
+// GroupFromContext returns the Group associated with ctx or nil if no Group has been assigned.
+func GroupFromContext(ctx context.Context) *Group {
+	c, _ := ctx.Value(groupKey).(*Group)
+	return c
+}

pkg/metrics/counter.go

@@ -0,0 +1,28 @@
+package metrics
+
+import (
+	"strconv"
+	"sync/atomic"
+)
+
+// The Counter type represents a numeric counter that is safe to use from concurrent goroutines.
+type Counter struct {
+	val  int64
+	desc *desc
+}
+
+// Name identifies the name of the counter.
+func (c *Counter) Name() string { return c.desc.Name }
+
+// Value atomically returns the current value of the counter.
+func (c *Counter) Value() int64 { return atomic.LoadInt64(&c.val) }
+
+// Add atomically adds d to the counter.
+func (c *Counter) Add(d int64) { atomic.AddInt64(&c.val, d) }
+
+// String returns a string representation using the name and value of the counter.
+func (c *Counter) String() string {
+	var buf [16]byte
+	v := strconv.AppendInt(buf[:0], c.val, 10)
+	return c.desc.Name + ": " + string(v)
+}

pkg/metrics/counter_test.go

@@ -0,0 +1,14 @@
+package metrics
+
+import (
+	"testing"
+)
+
+func TestCounter_Add(t *testing.T) {
+	c := Counter{}
+	c.Add(5)
+	c.Add(5)
+	if exp, got := int64(10), c.Value(); exp != got {
+		t.Errorf("unexpected value; exp=%d, got=%d", exp, got)
+	}
+}

pkg/metrics/default_registry.go

@@ -0,0 +1,36 @@
+package metrics
+
+var defaultRegistry = NewRegistry()
+
+// MustRegisterGroup registers a new group using the specified name.
+// If the group name is not unique, MustRegisterGroup will panic.
+//
+// MustRegisterGroup is not safe to call from multiple goroutines.
+func MustRegisterGroup(name string) GID {
+	return defaultRegistry.MustRegisterGroup(name)
+}
+
+// MustRegisterCounter registers a new counter metric with the default registry
+// using the provided descriptor.
+// If the metric name is not unique, MustRegisterCounter will panic.
+//
+// MustRegisterCounter is not safe to call from multiple goroutines.
+func MustRegisterCounter(name string, opts ...descOption) ID {
+	return defaultRegistry.MustRegisterCounter(name, opts...)
+}
+
+// MustRegisterTimer registers a new timer metric with the default registry
+// using the provided descriptor.
+// If the metric name is not unique, MustRegisterTimer will panic.
+//
+// MustRegisterTimer is not safe to call from multiple goroutines.
+func MustRegisterTimer(name string, opts ...descOption) ID {
+	return defaultRegistry.MustRegisterTimer(name, opts...)
+}
+
+// NewGroup returns a new measurement group from the default registry.
+//
+// NewGroup is safe to call from multiple goroutines.
+func NewGroup(gid GID) *Group {
+	return defaultRegistry.NewGroup(gid)
+}

pkg/metrics/descriptors.go

@@ -0,0 +1,64 @@
+package metrics
+
+type groupDesc struct {
+	Name string
+	id   GID
+}
+
+type metricType int
+
+const (
+	counterMetricType metricType = iota
+	timerMetricType
+)
+
+type desc struct {
+	Name string
+	mt   metricType
+	gid  GID
+	id   ID
+}
+
+type descOption func(*desc)
+
+// WithGroup assigns the associated measurement to the group identified by gid originally
+// returned from MustRegisterGroup.
+func WithGroup(gid GID) descOption {
+	return func(d *desc) {
+		d.gid = gid
+	}
+}
+
+func newDesc(name string, opts ...descOption) *desc {
+	desc := &desc{Name: name}
+	for _, o := range opts {
+		o(desc)
+	}
+	return desc
+}
+
+const (
+	idMask   = (1 << 32) - 1
+	gidShift = 32
+)
+
+type (
+	GID uint32
+	ID  uint64
+)
+
+func newID(id int, gid GID) ID {
+	return ID(gid)<<gidShift + (ID(id) & idMask)
+}
+
+func (id ID) id() int {
+	return int(id & idMask)
+}
+
+func (id ID) gid() int {
+	return int(id >> gidShift)
+}
+
+func (id *ID) setGID(gid GID) {
+	*id |= ID(gid) << gidShift
+}

pkg/metrics/descriptors_test.go

@@ -0,0 +1,21 @@
+package metrics
+
+import (
+	"testing"
+
+	"github.com/influxdata/influxdb/pkg/testing/assert"
+)
+
+func TestID_newID(t *testing.T) {
+	var id = newID(0xff, 0xff0f0fff)
+	assert.Equal(t, id, ID(0xff0f0fff000000ff))
+	assert.Equal(t, id.id(), 0xff)
+	assert.Equal(t, id.gid(), 0xff0f0fff)
+}
+
+func TestID_setGID(t *testing.T) {
+	var id = ID(1)
+	assert.Equal(t, id.gid(), 0)
+	id.setGID(1)
+	assert.Equal(t, id.gid(), 1)
+}

pkg/metrics/doc.go

@@ -0,0 +1,6 @@
+/*
+Package metrics provides various measurements that are safe for concurrent access.
+
+Measurements are arranged into groups that are efficient to create and access.
+*/
+package metrics

pkg/metrics/group.go

@@ -0,0 +1,37 @@
+package metrics
+
+// The Group type represents an instance of a set of measurements that are used for
+// instrumenting a specific request.
+type Group struct {
+	g        *groupRegistry
+	counters []Counter
+	timers   []Timer
+}
+
+// Name returns the name of the group.
+func (g *Group) Name() string { return g.g.desc.Name }
+
+// GetCounter returns the counter identified by the id that was returned
+// by MustRegisterCounter for the same group.
+// Using an id from a different group will result in undefined behavior.
+func (g *Group) GetCounter(id ID) *Counter { return &g.counters[id.id()] }
+
+// GetTimer returns the timer identified by the id that was returned
+// by MustRegisterTimer for the same group.
+// Using an id from a different group will result in undefined behavior.
+func (g *Group) GetTimer(id ID) *Timer { return &g.timers[id.id()] }
+
+// The Metric type defines a Name
+type Metric interface {
+	Name() string
+}
+
+// ForEach calls fn for all measurements of the group.
+func (g *Group) ForEach(fn func(v Metric)) {
+	for i := range g.counters {
+		fn(&g.counters[i])
+	}
+	for i := range g.timers {
+		fn(&g.timers[i])
+	}
+}

pkg/metrics/group_registry.go

@@ -0,0 +1,79 @@
+package metrics
+
+import (
+	"fmt"
+	"sort"
+)
+
+// The groupRegistry type represents a set of metrics that are measured together.
+type groupRegistry struct {
+	desc        *groupDesc
+	descriptors []*desc
+	group       Group
+}
+
+func (g *groupRegistry) register(desc *desc) error {
+	p := sort.Search(len(g.descriptors), func(i int) bool {
+		return g.descriptors[i].Name == desc.Name
+	})
+
+	if p != len(g.descriptors) {
+		return fmt.Errorf("metric name '%s' already in use", desc.Name)
+	}
+
+	g.descriptors = append(g.descriptors, desc)
+	sort.Slice(g.descriptors, func(i, j int) bool {
+		return g.descriptors[i].Name < g.descriptors[j].Name
+	})
+
+	return nil
+}
+
+func (g *groupRegistry) mustRegister(desc *desc) {
+	if err := g.register(desc); err != nil {
+		panic(err.Error())
+	}
+}
+
+// MustRegisterCounter registers a new counter metric using the provided descriptor.
+// If the metric name is not unique, MustRegisterCounter will panic.
+//
+// MustRegisterCounter is not safe to call from multiple goroutines.
+func (g *groupRegistry) mustRegisterCounter(desc *desc) ID {
+	desc.mt = counterMetricType
+	g.mustRegister(desc)
+
+	desc.id = newID(len(g.group.counters), g.desc.id)
+	g.group.counters = append(g.group.counters, Counter{desc: desc})
+
+	return desc.id
+}
+
+// MustRegisterTimer registers a new timer metric using the provided descriptor.
+// If the metric name is not unique, MustRegisterTimer will panic.
+//
+// MustRegisterTimer is not safe to call from multiple goroutines.
+func (g *groupRegistry) mustRegisterTimer(desc *desc) ID {
+	desc.mt = timerMetricType
+	g.mustRegister(desc)
+
+	desc.id = newID(len(g.group.timers), g.desc.id)
+	g.group.timers = append(g.group.timers, Timer{desc: desc})
+
+	return desc.id
+}
+
+// newCollector returns a Collector with a copy of all the registered counters.
+//
+// newCollector is safe to call from multiple goroutines.
+func (g *groupRegistry) newGroup() *Group {
+	c := &Group{
+		g:        g,
+		counters: make([]Counter, len(g.group.counters)),
+		timers:   make([]Timer, len(g.group.timers)),
+	}
+	copy(c.counters, g.group.counters)
+	copy(c.timers, g.group.timers)
+
+	return c
+}

pkg/metrics/registry.go

@@ -0,0 +1,87 @@
+package metrics
+
+import (
+	"fmt"
+	"sort"
+)
+
+type Registry struct {
+	descriptors []*groupDesc
+	groups      []groupRegistry
+}
+
+const (
+	// DefaultGroup is the identifier for the default group.
+	DefaultGroup = GID(0)
+)
+
+// NewRegistry creates a new Registry with a single group identified by DefaultGroup.
+func NewRegistry() *Registry {
+	var r Registry
+	r.MustRegisterGroup("global")
+	return &r
+}
+
+func (r *Registry) register(gd *groupDesc) error {
+	p := sort.Search(len(r.descriptors), func(i int) bool {
+		return r.descriptors[i].Name == gd.Name
+	})
+
+	if p != len(r.descriptors) {
+		return fmt.Errorf("group name '%s' already in use", gd.Name)
+	}
+
+	r.descriptors = append(r.descriptors, gd)
+	sort.Slice(r.descriptors, func(i, j int) bool {
+		return r.descriptors[i].Name < r.descriptors[j].Name
+	})
+
+	gd.id = GID(len(r.groups))
+	r.groups = append(r.groups, groupRegistry{desc: gd})
+
+	return nil
+}
+
+func (r *Registry) mustRegister(gd *groupDesc) {
+	if err := r.register(gd); err != nil {
+		panic(err.Error())
+	}
+}
+
+// MustRegisterGroup registers a new group and panics if a group already exists with the same name.
+//
+// MustRegisterGroup is not safe to call from concurrent goroutines.
+func (r *Registry) MustRegisterGroup(name string) GID {
+	gd := &groupDesc{Name: name}
+	r.mustRegister(gd)
+	return gd.id
+}
+
+func (r *Registry) mustGetGroupRegistry(id GID) *groupRegistry {
+	if int(id) >= len(r.groups) {
+		panic(fmt.Sprintf("invalid group ID"))
+	}
+	return &r.groups[id]
+}
+
+// MustRegisterCounter registers a new counter metric using the provided descriptor.
+// If the metric name is not unique within the group, MustRegisterCounter will panic.
+//
+// MustRegisterCounter is not safe to call from concurrent goroutines.
+func (r *Registry) MustRegisterCounter(name string, opts ...descOption) ID {
+	desc := newDesc(name, opts...)
+	return r.mustGetGroupRegistry(desc.gid).mustRegisterCounter(desc)
+}
+
+// MustRegisterTimer registers a new timer metric using the provided descriptor.
+// If the metric name is not unique within the group, MustRegisterTimer will panic.
+//
+// MustRegisterTimer is not safe to call from concurrent goroutines.
+func (r *Registry) MustRegisterTimer(name string, opts ...descOption) ID {
+	desc := newDesc(name, opts...)
+	return r.mustGetGroupRegistry(desc.gid).mustRegisterTimer(desc)
+}
+
+func (r *Registry) NewGroup(gid GID) *Group {
+	return r.mustGetGroupRegistry(gid).newGroup()
+}

pkg/metrics/registry_test.go

@@ -0,0 +1,63 @@
+package metrics
+
+import (
+	"testing"
+
+	"github.com/influxdata/influxdb/pkg/testing/assert"
+)
+
+func TestRegistry_MustRegisterCounter(t *testing.T) {
+	r := NewRegistry()
+	id := r.MustRegisterCounter("counter")
+	assert.Equal(t, id, ID(0), "invalid id")
+}
+
+func TestRegistry_MustRegisterCounter_Panics(t *testing.T) {
+	r := NewRegistry()
+	r.MustRegisterCounter("counter")
+	assert.PanicsWithValue(t, "metric name 'counter' already in use", func() {
+		r.MustRegisterCounter("counter")
+	})
+}
+
+func TestRegistry_NewGroup_CounterIsZero(t *testing.T) {
+	r := NewRegistry()
+	id := r.MustRegisterCounter("counter")
+
+	c := r.NewGroup(DefaultGroup).GetCounter(id)
+	c.Add(1)
+	assert.Equal(t, int64(1), c.Value())
+
+	c = r.NewGroup(DefaultGroup).GetCounter(id)
+	assert.Equal(t, int64(0), c.Value())
+}
+
+func TestRegistry_MustRegisterTimer(t *testing.T) {
+	r := NewRegistry()
+	id := r.MustRegisterTimer("timer")
+	assert.Equal(t, ID(0), id, "invalid id")
+}
+
+func TestRegistry_MustRegisterTimer_Panics(t *testing.T) {
+	r := NewRegistry()
+	r.MustRegisterCounter("timer")
+	assert.PanicsWithValue(t, "metric name 'timer' already in use", func() {
+		r.MustRegisterCounter("timer")
+	})
+}
+
+func TestRegistry_MustRegisterMultiple(t *testing.T) {
+	r := NewRegistry()
+	cnt := r.MustRegisterCounter("counter")
+	tmr := r.MustRegisterTimer("timer")
+	assert.Equal(t, ID(0), cnt, "invalid id")
+	assert.Equal(t, ID(0), tmr, "invalid id")
+}
+
+func TestRegistry_MustRegister_Panics_Across_Measurements(t *testing.T) {
+	r := NewRegistry()
+	r.MustRegisterCounter("foo")
+	assert.PanicsWithValue(t, "metric name 'foo' already in use", func() {
+		r.MustRegisterCounter("foo")
+	})
+}

pkg/metrics/timer.go

@@ -0,0 +1,34 @@
+package metrics
+
+import (
+	"sync/atomic"
+	"time"
+)
+
+// The timer type is used to store a duration.
+type Timer struct {
+	val  int64
+	desc *desc
+}
+
+// Name returns the name of the timer.
+func (t *Timer) Name() string { return t.desc.Name }
+
+// Value atomically returns the value of the timer.
+func (t *Timer) Value() time.Duration { return time.Duration(atomic.LoadInt64(&t.val)) }
+
+// Update sets the timer value to d.
+func (t *Timer) Update(d time.Duration) { atomic.StoreInt64(&t.val, int64(d)) }
+
+// UpdateSince sets the timer value to the difference between since and the current time.
+func (t *Timer) UpdateSince(since time.Time) { t.Update(time.Since(since)) }
+
+// String returns a string representation using the name and value of the timer.
+func (t *Timer) String() string { return t.desc.Name + ": " + time.Duration(t.val).String() }
+
+// Time updates the timer to the duration it takes to call f.
+func (t *Timer) Time(f func()) {
+	s := time.Now()
+	f()
+	t.UpdateSince(s)
+}

pkg/metrics/timer_test.go

@@ -0,0 +1,14 @@
+package metrics
+
+import (
+	"testing"
+	"time"
+
+	"github.com/influxdata/influxdb/pkg/testing/assert"
+)
+
+func TestTimer_Update(t *testing.T) {
+	var c Timer
+	c.Update(100 * time.Millisecond)
+	assert.Equal(t, c.Value(), 100*time.Millisecond, "unexpected value")
+}

pkg/testing/assert/assertions.go

@@ -0,0 +1,96 @@
+package assert
+
+import (
+	"bytes"
+	"fmt"
+	"reflect"
+)
+
+type TestingT interface {
+	Helper()
+	Errorf(format string, args ...interface{})
+}
+
+// Equal asserts that the values are equal and returns
+// true if the assertion was successful.
+func Equal(t TestingT, got, expected interface{}, msgAndArgs ...interface{}) bool {
+	if ValuesAreEqual(got, expected) {
+		return true
+	}
+
+	t.Helper()
+	got, expected = formatValues(got, expected)
+	fail(t, fmt.Sprintf("Not Equal: got=%s, exp=%s", got, expected), msgAndArgs...)
+	return false
+}
+
+// NotEqual asserts that the values are not equal and returns
+// true if the assertion was successful.
+func NotEqual(t TestingT, got, expected interface{}, msgAndArgs ...interface{}) bool {
+	if !ValuesAreEqual(got, expected) {
+		return true
+	}
+
+	t.Helper()
+	_, expected = formatValues(got, expected)
+	fail(t, fmt.Sprintf("Equal: should not be %s", expected), msgAndArgs...)
+	return false
+}
+
+// PanicsWithValue asserts that fn panics, and that
+// the recovered panic value equals the expected panic value.
+//
+// Returns true if the assertion was successful.
+func PanicsWithValue(t TestingT, expected interface{}, fn PanicTestFunc, msgAndArgs ...interface{}) bool {
+	t.Helper()
+	if funcDidPanic, got := didPanic(fn); !funcDidPanic {
+		return fail(t, fmt.Sprintf("func %#v should panic\n\r\tPanic value:\t%v", fn, got), msgAndArgs...)
+	} else if got != expected {
+		return fail(t, fmt.Sprintf("func %#v should panic with value:\t%v\n\r\tPanic value:\t%v", fn, expected, got), msgAndArgs...)
+	}
+
+	return true
+}
+
+// ValuesAreEqual determines if the values are equal.
+func ValuesAreEqual(got, expected interface{}) bool {
+	if got == nil || expected == nil {
+		return got == expected
+	}
+
+	if exp, ok := expected.([]byte); ok {
+		act, ok := got.([]byte)
+		if !ok {
+			return false
+		} else if exp == nil || act == nil {
+			return exp == nil && act == nil
+		}
+		return bytes.Equal(exp, act)
+	}
+
+	return reflect.DeepEqual(expected, got)
+
+}
+
+// ValuesAreExactlyEqual determines if the values are equal and
+// their types are the same.
+func ValuesAreExactlyEqual(got, expected interface{}) bool {
+	if ValuesAreEqual(got, expected) {
+		return true
+	}
+
+	actualType := reflect.TypeOf(got)
+	if actualType == nil {
+		return false
+	}
+	expectedValue := reflect.ValueOf(expected)
+	if expectedValue.IsValid() && expectedValue.Type().ConvertibleTo(actualType) {
+		// Attempt comparison after type conversion
+		return reflect.DeepEqual(expectedValue.Convert(actualType).Interface(), got)
+	}
+
+	return false
+}
+
+// PanicTestFunc defines a function that is called to determine whether a panic occurs.
+type PanicTestFunc func()

pkg/testing/assert/doc.go

@@ -0,0 +1,4 @@
+/*
+Package assert provides helper functions that can be used with the standard Go testing package.
+*/
+package assert

pkg/testing/assert/helper.go

@@ -0,0 +1,53 @@
+package assert
+
+import (
+	"fmt"
+	"reflect"
+)
+
+func fail(t TestingT, failureMsg string, msgAndArgs ...interface{}) bool {
+	t.Helper()
+
+	msg := formatMsgAndArgs(msgAndArgs...)
+	if msg == "" {
+		t.Errorf("%s", failureMsg)
+	} else {
+		t.Errorf("%s: %s", failureMsg, msg)
+	}
+
+	return false
+}
+
+func formatValues(got, expected interface{}) (string, string) {
+	if reflect.TypeOf(got) != reflect.TypeOf(expected) {
+		return fmt.Sprintf("%T(%#v)", got, got), fmt.Sprintf("%T(%#v)", expected, expected)
+	}
+
+	return fmt.Sprintf("%#v", got), fmt.Sprintf("%#v", expected)
+}
+
+func formatMsgAndArgs(msgAndArgs ...interface{}) string {
+	if len(msgAndArgs) == 0 || msgAndArgs == nil {
+		return ""
+	}
+	if len(msgAndArgs) == 1 {
+		return msgAndArgs[0].(string)
+	}
+	if len(msgAndArgs) > 1 {
+		return fmt.Sprintf(msgAndArgs[0].(string), msgAndArgs[1:]...)
+	}
+	return ""
+}
+
+// didPanic returns true if fn panics when called.
+func didPanic(fn PanicTestFunc) (panicked bool, message interface{}) {
+	defer func() {
+		if message = recover(); message != nil {
+			panicked = true
+		}
+	}()
+
+	fn()
+
+	return panicked, message
+}

pkg/tracing/context.go

@@ -0,0 +1,32 @@
+package tracing
+
+import "context"
+
+type key int
+
+const (
+	spanKey key = iota
+	traceKey
+)
+
+// NewContextWithSpan returns a new context with the given Span added.
+func NewContextWithSpan(ctx context.Context, c *Span) context.Context {
+	return context.WithValue(ctx, spanKey, c)
+}
+
+// SpanFromContext returns the Span associated with ctx or nil if no Span has been assigned.
+func SpanFromContext(ctx context.Context) *Span {
+	c, _ := ctx.Value(spanKey).(*Span)
+	return c
+}
+
+// NewContextWithTrace returns a new context with the given Trace added.
+func NewContextWithTrace(ctx context.Context, t *Trace) context.Context {
+	return context.WithValue(ctx, traceKey, t)
+}
+
+// TraceFromContext returns the Trace associated with ctx or nil if no Trace has been assigned.
+func TraceFromContext(ctx context.Context) *Trace {
+	c, _ := ctx.Value(traceKey).(*Trace)
+	return c
+}

pkg/tracing/doc.go

@@ -0,0 +1,26 @@
+/*
+Package tracing provides a way for capturing hierarchical traces.
+
+To start a new trace with a root span named select
+
+    trace, span := tracing.NewTrace("select")
+
+It is recommended that a span be forwarded to callees using the
+context package. Firstly, create a new context with the span associated
+as follows
+
+	ctx = tracing.NewContextWithSpan(ctx, span)
+
+followed by calling the API with the new context
+
+	SomeAPI(ctx, ...)
+
+Once the trace is complete, it may be converted to a graph with the Tree method.
+
+	tree := t.Tree()
+
+The tree is intended to be used with the Walk function in order to generate
+different presentations. The default Tree#String method returns a tree.
+
+*/
+package tracing

pkg/tracing/fields/field.go

@@ -0,0 +1,117 @@
+package fields
+
+import (
+	"fmt"
+	"math"
+	"time"
+)
+
+type fieldType int
+
+const (
+	stringType fieldType = iota
+	boolType
+	int64Type
+	uint64Type
+	durationType
+	float64Type
+)
+
+// Field instances are constructed via Bool, String, and so on.
+//
+// "heavily influenced by" (i.e., partially stolen from)
+// https://github.com/opentracing/opentracing-go/log
+type Field struct {
+	key        string
+	fieldType  fieldType
+	numericVal int64
+	stringVal  string
+}
+
+// String adds a string-valued key:value pair to a Span.LogFields() record
+func String(key, val string) Field {
+	return Field{
+		key:       key,
+		fieldType: stringType,
+		stringVal: val,
+	}
+}
+
+// Bool adds a bool-valued key:value pair to a Span.LogFields() record
+func Bool(key string, val bool) Field {
+	var numericVal int64
+	if val {
+		numericVal = 1
+	}
+	return Field{
+		key:        key,
+		fieldType:  boolType,
+		numericVal: numericVal,
+	}
+}
+
+/// Int64 adds an int64-valued key:value pair to a Span.LogFields() record
+func Int64(key string, val int64) Field {
+	return Field{
+		key:        key,
+		fieldType:  int64Type,
+		numericVal: val,
+	}
+}
+
+// Uint64 adds a uint64-valued key:value pair to a Span.LogFields() record
+func Uint64(key string, val uint64) Field {
+	return Field{
+		key:        key,
+		fieldType:  uint64Type,
+		numericVal: int64(val),
+	}
+}
+
+// Uint64 adds a uint64-valued key:value pair to a Span.LogFields() record
+func Duration(key string, val time.Duration) Field {
+	return Field{
+		key:        key,
+		fieldType:  durationType,
+		numericVal: int64(val),
+	}
+}
+
+// Float64 adds a float64-valued key:value pair to a Span.LogFields() record
+func Float64(key string, val float64) Field {
+	return Field{
+		key:        key,
+		fieldType:  float64Type,
+		numericVal: int64(math.Float64bits(val)),
+	}
+}
+
+// Key returns the field's key.
+func (lf Field) Key() string {
+	return lf.key
+}
+
+// Value returns the field's value as interface{}.
+func (lf Field) Value() interface{} {
+	switch lf.fieldType {
+	case stringType:
+		return lf.stringVal
+	case boolType:
+		return lf.numericVal != 0
+	case int64Type:
+		return int64(lf.numericVal)
+	case uint64Type:
+		return uint64(lf.numericVal)
+	case durationType:
+		return time.Duration(lf.numericVal)
+	case float64Type:
+		return math.Float64frombits(uint64(lf.numericVal))
+	default:
+		return nil
+	}
+}
+
+// String returns a string representation of the key and value.
+func (lf Field) String() string {
+	return fmt.Sprint(lf.key, ": ", lf.Value())
+}

pkg/tracing/fields/fields.go

@@ -0,0 +1,61 @@
+package fields
+
+import "sort"
+
+type Fields []Field
+
+// Merge merges other with the current set, replacing any matching keys from other.
+func (fs *Fields) Merge(other Fields) {
+	var list []Field
+	i, j := 0, 0
+	for i < len(*fs) && j < len(other) {
+		if (*fs)[i].key < other[j].key {
+			list = append(list, (*fs)[i])
+			i++
+		} else if (*fs)[i].key > other[j].key {
+			list = append(list, other[j])
+			j++
+		} else {
+			// equal, then "other" replaces existing key
+			list = append(list, other[j])
+			i++
+			j++
+		}
+	}
+
+	if i < len(*fs) {
+		list = append(list, (*fs)[i:]...)
+	} else if j < len(other) {
+		list = append(list, other[j:]...)
+	}
+
+	*fs = list
+}
+
+// New creates a new set of fields, sorted by Key.
+// Duplicate keys are removed.
+func New(args ...Field) Fields {
+	fields := Fields(args)
+	sort.Slice(fields, func(i, j int) bool {
+		return fields[i].key < fields[j].key
+	})
+
+	// deduplicate
+	// loop invariant: fields[:i] has no duplicates
+	for i := 0; i < len(fields)-1; i++ {
+		j := i + 1
+		// find all duplicate keys
+		for j < len(fields) && fields[i].key == fields[j].key {
+			j++
+		}
+
+		d := (j - 1) - i // number of duplicate keys
+		if d > 0 {
+			// copy over duplicate keys in order to maintain loop invariant
+			copy(fields[i+1:], fields[j:])
+			fields = fields[:len(fields)-d]
+		}
+	}
+
+	return fields
+}

pkg/tracing/fields/fields_test.go

@@ -0,0 +1,101 @@
+package fields
+
+import (
+	"testing"
+
+	"github.com/influxdata/influxdb/pkg/testing/assert"
+)
+
+func makeFields(args ...string) Fields {
+	if len(args)%2 != 0 {
+		panic("uneven number of arguments")
+	}
+
+	var f Fields
+	for i := 0; i+1 < len(args); i += 2 {
+		f = append(f, String(args[i], args[i+1]))
+	}
+	return f
+}
+
+func TestNew(t *testing.T) {
+	cases := []struct {
+		n   string
+		l   []string
+		exp Fields
+	}{
+		{
+			n:   "empty",
+			l:   nil,
+			exp: makeFields(),
+		},
+		{
+			n:   "not duplicates",
+			l:   []string{"k01", "v01", "k03", "v03", "k02", "v02"},
+			exp: makeFields("k01", "v01", "k02", "v02", "k03", "v03"),
+		},
+		{
+			n:   "duplicates at end",
+			l:   []string{"k01", "v01", "k02", "v02", "k02", "v02"},
+			exp: makeFields("k01", "v01", "k02", "v02"),
+		},
+		{
+			n:   "duplicates at start",
+			l:   []string{"k01", "v01", "k02", "v02", "k01", "v01"},
+			exp: makeFields("k01", "v01", "k02", "v02"),
+		},
+		{
+			n:   "duplicates in middle",
+			l:   []string{"k01", "v01", "k02", "v02", "k03", "v03", "k02", "v02", "k02", "v02"},
+			exp: makeFields("k01", "v01", "k02", "v02", "k03", "v03"),
+		},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.n, func(t *testing.T) {
+			l := New(makeFields(tc.l...)...)
+			assert.Equal(t, tc.exp, l)
+		})
+	}
+}
+
+func TestFields_Merge(t *testing.T) {
+	cases := []struct {
+		n    string
+		l, r Fields
+		exp  Fields
+	}{
+		{
+			n:   "no matching keys",
+			l:   New(String("k05", "v05"), String("k03", "v03"), String("k01", "v01")),
+			r:   New(String("k02", "v02"), String("k04", "v04"), String("k00", "v00")),
+			exp: New(String("k05", "v05"), String("k03", "v03"), String("k01", "v01"), String("k02", "v02"), String("k04", "v04"), String("k00", "v00")),
+		},
+		{
+			n:   "multiple matching keys",
+			l:   New(String("k05", "v05"), String("k03", "v03"), String("k01", "v01")),
+			r:   New(String("k02", "v02"), String("k03", "v03a"), String("k05", "v05a")),
+			exp: New(String("k05", "v05a"), String("k03", "v03a"), String("k01", "v01"), String("k02", "v02")),
+		},
+		{
+			n:   "source empty",
+			l:   New(),
+			r:   New(String("k02", "v02"), String("k04", "v04"), String("k00", "v00")),
+			exp: New(String("k02", "v02"), String("k04", "v04"), String("k00", "v00")),
+		},
+		{
+			n:   "other empty",
+			l:   New(String("k02", "v02"), String("k04", "v04"), String("k00", "v00")),
+			r:   New(),
+			exp: New(String("k02", "v02"), String("k04", "v04"), String("k00", "v00")),
+		},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.n, func(t *testing.T) {
+			l := tc.l
+			l.Merge(tc.r)
+			assert.Equal(t, tc.exp, l)
+		})
+	}
+}

pkg/tracing/labels/labels.go

@@ -0,0 +1,74 @@
+package labels
+
+import "sort"
+
+type Label struct {
+	Key, Value string
+}
+
+// The Labels type represents a set of labels, sorted by Key.
+type Labels []Label
+
+// Merge merges other with the current set, replacing any matching keys from other.
+func (ls *Labels) Merge(other Labels) {
+	var list []Label
+	i, j := 0, 0
+	for i < len(*ls) && j < len(other) {
+		if (*ls)[i].Key < other[j].Key {
+			list = append(list, (*ls)[i])
+			i++
+		} else if (*ls)[i].Key > other[j].Key {
+			list = append(list, other[j])
+			j++
+		} else {
+			// equal, then "other" replaces existing key
+			list = append(list, other[j])
+			i++
+			j++
+		}
+	}
+
+	if i < len(*ls) {
+		list = append(list, (*ls)[i:]...)
+	} else if j < len(other) {
+		list = append(list, other[j:]...)
+	}
+
+	*ls = list
+}
+
+// New takes an even number of strings representing key-value pairs
+// and creates a new slice of Labels. Duplicates are removed, however,
+// there is no guarantee which will be removed
+func New(args ...string) Labels {
+	if len(args)%2 != 0 {
+		panic("uneven number of arguments to label.Labels")
+	}
+	var labels Labels
+	for i := 0; i+1 < len(args); i += 2 {
+		labels = append(labels, Label{Key: args[i], Value: args[i+1]})
+	}
+
+	sort.Slice(labels, func(i, j int) bool {
+		return labels[i].Key < labels[j].Key
+	})
+
+	// deduplicate
+	// loop invariant: labels[:i] has no duplicates
+	for i := 0; i < len(labels)-1; i++ {
+		j := i + 1
+		// find all duplicate keys
+		for j < len(labels) && labels[i].Key == labels[j].Key {
+			j++
+		}
+
+		d := (j - 1) - i // number of duplicate keys
+		if d > 0 {
+			// copy over duplicate keys in order to maintain loop invariant
+			copy(labels[i+1:], labels[j:])
+			labels = labels[:len(labels)-d]
+		}
+	}
+
+	return labels
+}

pkg/tracing/labels/labels_test.go

@@ -0,0 +1,101 @@
+package labels
+
+import (
+	"testing"
+
+	"github.com/influxdata/influxdb/pkg/testing/assert"
+)
+
+func makeLabels(args ...string) Labels {
+	if len(args)%2 != 0 {
+		panic("uneven number of arguments")
+	}
+
+	var l Labels
+	for i := 0; i+1 < len(args); i += 2 {
+		l = append(l, Label{Key: args[i], Value: args[i+1]})
+	}
+	return l
+}
+
+func TestNew(t *testing.T) {
+	cases := []struct {
+		n   string
+		l   []string
+		exp Labels
+	}{
+		{
+			n:   "empty",
+			l:   nil,
+			exp: makeLabels(),
+		},
+		{
+			n:   "not duplicates",
+			l:   []string{"k01", "v01", "k03", "v03", "k02", "v02"},
+			exp: makeLabels("k01", "v01", "k02", "v02", "k03", "v03"),
+		},
+		{
+			n:   "duplicates at end",
+			l:   []string{"k01", "v01", "k02", "v02", "k02", "v02"},
+			exp: makeLabels("k01", "v01", "k02", "v02"),
+		},
+		{
+			n:   "duplicates at start",
+			l:   []string{"k01", "v01", "k02", "v02", "k01", "v01"},
+			exp: makeLabels("k01", "v01", "k02", "v02"),
+		},
+		{
+			n:   "duplicates in middle",
+			l:   []string{"k01", "v01", "k02", "v02", "k03", "v03", "k02", "v02", "k02", "v02"},
+			exp: makeLabels("k01", "v01", "k02", "v02", "k03", "v03"),
+		},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.n, func(t *testing.T) {
+			l := New(tc.l...)
+			assert.Equal(t, l, tc.exp)
+		})
+	}
+}
+
+func TestLabels_Merge(t *testing.T) {
+	cases := []struct {
+		n    string
+		l, r Labels
+		exp  Labels
+	}{
+		{
+			n:   "no matching keys",
+			l:   New("k05", "v05", "k03", "v03", "k01", "v01"),
+			r:   New("k02", "v02", "k04", "v04", "k00", "v00"),
+			exp: New("k05", "v05", "k03", "v03", "k01", "v01", "k02", "v02", "k04", "v04", "k00", "v00"),
+		},
+		{
+			n:   "multiple matching keys",
+			l:   New("k05", "v05", "k03", "v03", "k01", "v01"),
+			r:   New("k02", "v02", "k03", "v03a", "k05", "v05a"),
+			exp: New("k05", "v05a", "k03", "v03a", "k01", "v01", "k02", "v02"),
+		},
+		{
+			n:   "source empty",
+			l:   New(),
+			r:   New("k02", "v02", "k04", "v04", "k00", "v00"),
+			exp: New("k02", "v02", "k04", "v04", "k00", "v00"),
+		},
+		{
+			n:   "other empty",
+			l:   New("k02", "v02", "k04", "v04", "k00", "v00"),
+			r:   New(),
+			exp: New("k02", "v02", "k04", "v04", "k00", "v00"),
+		},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.n, func(t *testing.T) {
+			l := tc.l
+			l.Merge(tc.r)
+			assert.Equal(t, l, tc.exp)
+		})
+	}
+}

pkg/tracing/rawspan.go

@@ -0,0 +1,18 @@
+package tracing
+
+import (
+	"time"
+
+	"github.com/influxdata/influxdb/pkg/tracing/fields"
+	"github.com/influxdata/influxdb/pkg/tracing/labels"
+)
+
+// RawSpan represents the data associated with a span.
+type RawSpan struct {
+	Context      SpanContext
+	ParentSpanID uint64        // ParentSpanID identifies the parent of this span or 0 if this is the root span.
+	Name         string        // Name is the operation name given to this span.
+	Start        time.Time     // Start identifies the start time of the span.
+	Labels       labels.Labels // Labels contains additional metadata about this span.
+	Fields       fields.Fields // Fields contains typed values associated with this span.
+}

pkg/tracing/span.go

@@ -0,0 +1,84 @@
+package tracing
+
+import (
+	"sync"
+	"time"
+
+	"github.com/influxdata/influxdb/pkg/tracing/fields"
+	"github.com/influxdata/influxdb/pkg/tracing/labels"
+)
+
+// The Span type denotes a specific operation for a Trace.
+// A Span may have one or more children, identifying additional
+// details about a trace.
+type Span struct {
+	tracer *Trace
+	mu     sync.Mutex
+	raw    RawSpan
+}
+
+type StartSpanOption interface {
+	applyStart(*Span)
+}
+
+// The StartTime start span option specifies the start time of
+// the new span rather than using now.
+type StartTime time.Time
+
+func (t StartTime) applyStart(s *Span) {
+	s.raw.Start = time.Time(t)
+}
+
+// StartSpan creates a new child span using time.Now as the start time.
+func (s *Span) StartSpan(name string, opt ...StartSpanOption) *Span {
+	return s.tracer.startSpan(name, s.raw.Context, opt)
+}
+
+// Context returns a SpanContext that can be serialized and passed to a remote node to continue a trace.
+func (s *Span) Context() SpanContext {
+	return s.raw.Context
+}
+
+// SetLabels replaces any existing labels for the Span with args.
+func (s *Span) SetLabels(args ...string) {
+	s.mu.Lock()
+	s.raw.Labels = labels.New(args...)
+	s.mu.Unlock()
+}
+
+// MergeLabels merges args with any existing labels defined
+// for the Span.
+func (s *Span) MergeLabels(args ...string) {
+	ls := labels.New(args...)
+	s.mu.Lock()
+	s.raw.Labels.Merge(ls)
+	s.mu.Unlock()
+}
+
+// SetFields replaces any existing fields for the Span with args.
+func (s *Span) SetFields(set fields.Fields) {
+	s.mu.Lock()
+	s.raw.Fields = set
+	s.mu.Unlock()
+}
+
+// MergeFields merges the provides args with any existing fields defined
+// for the Span.
+func (s *Span) MergeFields(args ...fields.Field) {
+	set := fields.New(args...)
+	s.mu.Lock()
+	s.raw.Fields.Merge(set)
+	s.mu.Unlock()
+}
+
+// Finish marks the end of the span and records it to the associated Trace.
+// If Finish is not called, the span will not appear in the trace.
+func (s *Span) Finish() {
+	s.mu.Lock()
+	s.tracer.addRawSpan(s.raw)
+	s.mu.Unlock()
+}
+
+func (s *Span) Tree() *TreeNode {
+	return s.tracer.TreeFrom(s.raw.Context.SpanID)
+}

pkg/tracing/spancontext.go

@@ -0,0 +1,27 @@
+package tracing
+
+import (
+	"github.com/gogo/protobuf/proto"
+	"github.com/influxdata/influxdb/pkg/tracing/wire"
+)
+
+// A SpanContext represents the minimal information to identify a span in a trace.
+// This is typically serialized to continue a trace on a remote node.
+type SpanContext struct {
+	TraceID uint64 // TraceID is assigned a random number to this trace.
+	SpanID  uint64 // SpanID is assigned a random number to identify this span.
+}
+
+func (s SpanContext) MarshalBinary() ([]byte, error) {
+	ws := wire.SpanContext(s)
+	return proto.Marshal(&ws)
+}
+
+func (s *SpanContext) UnmarshalBinary(data []byte) error {
+	var ws wire.SpanContext
+	err := proto.Unmarshal(data, &ws)
+	if err == nil {
+		*s = SpanContext(ws)
+	}
+	return err
+}

pkg/tracing/trace.go

@@ -0,0 +1,141 @@
+package tracing
+
+import (
+	"sort"
+	"sync"
+	"time"
+)
+
+// The Trace type functions as a container for capturing Spans used to
+// trace the execution of a request.
+type Trace struct {
+	mu    sync.Mutex
+	spans map[uint64]RawSpan
+}
+
+// NewTrace starts a new trace and returns a root span identified by the provided name.
+//
+// Additional options may be specified to override the default behavior when creating the span.
+func NewTrace(name string, opt ...StartSpanOption) (*Trace, *Span) {
+	t := &Trace{spans: make(map[uint64]RawSpan)}
+	s := &Span{tracer: t}
+	s.raw.Name = name
+	s.raw.Context.TraceID, s.raw.Context.SpanID = randomID2()
+	setOptions(s, opt)
+
+	return t, s
+}
+
+// NewTraceFromSpan starts a new trace and returns the associated span, which is a child of the
+// parent span context.
+func NewTraceFromSpan(name string, parent SpanContext, opt ...StartSpanOption) (*Trace, *Span) {
+	t := &Trace{spans: make(map[uint64]RawSpan)}
+	s := &Span{tracer: t}
+	s.raw.Name = name
+	s.raw.ParentSpanID = parent.SpanID
+	s.raw.Context.TraceID = parent.TraceID
+	s.raw.Context.SpanID = randomID()
+	setOptions(s, opt)
+
+	return t, s
+}
+
+func (t *Trace) startSpan(name string, sc SpanContext, opt []StartSpanOption) *Span {
+	s := &Span{tracer: t}
+	s.raw.Name = name
+	s.raw.Context.SpanID = randomID()
+	s.raw.Context.TraceID = sc.TraceID
+	s.raw.ParentSpanID = sc.SpanID
+	setOptions(s, opt)
+
+	return s
+}
+
+func setOptions(s *Span, opt []StartSpanOption) {
+	for _, o := range opt {
+		o.applyStart(s)
+	}
+
+	if s.raw.Start.IsZero() {
+		s.raw.Start = time.Now()
+	}
+}
+
+func (t *Trace) addRawSpan(raw RawSpan) {
+	t.mu.Lock()
+	t.spans[raw.Context.SpanID] = raw
+	t.mu.Unlock()
+}
+
+// Tree returns a graph of the current trace.
+func (t *Trace) Tree() *TreeNode {
+	t.mu.Lock()
+	defer t.mu.Unlock()
+
+	for _, s := range t.spans {
+		if s.ParentSpanID == 0 {
+			return t.treeFrom(s.Context.SpanID)
+		}
+	}
+	return nil
+}
+
+// Merge combines other with the current trace. This is
+// typically necessary when traces are transferred from a remote.
+func (t *Trace) Merge(other *Trace) {
+	for k, s := range other.spans {
+		t.spans[k] = s
+	}
+}
+
+func (t *Trace) TreeFrom(root uint64) *TreeNode {
+	t.mu.Lock()
+	defer t.mu.Unlock()
+	return t.treeFrom(root)
+}
+
+func (t *Trace) treeFrom(root uint64) *TreeNode {
+	c := map[uint64]*TreeNode{}
+
+	for k, s := range t.spans {
+		c[k] = &TreeNode{Raw: s}
+	}
+
+	if _, ok := c[root]; !ok {
+		return nil
+	}
+
+	for _, n := range c {
+		if n.Raw.ParentSpanID != 0 {
+			if pn := c[n.Raw.ParentSpanID]; pn != nil {
+				pn.Children = append(pn.Children, n)
+			}
+		}
+	}
+
+	// sort nodes
+	var v treeSortVisitor
+	Walk(&v, c[root])
+
+	return c[root]
+}
+
+type treeSortVisitor struct{}
+
+func (v *treeSortVisitor) Visit(node *TreeNode) Visitor {
+	sort.Slice(node.Children, func(i, j int) bool {
+		lt, rt := node.Children[i].Raw.Start.UnixNano(), node.Children[j].Raw.Start.UnixNano()
+		if lt < rt {
+			return true
+		} else if lt > rt {
+			return false
+		}
+
+		ln, rn := node.Children[i].Raw.Name, node.Children[j].Raw.Name
+		if ln < rn {
+			return true
+		}
+		return false
+	})
+	return v
+}

pkg/tracing/trace_encoding.go

@@ -0,0 +1,136 @@
+package tracing
+
+import (
+	"math"
+	"time"
+
+	"github.com/gogo/protobuf/proto"
+	"github.com/influxdata/influxdb/pkg/tracing/fields"
+	"github.com/influxdata/influxdb/pkg/tracing/labels"
+	"github.com/influxdata/influxdb/pkg/tracing/wire"
+)
+
+func fieldsToWire(set fields.Fields) []wire.Field {
+	var r []wire.Field
+	for _, f := range set {
+		wf := wire.Field{Key: f.Key()}
+		switch val := f.Value().(type) {
+		case string:
+			wf.FieldType = wire.FieldTypeString
+			wf.Value = &wire.Field_StringVal{StringVal: val}
+
+		case bool:
+			var numericVal int64
+			if val {
+				numericVal = 1
+			}
+			wf.FieldType = wire.FieldTypeBool
+			wf.Value = &wire.Field_NumericVal{NumericVal: numericVal}
+
+		case int64:
+			wf.FieldType = wire.FieldTypeInt64
+			wf.Value = &wire.Field_NumericVal{NumericVal: val}
+
+		case uint64:
+			wf.FieldType = wire.FieldTypeUint64
+			wf.Value = &wire.Field_NumericVal{NumericVal: int64(val)}
+
+		case time.Duration:
+			wf.FieldType = wire.FieldTypeDuration
+			wf.Value = &wire.Field_NumericVal{NumericVal: int64(val)}
+
+		case float64:
+			wf.FieldType = wire.FieldTypeFloat64
+			wf.Value = &wire.Field_NumericVal{NumericVal: int64(math.Float64bits(val))}
+
+		default:
+			continue
+		}
+
+		r = append(r, wf)
+	}
+	return r
+}
+
+func labelsToWire(set labels.Labels) []string {
+	var r []string
+	for i := range set {
+		r = append(r, set[i].Key, set[i].Value)
+	}
+	return r
+}
+
+func (t *Trace) MarshalBinary() ([]byte, error) {
+	wt := wire.Trace{}
+	for _, sp := range t.spans {
+		wt.Spans = append(wt.Spans, &wire.Span{
+			Context: wire.SpanContext{
+				TraceID: sp.Context.TraceID,
+				SpanID:  sp.Context.SpanID,
+			},
+			ParentSpanID: sp.ParentSpanID,
+			Name:         sp.Name,
+			Start:        sp.Start,
+			Labels:       labelsToWire(sp.Labels),
+			Fields:       fieldsToWire(sp.Fields),
+		})
+	}
+
+	return proto.Marshal(&wt)
+}
+
+func wireToFields(wfs []wire.Field) fields.Fields {
+	var fs []fields.Field
+	for _, wf := range wfs {
+		switch wf.FieldType {
+		case wire.FieldTypeString:
+			fs = append(fs, fields.String(wf.Key, wf.GetStringVal()))
+
+		case wire.FieldTypeBool:
+			var boolVal bool
+			if wf.GetNumericVal() != 0 {
+				boolVal = true
+			}
+			fs = append(fs, fields.Bool(wf.Key, boolVal))
+
+		case wire.FieldTypeInt64:
+			fs = append(fs, fields.Int64(wf.Key, wf.GetNumericVal()))
+
+		case wire.FieldTypeUint64:
+			fs = append(fs, fields.Uint64(wf.Key, uint64(wf.GetNumericVal())))
+
+		case wire.FieldTypeDuration:
+			fs = append(fs, fields.Duration(wf.Key, time.Duration(wf.GetNumericVal())))
+
+		case wire.FieldTypeFloat64:
+			fs = append(fs, fields.Float64(wf.Key, math.Float64frombits(uint64(wf.GetNumericVal()))))
+		}
+	}
+
+	return fields.New(fs...)
+}
+
+func (t *Trace) UnmarshalBinary(data []byte) error {
+	var wt wire.Trace
+	if err := proto.Unmarshal(data, &wt); err != nil {
+		return err
+	}
+
+	t.spans = make(map[uint64]RawSpan)
+
+	for _, sp := range wt.Spans {
+		t.spans[sp.Context.SpanID] = RawSpan{
+			Context: SpanContext{
+				TraceID: sp.Context.TraceID,
+				SpanID:  sp.Context.SpanID,
+			},
+			ParentSpanID: sp.ParentSpanID,
+			Name:         sp.Name,
+			Start:        sp.Start,
+			Labels:       labels.New(sp.Labels...),
+			Fields:       wireToFields(sp.Fields),
+		}
+	}
+
+	return nil
+}

pkg/tracing/tree.go

@@ -0,0 +1,74 @@
+package tracing
+
+import (
+	"github.com/xlab/treeprint"
+)
+
+// A Visitor's Visit method is invoked for each node encountered by Walk.
+// If the result of Visit is not nil, Walk visits each of the children.
+type Visitor interface {
+	Visit(*TreeNode) Visitor
+}
+
+// A TreeNode represents a single node in the graph.
+type TreeNode struct {
+	Raw      RawSpan
+	Children []*TreeNode
+}
+
+// String returns the tree as a string.
+func (t *TreeNode) String() string {
+	if t == nil {
+		return ""
+	}
+	tv := newTreeVisitor()
+	Walk(tv, t)
+	return tv.root.String()
+}
+
+// Walk traverses the graph in a depth-first order, calling v.Visit
+// for each node until completion or v.Visit returns nil.
+func Walk(v Visitor, node *TreeNode) {
+	if v = v.Visit(node); v == nil {
+		return
+	}
+
+	for _, c := range node.Children {
+		Walk(v, c)
+	}
+}
+
+type treeVisitor struct {
+	root  treeprint.Tree
+	trees []treeprint.Tree
+}
+
+func newTreeVisitor() *treeVisitor {
+	t := treeprint.New()
+	return &treeVisitor{root: t, trees: []treeprint.Tree{t}}
+}
+
+func (v *treeVisitor) Visit(n *TreeNode) Visitor {
+	t := v.trees[len(v.trees)-1].AddBranch(n.Raw.Name)
+	v.trees = append(v.trees, t)
+
+	if labels := n.Raw.Labels; len(labels) > 0 {
+		l := t.AddBranch("labels")
+		for _, ll := range n.Raw.Labels {
+			l.AddNode(ll.Key + ": " + ll.Value)
+		}
+	}
+
+	for _, k := range n.Raw.Fields {
+		t.AddNode(k.String())
+	}
+
+	for _, cn := range n.Children {
+		Walk(v, cn)
+	}
+
+	v.trees[len(v.trees)-1] = nil
+	v.trees = v.trees[:len(v.trees)-1]
+
+	return nil
+}

pkg/tracing/util.go

@@ -0,0 +1,26 @@
+package tracing
+
+import (
+	"math/rand"
+	"sync"
+	"time"
+)
+
+var (
+	seededIDGen  = rand.New(rand.NewSource(time.Now().UnixNano()))
+	seededIDLock sync.Mutex
+)
+
+func randomID() (n uint64) {
+	seededIDLock.Lock()
+	n = uint64(seededIDGen.Int63())
+	seededIDLock.Unlock()
+	return
+}
+
+func randomID2() (n uint64, m uint64) {
+	seededIDLock.Lock()
+	n, m = uint64(seededIDGen.Int63()), uint64(seededIDGen.Int63())
+	seededIDLock.Unlock()
+	return
+}

pkg/tracing/wire/binary.go

@@ -0,0 +1,7 @@
+/*
+Package wire is used to serialize a trace.
+
+*/
+package wire
+
+//go:generate protoc -I$GOPATH/src -I. --gogofaster_out=Mgoogle/protobuf/timestamp.proto=github.com/gogo/protobuf/types:. binary.proto

pkg/tracing/wire/binary.proto

@@ -0,0 +1,44 @@
+syntax = "proto3";
+package wire;
+
+import "github.com/gogo/protobuf/gogoproto/gogo.proto";
+import "google/protobuf/timestamp.proto";
+
+message SpanContext {
+  uint64 trace_id = 1 [(gogoproto.customname) = "TraceID"];
+  uint64 span_id = 2 [(gogoproto.customname) = "SpanID"];
+}
+
+message Span {
+  SpanContext context = 1 [(gogoproto.nullable) = false];
+  uint64 parent_span_id = 2 [(gogoproto.customname) = "ParentSpanID"];
+  string name = 3;
+  google.protobuf.Timestamp start_time = 4 [(gogoproto.customname) = "Start", (gogoproto.stdtime) = true, (gogoproto.nullable) = false];
+  repeated string labels = 5;
+  repeated Field fields = 6 [(gogoproto.nullable) = false];
+}
+
+message Trace {
+  repeated Span spans = 1;
+}
+
+message Field {
+  enum FieldType {
+    option (gogoproto.goproto_enum_prefix) = false;
+
+    STRING = 0 [(gogoproto.enumvalue_customname) = "FieldTypeString"];
+    BOOL = 1 [(gogoproto.enumvalue_customname) = "FieldTypeBool"];
+    INT_64 = 2 [(gogoproto.enumvalue_customname) = "FieldTypeInt64"];
+    UINT_64 = 3 [(gogoproto.enumvalue_customname) = "FieldTypeUint64"];
+    DURATION = 4 [(gogoproto.enumvalue_customname) = "FieldTypeDuration"];
+    FLOAT_64 = 6 [(gogoproto.enumvalue_customname) = "FieldTypeFloat64"];
+  }
+
+  string key = 1;
+  FieldType field_type = 2 [(gogoproto.customname) = "FieldType"];
+
+  oneof value {
+    sfixed64 numeric_val = 3 [(gogoproto.customname) = "NumericVal"];
+    string string_val = 4 [(gogoproto.customname) = "StringVal"];
+  }
+}

query/explain.go

@@ -2,6 +2,7 @@ package query
 
 import (
 	"bytes"
+	"context"
 	"fmt"
 	"io"
 	"strings"
@@ -13,7 +14,7 @@ func (p *preparedStatement) Explain() (string, error) {
 	// Determine the cost of all iterators created as part of this plan.
 	ic := &explainIteratorCreator{ic: p.ic}
 	p.ic = ic
-	itrs, _, err := p.Select()
+	itrs, _, err := p.Select(context.Background())
 	p.ic = ic.ic
 
 	if err != nil {
@@ -63,7 +64,7 @@ type explainIteratorCreator struct {
 	nodes []planNode
 }
 
-func (e *explainIteratorCreator) CreateIterator(m *influxql.Measurement, opt IteratorOptions) (Iterator, error) {
+func (e *explainIteratorCreator) CreateIterator(ctx context.Context, m *influxql.Measurement, opt IteratorOptions) (Iterator, error) {
 	cost, err := e.ic.IteratorCost(m, opt)
 	if err != nil {
 		return nil, err

query/internal/internal.pb.go

@@ -1,6 +1,5 @@
-// Code generated by protoc-gen-gogo.
+// Code generated by protoc-gen-gogo. DO NOT EDIT.
 // source: internal/internal.proto
-// DO NOT EDIT!
 
 /*
 Package query is a generated protocol buffer package.
@@ -48,6 +47,7 @@ type Point struct {
 	BooleanValue     *bool          `protobuf:"varint,10,opt,name=BooleanValue" json:"BooleanValue,omitempty"`
 	UnsignedValue    *uint64        `protobuf:"varint,12,opt,name=UnsignedValue" json:"UnsignedValue,omitempty"`
 	Stats            *IteratorStats `protobuf:"bytes,11,opt,name=Stats" json:"Stats,omitempty"`
+	Trace            []byte         `protobuf:"bytes,13,opt,name=Trace" json:"Trace,omitempty"`
 	XXX_unrecognized []byte         `json:"-"`
 }
 
@@ -140,6 +140,13 @@ func (m *Point) GetStats() *IteratorStats {
 	return nil
 }
 
+func (m *Point) GetTrace() []byte {
+	if m != nil {
+		return m.Trace
+	}
+	return nil
+}
+
 type Aux struct {
 	DataType         *int32   `protobuf:"varint,1,req,name=DataType" json:"DataType,omitempty"`
 	FloatValue       *float64 `protobuf:"fixed64,2,opt,name=FloatValue" json:"FloatValue,omitempty"`
@@ -537,54 +544,54 @@ func init() {
 func init() { proto.RegisterFile("internal/internal.proto", fileDescriptorInternal) }
 
 var fileDescriptorInternal = []byte{
-	// 769 bytes of a gzipped FileDescriptorProto
-	0x1f, 0x8b, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x02, 0xff, 0x8c, 0x55, 0xe1, 0x8e, 0xe3, 0x34,
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-	0x87, 0x99, 0xbb, 0x99, 0x87, 0xae, 0x22, 0x2d, 0xf7, 0xf8, 0xb0, 0x5c, 0xbb, 0xd3, 0x7b, 0xc2,
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-	0xb4, 0x84, 0x66, 0xcd, 0x28, 0xa6, 0x1c, 0x30, 0xf6, 0xbc, 0x7b, 0x5d, 0x80, 0x86, 0x82, 0xcd,
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-	0x00,
+	// 780 bytes of a gzipped FileDescriptorProto
+	0x1f, 0x8b, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x02, 0xff, 0x8c, 0x55, 0xdb, 0x6e, 0xe3, 0x36,
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+	0x13, 0xe9, 0x81, 0xdb, 0xef, 0xae, 0x5d, 0x49, 0x53, 0x81, 0x0d, 0x73, 0x38, 0xe0, 0xfc, 0x97,
+	0x83, 0x9d, 0xf1, 0x5c, 0x9d, 0xf1, 0xbd, 0x26, 0xa8, 0xcc, 0x80, 0x47, 0x7d, 0x8b, 0xc6, 0x7d,
+	0xcb, 0x17, 0x74, 0x7e, 0xf4, 0x3e, 0x61, 0xc3, 0x82, 0xba, 0x24, 0x34, 0x2c, 0x48, 0x7b, 0x49,
+	0x27, 0xf8, 0x8d, 0xb8, 0xef, 0x97, 0xf0, 0x28, 0xbf, 0xa2, 0x13, 0x3f, 0x91, 0x6e, 0x84, 0x1f,
+	0x65, 0x1d, 0xbe, 0x1d, 0x2e, 0xc4, 0xcf, 0x84, 0x7b, 0xc4, 0x22, 0x3f, 0x06, 0x2e, 0xfe, 0x37,
+	0x00, 0x00, 0xff, 0xff, 0x3d, 0xd1, 0x25, 0x7b, 0x8d, 0x06, 0x00, 0x00,
 }

query/internal/internal.proto

@@ -16,6 +16,7 @@ message Point {
     optional uint64 UnsignedValue = 12;
 
     optional IteratorStats Stats = 11;
+    optional bytes Trace = 13;
 }
 
 message Aux {

query/iterator.gen.go

@@ -8,8 +8,7 @@ package query
 
 import (
 	"container/heap"
-	"encoding/binary"
-	"fmt"
+	"context"
 	"io"
 	"sort"
 	"sync"
@@ -17,7 +16,6 @@ import (
 
 	"github.com/gogo/protobuf/proto"
 	"github.com/influxdata/influxdb/influxql"
-	internal "github.com/influxdata/influxdb/query/internal"
 )
 
 // DefaultStatsInterval is the default value for IteratorEncoder.StatsInterval.
@@ -3384,8 +3382,8 @@ type floatReaderIterator struct {
 }
 
 // newFloatReaderIterator returns a new instance of floatReaderIterator.
-func newFloatReaderIterator(r io.Reader, stats IteratorStats) *floatReaderIterator {
-	dec := NewFloatPointDecoder(r)
+func newFloatReaderIterator(ctx context.Context, r io.Reader, stats IteratorStats) *floatReaderIterator {
+	dec := NewFloatPointDecoder(ctx, r)
 	dec.stats = stats
 
 	return &floatReaderIterator{
@@ -6777,8 +6775,8 @@ type integerReaderIterator struct {
 }
 
 // newIntegerReaderIterator returns a new instance of integerReaderIterator.
-func newIntegerReaderIterator(r io.Reader, stats IteratorStats) *integerReaderIterator {
-	dec := NewIntegerPointDecoder(r)
+func newIntegerReaderIterator(ctx context.Context, r io.Reader, stats IteratorStats) *integerReaderIterator {
+	dec := NewIntegerPointDecoder(ctx, r)
 	dec.stats = stats
 
 	return &integerReaderIterator{
@@ -10170,8 +10168,8 @@ type unsignedReaderIterator struct {
 }
 
 // newUnsignedReaderIterator returns a new instance of unsignedReaderIterator.
-func newUnsignedReaderIterator(r io.Reader, stats IteratorStats) *unsignedReaderIterator {
-	dec := NewUnsignedPointDecoder(r)
+func newUnsignedReaderIterator(ctx context.Context, r io.Reader, stats IteratorStats) *unsignedReaderIterator {
+	dec := NewUnsignedPointDecoder(ctx, r)
 	dec.stats = stats
 
 	return &unsignedReaderIterator{
@@ -13549,8 +13547,8 @@ type stringReaderIterator struct {
 }
 
 // newStringReaderIterator returns a new instance of stringReaderIterator.
-func newStringReaderIterator(r io.Reader, stats IteratorStats) *stringReaderIterator {
-	dec := NewStringPointDecoder(r)
+func newStringReaderIterator(ctx context.Context, r io.Reader, stats IteratorStats) *stringReaderIterator {
+	dec := NewStringPointDecoder(ctx, r)
 	dec.stats = stats
 
 	return &stringReaderIterator{
@@ -16928,8 +16926,8 @@ type booleanReaderIterator struct {
 }
 
 // newBooleanReaderIterator returns a new instance of booleanReaderIterator.
-func newBooleanReaderIterator(r io.Reader, stats IteratorStats) *booleanReaderIterator {
-	dec := NewBooleanPointDecoder(r)
+func newBooleanReaderIterator(ctx context.Context, r io.Reader, stats IteratorStats) *booleanReaderIterator {
+	dec := NewBooleanPointDecoder(ctx, r)
 	dec.stats = stats
 
 	return &booleanReaderIterator{
@@ -16963,39 +16961,6 @@ func (itr *booleanReaderIterator) Next() (*BooleanPoint, error) {
 	return p, nil
 }
 
-// IteratorEncoder is an encoder for encoding an iterator's points to w.
-type IteratorEncoder struct {
-	w io.Writer
-
-	// Frequency with which stats are emitted.
-	StatsInterval time.Duration
-}
-
-// NewIteratorEncoder encodes an iterator's points to w.
-func NewIteratorEncoder(w io.Writer) *IteratorEncoder {
-	return &IteratorEncoder{
-		w: w,
-
-		StatsInterval: DefaultStatsInterval,
-	}
-}
-
-// EncodeIterator encodes and writes all of itr's points to the underlying writer.
-func (enc *IteratorEncoder) EncodeIterator(itr Iterator) error {
-	switch itr := itr.(type) {
-	case FloatIterator:
-		return enc.encodeFloatIterator(itr)
-	case IntegerIterator:
-		return enc.encodeIntegerIterator(itr)
-	case StringIterator:
-		return enc.encodeStringIterator(itr)
-	case BooleanIterator:
-		return enc.encodeBooleanIterator(itr)
-	default:
-		panic(fmt.Sprintf("unsupported iterator for encoder: %T", itr))
-	}
-}
-
 // encodeFloatIterator encodes all points from itr to the underlying writer.
 func (enc *IteratorEncoder) encodeFloatIterator(itr FloatIterator) error {
 	ticker := time.NewTicker(enc.StatsInterval)
@@ -17210,26 +17175,3 @@ func (enc *IteratorEncoder) encodeBooleanIterator(itr BooleanIterator) error {
 	}
 	return nil
 }
-
-// encode a stats object in the point stream.
-func (enc *IteratorEncoder) encodeStats(stats IteratorStats) error {
-	buf, err := proto.Marshal(&internal.Point{
-		Name: proto.String(""),
-		Tags: proto.String(""),
-		Time: proto.Int64(0),
-		Nil:  proto.Bool(false),
-
-		Stats: encodeIteratorStats(&stats),
-	})
-	if err != nil {
-		return err
-	}
-
-	if err := binary.Write(enc.w, binary.BigEndian, uint32(len(buf))); err != nil {
-		return err
-	}
-	if _, err := enc.w.Write(buf); err != nil {
-		return err
-	}
-	return nil
-}

query/iterator.gen.go.tmpl

@@ -1,9 +1,8 @@
 package query
 
 import (
+	"context"
 	"container/heap"
-	"encoding/binary"
-	"fmt"
 	"io"
 	"sort"
 	"sync"
@@ -11,7 +10,6 @@ import (
 
 	"github.com/gogo/protobuf/proto"
 	"github.com/influxdata/influxdb/influxql"
-	internal "github.com/influxdata/influxdb/query/internal"
 )
 
 // DefaultStatsInterval is the default value for IteratorEncoder.StatsInterval.
@@ -1723,13 +1721,13 @@ type {{$k.name}}ReaderIterator struct {
 }
 
 // new{{$k.Name}}ReaderIterator returns a new instance of {{$k.name}}ReaderIterator.
-func new{{$k.Name}}ReaderIterator(r io.Reader, stats IteratorStats) *{{$k.name}}ReaderIterator {
-	dec := New{{$k.Name}}PointDecoder(r)
+func new{{$k.Name}}ReaderIterator(ctx context.Context, r io.Reader, stats IteratorStats) *{{$k.name}}ReaderIterator {
+	dec := New{{$k.Name}}PointDecoder(ctx, r)
 	dec.stats = stats
 
 	return &{{$k.name}}ReaderIterator{
 		r:     r,
-    dec:   dec,
+		dec:   dec,
 	}
 }
 
@@ -1759,40 +1757,6 @@ func (itr *{{$k.name}}ReaderIterator) Next() (*{{$k.Name}}Point, error) {
 }
 {{end}}
 
-
-// IteratorEncoder is an encoder for encoding an iterator's points to w.
-type IteratorEncoder struct {
-	w io.Writer
-
-	// Frequency with which stats are emitted.
-	StatsInterval time.Duration
-}
-
-// NewIteratorEncoder encodes an iterator's points to w.
-func NewIteratorEncoder(w io.Writer) *IteratorEncoder {
-	return &IteratorEncoder{
-		w: w,
-
-		StatsInterval: DefaultStatsInterval,
-	}
-}
-
-// EncodeIterator encodes and writes all of itr's points to the underlying writer.
-func (enc *IteratorEncoder) EncodeIterator(itr Iterator) error {
-	switch itr := itr.(type) {
-	case FloatIterator:
-		return enc.encodeFloatIterator(itr)
-	case IntegerIterator:
-		return enc.encodeIntegerIterator(itr)
-	case StringIterator:
-		return enc.encodeStringIterator(itr)
-	case BooleanIterator:
-		return enc.encodeBooleanIterator(itr)
-	default:
-		panic(fmt.Sprintf("unsupported iterator for encoder: %T", itr))
-	}
-}
-
 {{range .}}
 // encode{{.Name}}Iterator encodes all points from itr to the underlying writer.
 func (enc *IteratorEncoder) encode{{.Name}}Iterator(itr {{.Name}}Iterator) error {
@@ -1839,27 +1803,4 @@ func (enc *IteratorEncoder) encode{{.Name}}Iterator(itr {{.Name}}Iterator) error
 
 {{end}}
 
-// encode a stats object in the point stream.
-func (enc *IteratorEncoder) encodeStats(stats IteratorStats) error {
-	buf, err := proto.Marshal(&internal.Point{
-		Name: proto.String(""),
-		Tags: proto.String(""),
-		Time: proto.Int64(0),
-		Nil:  proto.Bool(false),
-
-		Stats: encodeIteratorStats(&stats),
-	})
-	if err != nil {
-		return err
-	}
-
-	if err := binary.Write(enc.w, binary.BigEndian, uint32(len(buf))); err != nil {
-		return err
-	}
-	if _, err := enc.w.Write(buf); err != nil {
-		return err
-	}
-	return nil
-}
-
 {{end}}

query/iterator.go

@@ -1,16 +1,18 @@
 package query
 
 import (
+	"context"
+	"encoding/binary"
 	"errors"
 	"fmt"
 	"io"
+	"regexp"
 	"sync"
 	"time"
 
-	"regexp"
-
 	"github.com/gogo/protobuf/proto"
 	"github.com/influxdata/influxdb/influxql"
+	"github.com/influxdata/influxdb/pkg/tracing"
 	internal "github.com/influxdata/influxdb/query/internal"
 )
 
@@ -640,18 +642,18 @@ func DrainIterators(itrs []Iterator) {
 }
 
 // NewReaderIterator returns an iterator that streams from a reader.
-func NewReaderIterator(r io.Reader, typ influxql.DataType, stats IteratorStats) Iterator {
+func NewReaderIterator(ctx context.Context, r io.Reader, typ influxql.DataType, stats IteratorStats) Iterator {
 	switch typ {
 	case influxql.Float:
-		return newFloatReaderIterator(r, stats)
+		return newFloatReaderIterator(ctx, r, stats)
 	case influxql.Integer:
-		return newIntegerReaderIterator(r, stats)
+		return newIntegerReaderIterator(ctx, r, stats)
 	case influxql.Unsigned:
-		return newUnsignedReaderIterator(r, stats)
+		return newUnsignedReaderIterator(ctx, r, stats)
 	case influxql.String:
-		return newStringReaderIterator(r, stats)
+		return newStringReaderIterator(ctx, r, stats)
 	case influxql.Boolean:
-		return newBooleanReaderIterator(r, stats)
+		return newBooleanReaderIterator(ctx, r, stats)
 	default:
 		return &nilFloatReaderIterator{r: r}
 	}
@@ -660,7 +662,7 @@ func NewReaderIterator(r io.Reader, typ influxql.DataType, stats IteratorStats)
 // IteratorCreator is an interface to create Iterators.
 type IteratorCreator interface {
 	// Creates a simple iterator for use in an InfluxQL query.
-	CreateIterator(source *influxql.Measurement, opt IteratorOptions) (Iterator, error)
+	CreateIterator(ctx context.Context, source *influxql.Measurement, opt IteratorOptions) (Iterator, error)
 
 	// Determines the potential cost for creating an iterator.
 	IteratorCost(source *influxql.Measurement, opt IteratorOptions) (IteratorCost, error)
@@ -1426,6 +1428,22 @@ func decodeIteratorStats(pb *internal.IteratorStats) IteratorStats {
 	}
 }
 
+func decodeIteratorTrace(ctx context.Context, data []byte) error {
+	pt := tracing.TraceFromContext(ctx)
+	if pt == nil {
+		return nil
+	}
+
+	var ct tracing.Trace
+	if err := ct.UnmarshalBinary(data); err != nil {
+		return err
+	}
+
+	pt.Merge(&ct)
+
+	return nil
+}
+
 // IteratorCost contains statistics retrieved for explaining what potential
 // cost may be incurred by instantiating an iterator.
 type IteratorCost struct {
@@ -1530,3 +1548,86 @@ func abs(v int64) int64 {
 	}
 	return v
 }
+
+// IteratorEncoder is an encoder for encoding an iterator's points to w.
+type IteratorEncoder struct {
+	w io.Writer
+
+	// Frequency with which stats are emitted.
+	StatsInterval time.Duration
+}
+
+// NewIteratorEncoder encodes an iterator's points to w.
+func NewIteratorEncoder(w io.Writer) *IteratorEncoder {
+	return &IteratorEncoder{
+		w: w,
+
+		StatsInterval: DefaultStatsInterval,
+	}
+}
+
+// EncodeIterator encodes and writes all of itr's points to the underlying writer.
+func (enc *IteratorEncoder) EncodeIterator(itr Iterator) error {
+	switch itr := itr.(type) {
+	case FloatIterator:
+		return enc.encodeFloatIterator(itr)
+	case IntegerIterator:
+		return enc.encodeIntegerIterator(itr)
+	case StringIterator:
+		return enc.encodeStringIterator(itr)
+	case BooleanIterator:
+		return enc.encodeBooleanIterator(itr)
+	default:
+		panic(fmt.Sprintf("unsupported iterator for encoder: %T", itr))
+	}
+}
+
+func (enc *IteratorEncoder) EncodeTrace(trace *tracing.Trace) error {
+	data, err := trace.MarshalBinary()
+	if err != nil {
+		return err
+	}
+
+	buf, err := proto.Marshal(&internal.Point{
+		Name: proto.String(""),
+		Tags: proto.String(""),
+		Time: proto.Int64(0),
+		Nil:  proto.Bool(false),
+
+		Trace: data,
+	})
+	if err != nil {
+		return err
+	}
+
+	if err = binary.Write(enc.w, binary.BigEndian, uint32(len(buf))); err != nil {
+		return err
+	}
+	if _, err = enc.w.Write(buf); err != nil {
+		return err
+	}
+	return nil
+}
+
+// encode a stats object in the point stream.
+func (enc *IteratorEncoder) encodeStats(stats IteratorStats) error {
+	buf, err := proto.Marshal(&internal.Point{
+		Name: proto.String(""),
+		Tags: proto.String(""),
+		Time: proto.Int64(0),
+		Nil:  proto.Bool(false),
+
+		Stats: encodeIteratorStats(&stats),
+	})
+	if err != nil {
+		return err
+	}
+
+	if err = binary.Write(enc.w, binary.BigEndian, uint32(len(buf))); err != nil {
+		return err
+	}
+	if _, err = enc.w.Write(buf); err != nil {
+		return err
+	}
+	return nil
+}

query/iterator_test.go

@@ -2,6 +2,7 @@ package query_test
 
 import (
 	"bytes"
+	"context"
 	"fmt"
 	"math"
 	"reflect"
@@ -1525,7 +1526,7 @@ func TestIterator_EncodeDecode(t *testing.T) {
 	}
 
 	// Decode from the buffer.
-	dec := query.NewReaderIterator(&buf, influxql.Float, itr.Stats())
+	dec := query.NewReaderIterator(context.Background(), &buf, influxql.Float, itr.Stats())
 
 	// Initial stats should exist immediately.
 	fdec := dec.(query.FloatIterator)
@@ -1553,12 +1554,12 @@ func TestIterator_EncodeDecode(t *testing.T) {
 
 // IteratorCreator is a mockable implementation of SelectStatementExecutor.IteratorCreator.
 type IteratorCreator struct {
-	CreateIteratorFn  func(m *influxql.Measurement, opt query.IteratorOptions) (query.Iterator, error)
+	CreateIteratorFn  func(ctx context.Context, m *influxql.Measurement, opt query.IteratorOptions) (query.Iterator, error)
 	FieldDimensionsFn func(m *influxql.Measurement) (fields map[string]influxql.DataType, dimensions map[string]struct{}, err error)
 }
 
-func (ic *IteratorCreator) CreateIterator(m *influxql.Measurement, opt query.IteratorOptions) (query.Iterator, error) {
-	return ic.CreateIteratorFn(m, opt)
+func (ic *IteratorCreator) CreateIterator(ctx context.Context, m *influxql.Measurement, opt query.IteratorOptions) (query.Iterator, error) {
+	return ic.CreateIteratorFn(ctx, m, opt)
 }
 
 func (ic *IteratorCreator) FieldDimensions(m *influxql.Measurement) (fields map[string]influxql.DataType, dimensions map[string]struct{}, err error) {

query/point.gen.go

@@ -7,6 +7,7 @@
 package query
 
 import (
+	"context"
 	"encoding/binary"
 	"io"
 
@@ -181,11 +182,12 @@ func (enc *FloatPointEncoder) EncodeFloatPoint(p *FloatPoint) error {
 type FloatPointDecoder struct {
 	r     io.Reader
 	stats IteratorStats
+	ctx   context.Context
 }
 
 // NewFloatPointDecoder returns a new instance of FloatPointDecoder that reads from r.
-func NewFloatPointDecoder(r io.Reader) *FloatPointDecoder {
-	return &FloatPointDecoder{r: r}
+func NewFloatPointDecoder(ctx context.Context, r io.Reader) *FloatPointDecoder {
+	return &FloatPointDecoder{r: r, ctx: ctx}
 }
 
 // Stats returns iterator stats embedded within the stream.
@@ -218,6 +220,15 @@ func (dec *FloatPointDecoder) DecodeFloatPoint(p *FloatPoint) error {
 			continue
 		}
 
+		if len(pb.Trace) > 0 {
+			var err error
+			err = decodeIteratorTrace(dec.ctx, pb.Trace)
+			if err != nil {
+				return err
+			}
+			continue
+		}
+
 		// Decode into point object.
 		*p = *decodeFloatPoint(&pb)
 
@@ -392,11 +403,12 @@ func (enc *IntegerPointEncoder) EncodeIntegerPoint(p *IntegerPoint) error {
 type IntegerPointDecoder struct {
 	r     io.Reader
 	stats IteratorStats
+	ctx   context.Context
 }
 
 // NewIntegerPointDecoder returns a new instance of IntegerPointDecoder that reads from r.
-func NewIntegerPointDecoder(r io.Reader) *IntegerPointDecoder {
-	return &IntegerPointDecoder{r: r}
+func NewIntegerPointDecoder(ctx context.Context, r io.Reader) *IntegerPointDecoder {
+	return &IntegerPointDecoder{r: r, ctx: ctx}
 }
 
 // Stats returns iterator stats embedded within the stream.
@@ -429,6 +441,15 @@ func (dec *IntegerPointDecoder) DecodeIntegerPoint(p *IntegerPoint) error {
 			continue
 		}
 
+		if len(pb.Trace) > 0 {
+			var err error
+			err = decodeIteratorTrace(dec.ctx, pb.Trace)
+			if err != nil {
+				return err
+			}
+			continue
+		}
+
 		// Decode into point object.
 		*p = *decodeIntegerPoint(&pb)
 
@@ -601,11 +622,12 @@ func (enc *UnsignedPointEncoder) EncodeUnsignedPoint(p *UnsignedPoint) error {
 type UnsignedPointDecoder struct {
 	r     io.Reader
 	stats IteratorStats
+	ctx   context.Context
 }
 
 // NewUnsignedPointDecoder returns a new instance of UnsignedPointDecoder that reads from r.
-func NewUnsignedPointDecoder(r io.Reader) *UnsignedPointDecoder {
-	return &UnsignedPointDecoder{r: r}
+func NewUnsignedPointDecoder(ctx context.Context, r io.Reader) *UnsignedPointDecoder {
+	return &UnsignedPointDecoder{r: r, ctx: ctx}
 }
 
 // Stats returns iterator stats embedded within the stream.
@@ -638,6 +660,15 @@ func (dec *UnsignedPointDecoder) DecodeUnsignedPoint(p *UnsignedPoint) error {
 			continue
 		}
 
+		if len(pb.Trace) > 0 {
+			var err error
+			err = decodeIteratorTrace(dec.ctx, pb.Trace)
+			if err != nil {
+				return err
+			}
+			continue
+		}
+
 		// Decode into point object.
 		*p = *decodeUnsignedPoint(&pb)
 
@@ -812,11 +843,12 @@ func (enc *StringPointEncoder) EncodeStringPoint(p *StringPoint) error {
 type StringPointDecoder struct {
 	r     io.Reader
 	stats IteratorStats
+	ctx   context.Context
 }
 
 // NewStringPointDecoder returns a new instance of StringPointDecoder that reads from r.
-func NewStringPointDecoder(r io.Reader) *StringPointDecoder {
-	return &StringPointDecoder{r: r}
+func NewStringPointDecoder(ctx context.Context, r io.Reader) *StringPointDecoder {
+	return &StringPointDecoder{r: r, ctx: ctx}
 }
 
 // Stats returns iterator stats embedded within the stream.
@@ -849,6 +881,15 @@ func (dec *StringPointDecoder) DecodeStringPoint(p *StringPoint) error {
 			continue
 		}
 
+		if len(pb.Trace) > 0 {
+			var err error
+			err = decodeIteratorTrace(dec.ctx, pb.Trace)
+			if err != nil {
+				return err
+			}
+			continue
+		}
+
 		// Decode into point object.
 		*p = *decodeStringPoint(&pb)
 
@@ -1023,11 +1064,12 @@ func (enc *BooleanPointEncoder) EncodeBooleanPoint(p *BooleanPoint) error {
 type BooleanPointDecoder struct {
 	r     io.Reader
 	stats IteratorStats
+	ctx   context.Context
 }
 
 // NewBooleanPointDecoder returns a new instance of BooleanPointDecoder that reads from r.
-func NewBooleanPointDecoder(r io.Reader) *BooleanPointDecoder {
-	return &BooleanPointDecoder{r: r}
+func NewBooleanPointDecoder(ctx context.Context, r io.Reader) *BooleanPointDecoder {
+	return &BooleanPointDecoder{r: r, ctx: ctx}
 }
 
 // Stats returns iterator stats embedded within the stream.
@@ -1060,6 +1102,15 @@ func (dec *BooleanPointDecoder) DecodeBooleanPoint(p *BooleanPoint) error {
 			continue
 		}
 
+		if len(pb.Trace) > 0 {
+			var err error
+			err = decodeIteratorTrace(dec.ctx, pb.Trace)
+			if err != nil {
+				return err
+			}
+			continue
+		}
+
 		// Decode into point object.
 		*p = *decodeBooleanPoint(&pb)
 

query/point.gen.go.tmpl

@@ -1,6 +1,7 @@
 package query
 
 import (
+	"context"
 	"encoding/binary"
 	"io"
 
@@ -188,11 +189,12 @@ func (enc *{{.Name}}PointEncoder) Encode{{.Name}}Point(p *{{.Name}}Point) error
 type {{.Name}}PointDecoder struct {
 	r     io.Reader
 	stats IteratorStats
+	ctx   context.Context
 }
 
 // New{{.Name}}PointDecoder returns a new instance of {{.Name}}PointDecoder that reads from r.
-func New{{.Name}}PointDecoder(r io.Reader) *{{.Name}}PointDecoder {
-	return &{{.Name}}PointDecoder{r: r}
+func New{{.Name}}PointDecoder(ctx context.Context, r io.Reader) *{{.Name}}PointDecoder {
+	return &{{.Name}}PointDecoder{r: r, ctx: ctx}
 }
 
 // Stats returns iterator stats embedded within the stream.
@@ -225,6 +227,15 @@ func (dec *{{.Name}}PointDecoder) Decode{{.Name}}Point(p *{{.Name}}Point) error
 			continue
 		}
 
+		if len(pb.Trace) > 0 {
+			var err error
+			err = decodeIteratorTrace(dec.ctx, pb.Trace)
+			if err != nil {
+				return err
+			}
+			continue
+		}
+
 		// Decode into point object.
 		*p = *decode{{.Name}}Point(&pb)
 

query/select.go

@@ -1,6 +1,7 @@
 package query
 
 import (
+	"context"
 	"errors"
 	"fmt"
 	"io"
@@ -8,6 +9,7 @@ import (
 	"sort"
 
 	"github.com/influxdata/influxdb/influxql"
+	"github.com/influxdata/influxdb/pkg/tracing"
 )
 
 // SelectOptions are options that customize the select call.
@@ -54,7 +56,7 @@ type ShardGroup interface {
 // Select is a prepared statement that is ready to be executed.
 type PreparedStatement interface {
 	// Select creates the Iterators that will be used to read the query.
-	Select() ([]Iterator, []string, error)
+	Select(ctx context.Context) ([]Iterator, []string, error)
 
 	// Explain outputs the explain plan for this statement.
 	Explain() (string, error)
@@ -77,14 +79,14 @@ func Prepare(stmt *influxql.SelectStatement, shardMapper ShardMapper, opt Select
 
 // Select compiles, prepares, and then initiates execution of the query using the
 // default compile options.
-func Select(stmt *influxql.SelectStatement, shardMapper ShardMapper, opt SelectOptions) ([]Iterator, []string, error) {
+func Select(ctx context.Context, stmt *influxql.SelectStatement, shardMapper ShardMapper, opt SelectOptions) ([]Iterator, []string, error) {
 	s, err := Prepare(stmt, shardMapper, opt)
 	if err != nil {
 		return nil, nil, err
 	}
 	// Must be deferred so it runs after Select.
 	defer s.Close()
-	return s.Select()
+	return s.Select(ctx)
 }
 
 type preparedStatement struct {
@@ -97,8 +99,8 @@ type preparedStatement struct {
 	columns []string
 }
 
-func (p *preparedStatement) Select() ([]Iterator, []string, error) {
-	itrs, err := buildIterators(p.stmt, p.ic, p.opt)
+func (p *preparedStatement) Select(ctx context.Context) ([]Iterator, []string, error) {
+	itrs, err := buildIterators(ctx, p.stmt, p.ic, p.opt)
 	if err != nil {
 		return nil, nil, err
 	}
@@ -109,7 +111,8 @@ func (p *preparedStatement) Close() error {
 	return p.ic.Close()
 }
 
-func buildIterators(stmt *influxql.SelectStatement, ic IteratorCreator, opt IteratorOptions) ([]Iterator, error) {
+func buildIterators(ctx context.Context, stmt *influxql.SelectStatement, ic IteratorCreator, opt IteratorOptions) ([]Iterator, error) {
+	span := tracing.SpanFromContext(ctx)
 	// Retrieve refs for each call and var ref.
 	info := newSelectInfo(stmt)
 	if len(info.calls) > 1 && len(info.refs) > 0 {
@@ -125,7 +128,22 @@ func buildIterators(stmt *influxql.SelectStatement, ic IteratorCreator, opt Iter
 
 	// If there are multiple auxilary fields and no calls then construct an aux iterator.
 	if len(info.calls) == 0 && len(info.refs) > 0 {
-		return buildAuxIterators(stmt.Fields, ic, stmt.Sources, opt)
+		if span != nil {
+			span = span.StartSpan("auxiliary_iterators")
+			defer span.Finish()
+
+			span.SetLabels("statement", stmt.String())
+			ctx = tracing.NewContextWithSpan(ctx, span)
+		}
+		return buildAuxIterators(ctx, stmt.Fields, ic, stmt.Sources, opt)
+	}
+
+	if span != nil {
+		span = span.StartSpan("field_iterators")
+		defer span.Finish()
+
+		span.SetLabels("statement", stmt.String())
+		ctx = tracing.NewContextWithSpan(ctx, span)
 	}
 
 	// Include auxiliary fields from top() and bottom() when not writing the results.
@@ -167,18 +185,18 @@ func buildIterators(stmt *influxql.SelectStatement, ic IteratorCreator, opt Iter
 		}
 	}
 
-	return buildFieldIterators(fields, ic, stmt.Sources, opt, selector, stmt.Target != nil)
+	return buildFieldIterators(ctx, fields, ic, stmt.Sources, opt, selector, stmt.Target != nil)
 }
 
 // buildAuxIterators creates a set of iterators from a single combined auxiliary iterator.
-func buildAuxIterators(fields influxql.Fields, ic IteratorCreator, sources influxql.Sources, opt IteratorOptions) ([]Iterator, error) {
+func buildAuxIterators(ctx context.Context, fields influxql.Fields, ic IteratorCreator, sources influxql.Sources, opt IteratorOptions) ([]Iterator, error) {
 	// Create the auxiliary iterators for each source.
 	inputs := make([]Iterator, 0, len(sources))
 	if err := func() error {
 		for _, source := range sources {
 			switch source := source.(type) {
 			case *influxql.Measurement:
-				input, err := ic.CreateIterator(source, opt)
+				input, err := ic.CreateIterator(ctx, source, opt)
 				if err != nil {
 					return err
 				}
@@ -189,7 +207,7 @@ func buildAuxIterators(fields influxql.Fields, ic IteratorCreator, sources influ
 					stmt: source.Statement,
 				}
 
-				input, err := b.buildAuxIterator(opt)
+				input, err := b.buildAuxIterator(ctx, opt)
 				if err != nil {
 					return err
 				}
@@ -304,9 +322,10 @@ func buildAuxIterator(expr influxql.Expr, aitr AuxIterator, opt IteratorOptions)
 }
 
 // buildFieldIterators creates an iterator for each field expression.
-func buildFieldIterators(fields influxql.Fields, ic IteratorCreator, sources influxql.Sources, opt IteratorOptions, selector, writeMode bool) ([]Iterator, error) {
+func buildFieldIterators(ctx context.Context, fields influxql.Fields, ic IteratorCreator, sources influxql.Sources, opt IteratorOptions, selector, writeMode bool) ([]Iterator, error) {
 	// Create iterators from fields against the iterator creator.
 	itrs := make([]Iterator, len(fields))
+	span := tracing.SpanFromContext(ctx)
 
 	if err := func() error {
 		hasAuxFields := false
@@ -321,8 +340,22 @@ func buildFieldIterators(fields influxql.Fields, ic IteratorCreator, sources inf
 				continue
 			}
 
+			var localSpan *tracing.Span
+			localContext := ctx
+
+			if span != nil {
+				localSpan = span.StartSpan("expression")
+				localSpan.SetLabels("expr", f.Expr.String())
+				localContext = tracing.NewContextWithSpan(ctx, localSpan)
+			}
+
 			expr := influxql.Reduce(f.Expr, nil)
-			itr, err := buildExprIterator(expr, ic, sources, opt, selector, writeMode)
+			itr, err := buildExprIterator(localContext, expr, ic, sources, opt, selector, writeMode)
+
+			if localSpan != nil {
+				localSpan.Finish()
+			}
+
 			if err != nil {
 				return err
 			} else if itr == nil {
@@ -371,7 +404,7 @@ func buildFieldIterators(fields influxql.Fields, ic IteratorCreator, sources inf
 }
 
 // buildExprIterator creates an iterator for an expression.
-func buildExprIterator(expr influxql.Expr, ic IteratorCreator, sources influxql.Sources, opt IteratorOptions, selector, writeMode bool) (Iterator, error) {
+func buildExprIterator(ctx context.Context, expr influxql.Expr, ic IteratorCreator, sources influxql.Sources, opt IteratorOptions, selector, writeMode bool) (Iterator, error) {
 	opt.Expr = expr
 	b := exprIteratorBuilder{
 		ic:        ic,
@@ -383,13 +416,13 @@ func buildExprIterator(expr influxql.Expr, ic IteratorCreator, sources influxql.
 
 	switch expr := expr.(type) {
 	case *influxql.VarRef:
-		return b.buildVarRefIterator(expr)
+		return b.buildVarRefIterator(ctx, expr)
 	case *influxql.Call:
-		return b.buildCallIterator(expr)
+		return b.buildCallIterator(ctx, expr)
 	case *influxql.BinaryExpr:
-		return b.buildBinaryExprIterator(expr)
+		return b.buildBinaryExprIterator(ctx, expr)
 	case *influxql.ParenExpr:
-		return buildExprIterator(expr.Expr, ic, sources, opt, selector, writeMode)
+		return buildExprIterator(ctx, expr.Expr, ic, sources, opt, selector, writeMode)
 	case *influxql.NilLiteral:
 		return &nilFloatIterator{}, nil
 	default:
@@ -405,13 +438,13 @@ type exprIteratorBuilder struct {
 	writeMode bool
 }
 
-func (b *exprIteratorBuilder) buildVarRefIterator(expr *influxql.VarRef) (Iterator, error) {
+func (b *exprIteratorBuilder) buildVarRefIterator(ctx context.Context, expr *influxql.VarRef) (Iterator, error) {
 	inputs := make([]Iterator, 0, len(b.sources))
 	if err := func() error {
 		for _, source := range b.sources {
 			switch source := source.(type) {
 			case *influxql.Measurement:
-				input, err := b.ic.CreateIterator(source, b.opt)
+				input, err := b.ic.CreateIterator(ctx, source, b.opt)
 				if err != nil {
 					return err
 				}
@@ -422,7 +455,7 @@ func (b *exprIteratorBuilder) buildVarRefIterator(expr *influxql.VarRef) (Iterat
 					stmt: source.Statement,
 				}
 
-				input, err := subquery.buildVarRefIterator(expr, b.opt)
+				input, err := subquery.buildVarRefIterator(ctx, expr, b.opt)
 				if err != nil {
 					return err
 				}
@@ -448,7 +481,7 @@ func (b *exprIteratorBuilder) buildVarRefIterator(expr *influxql.VarRef) (Iterat
 	return itr, nil
 }
 
-func (b *exprIteratorBuilder) buildCallIterator(expr *influxql.Call) (Iterator, error) {
+func (b *exprIteratorBuilder) buildCallIterator(ctx context.Context, expr *influxql.Call) (Iterator, error) {
 	// TODO(jsternberg): Refactor this. This section needs to die in a fire.
 	opt := b.opt
 	// Eliminate limits and offsets if they were previously set. These are handled by the caller.
@@ -456,7 +489,7 @@ func (b *exprIteratorBuilder) buildCallIterator(expr *influxql.Call) (Iterator,
 	switch expr.Name {
 	case "distinct":
 		opt.Ordered = true
-		input, err := buildExprIterator(expr.Args[0].(*influxql.VarRef), b.ic, b.sources, opt, b.selector, false)
+		input, err := buildExprIterator(ctx, expr.Args[0].(*influxql.VarRef), b.ic, b.sources, opt, b.selector, false)
 		if err != nil {
 			return nil, err
 		}
@@ -467,7 +500,7 @@ func (b *exprIteratorBuilder) buildCallIterator(expr *influxql.Call) (Iterator,
 		return NewIntervalIterator(input, opt), nil
 	case "sample":
 		opt.Ordered = true
-		input, err := buildExprIterator(expr.Args[0], b.ic, b.sources, opt, b.selector, false)
+		input, err := buildExprIterator(ctx, expr.Args[0], b.ic, b.sources, opt, b.selector, false)
 		if err != nil {
 			return nil, err
 		}
@@ -476,7 +509,7 @@ func (b *exprIteratorBuilder) buildCallIterator(expr *influxql.Call) (Iterator,
 		return newSampleIterator(input, opt, int(size.Val))
 	case "holt_winters", "holt_winters_with_fit":
 		opt.Ordered = true
-		input, err := buildExprIterator(expr.Args[0], b.ic, b.sources, opt, b.selector, false)
+		input, err := buildExprIterator(ctx, expr.Args[0], b.ic, b.sources, opt, b.selector, false)
 		if err != nil {
 			return nil, err
 		}
@@ -502,7 +535,7 @@ func (b *exprIteratorBuilder) buildCallIterator(expr *influxql.Call) (Iterator,
 		}
 		opt.Ordered = true
 
-		input, err := buildExprIterator(expr.Args[0], b.ic, b.sources, opt, b.selector, false)
+		input, err := buildExprIterator(ctx, expr.Args[0], b.ic, b.sources, opt, b.selector, false)
 		if err != nil {
 			return nil, err
 		}
@@ -532,14 +565,14 @@ func (b *exprIteratorBuilder) buildCallIterator(expr *influxql.Call) (Iterator,
 		panic(fmt.Sprintf("invalid series aggregate function: %s", expr.Name))
 	case "cumulative_sum":
 		opt.Ordered = true
-		input, err := buildExprIterator(expr.Args[0], b.ic, b.sources, opt, b.selector, false)
+		input, err := buildExprIterator(ctx, expr.Args[0], b.ic, b.sources, opt, b.selector, false)
 		if err != nil {
 			return nil, err
 		}
 		return newCumulativeSumIterator(input, opt)
 	case "integral":
 		opt.Ordered = true
-		input, err := buildExprIterator(expr.Args[0].(*influxql.VarRef), b.ic, b.sources, opt, false, false)
+		input, err := buildExprIterator(ctx, expr.Args[0].(*influxql.VarRef), b.ic, b.sources, opt, false, false)
 		if err != nil {
 			return nil, err
 		}
@@ -576,7 +609,7 @@ func (b *exprIteratorBuilder) buildCallIterator(expr *influxql.Call) (Iterator,
 			builder.selector = true
 			builder.writeMode = false
 
-			i, err := builder.callIterator(call, callOpt)
+			i, err := builder.callIterator(ctx, call, callOpt)
 			if err != nil {
 				return nil, err
 			}
@@ -589,7 +622,7 @@ func (b *exprIteratorBuilder) buildCallIterator(expr *influxql.Call) (Iterator,
 			builder.writeMode = false
 
 			ref := expr.Args[0].(*influxql.VarRef)
-			i, err := builder.buildVarRefIterator(ref)
+			i, err := builder.buildVarRefIterator(ctx, ref)
 			if err != nil {
 				return nil, err
 			}
@@ -629,7 +662,7 @@ func (b *exprIteratorBuilder) buildCallIterator(expr *influxql.Call) (Iterator,
 			builder.selector = true
 			builder.writeMode = false
 
-			i, err := builder.callIterator(call, callOpt)
+			i, err := builder.callIterator(ctx, call, callOpt)
 			if err != nil {
 				return nil, err
 			}
@@ -642,7 +675,7 @@ func (b *exprIteratorBuilder) buildCallIterator(expr *influxql.Call) (Iterator,
 			builder.writeMode = false
 
 			ref := expr.Args[0].(*influxql.VarRef)
-			i, err := builder.buildVarRefIterator(ref)
+			i, err := builder.buildVarRefIterator(ctx, ref)
 			if err != nil {
 				return nil, err
 			}
@@ -659,7 +692,7 @@ func (b *exprIteratorBuilder) buildCallIterator(expr *influxql.Call) (Iterator,
 			switch arg0 := expr.Args[0].(type) {
 			case *influxql.Call:
 				if arg0.Name == "distinct" {
-					input, err := buildExprIterator(arg0, b.ic, b.sources, opt, b.selector, false)
+					input, err := buildExprIterator(ctx, arg0, b.ic, b.sources, opt, b.selector, false)
 					if err != nil {
 						return nil, err
 					}
@@ -668,36 +701,36 @@ func (b *exprIteratorBuilder) buildCallIterator(expr *influxql.Call) (Iterator,
 			}
 			fallthrough
 		case "min", "max", "sum", "first", "last", "mean":
-			return b.callIterator(expr, opt)
+			return b.callIterator(ctx, expr, opt)
 		case "median":
 			opt.Ordered = true
-			input, err := buildExprIterator(expr.Args[0].(*influxql.VarRef), b.ic, b.sources, opt, false, false)
+			input, err := buildExprIterator(ctx, expr.Args[0].(*influxql.VarRef), b.ic, b.sources, opt, false, false)
 			if err != nil {
 				return nil, err
 			}
 			return newMedianIterator(input, opt)
 		case "mode":
-			input, err := buildExprIterator(expr.Args[0].(*influxql.VarRef), b.ic, b.sources, opt, false, false)
+			input, err := buildExprIterator(ctx, expr.Args[0].(*influxql.VarRef), b.ic, b.sources, opt, false, false)
 			if err != nil {
 				return nil, err
 			}
 			return NewModeIterator(input, opt)
 		case "stddev":
-			input, err := buildExprIterator(expr.Args[0].(*influxql.VarRef), b.ic, b.sources, opt, false, false)
+			input, err := buildExprIterator(ctx, expr.Args[0].(*influxql.VarRef), b.ic, b.sources, opt, false, false)
 			if err != nil {
 				return nil, err
 			}
 			return newStddevIterator(input, opt)
 		case "spread":
 			// OPTIMIZE(benbjohnson): convert to map/reduce
-			input, err := buildExprIterator(expr.Args[0].(*influxql.VarRef), b.ic, b.sources, opt, false, false)
+			input, err := buildExprIterator(ctx, expr.Args[0].(*influxql.VarRef), b.ic, b.sources, opt, false, false)
 			if err != nil {
 				return nil, err
 			}
 			return newSpreadIterator(input, opt)
 		case "percentile":
 			opt.Ordered = true
-			input, err := buildExprIterator(expr.Args[0].(*influxql.VarRef), b.ic, b.sources, opt, false, false)
+			input, err := buildExprIterator(ctx, expr.Args[0].(*influxql.VarRef), b.ic, b.sources, opt, false, false)
 			if err != nil {
 				return nil, err
 			}
@@ -730,7 +763,7 @@ func (b *exprIteratorBuilder) buildCallIterator(expr *influxql.Call) (Iterator,
 	return itr, nil
 }
 
-func (b *exprIteratorBuilder) buildBinaryExprIterator(expr *influxql.BinaryExpr) (Iterator, error) {
+func (b *exprIteratorBuilder) buildBinaryExprIterator(ctx context.Context, expr *influxql.BinaryExpr) (Iterator, error) {
 	if rhs, ok := expr.RHS.(influxql.Literal); ok {
 		// The right hand side is a literal. It is more common to have the RHS be a literal,
 		// so we check that one first and have this be the happy path.
@@ -739,24 +772,24 @@ func (b *exprIteratorBuilder) buildBinaryExprIterator(expr *influxql.BinaryExpr)
 			return nil, fmt.Errorf("unable to construct an iterator from two literals: LHS: %T, RHS: %T", lhs, rhs)
 		}
 
-		lhs, err := buildExprIterator(expr.LHS, b.ic, b.sources, b.opt, b.selector, false)
+		lhs, err := buildExprIterator(ctx, expr.LHS, b.ic, b.sources, b.opt, b.selector, false)
 		if err != nil {
 			return nil, err
 		}
 		return buildRHSTransformIterator(lhs, rhs, expr.Op, b.opt)
 	} else if lhs, ok := expr.LHS.(influxql.Literal); ok {
-		rhs, err := buildExprIterator(expr.RHS, b.ic, b.sources, b.opt, b.selector, false)
+		rhs, err := buildExprIterator(ctx, expr.RHS, b.ic, b.sources, b.opt, b.selector, false)
 		if err != nil {
 			return nil, err
 		}
 		return buildLHSTransformIterator(lhs, rhs, expr.Op, b.opt)
 	} else {
 		// We have two iterators. Combine them into a single iterator.
-		lhs, err := buildExprIterator(expr.LHS, b.ic, b.sources, b.opt, false, false)
+		lhs, err := buildExprIterator(ctx, expr.LHS, b.ic, b.sources, b.opt, false, false)
 		if err != nil {
 			return nil, err
 		}
-		rhs, err := buildExprIterator(expr.RHS, b.ic, b.sources, b.opt, false, false)
+		rhs, err := buildExprIterator(ctx, expr.RHS, b.ic, b.sources, b.opt, false, false)
 		if err != nil {
 			return nil, err
 		}
@@ -764,13 +797,13 @@ func (b *exprIteratorBuilder) buildBinaryExprIterator(expr *influxql.BinaryExpr)
 	}
 }
 
-func (b *exprIteratorBuilder) callIterator(expr *influxql.Call, opt IteratorOptions) (Iterator, error) {
+func (b *exprIteratorBuilder) callIterator(ctx context.Context, expr *influxql.Call, opt IteratorOptions) (Iterator, error) {
 	inputs := make([]Iterator, 0, len(b.sources))
 	if err := func() error {
 		for _, source := range b.sources {
 			switch source := source.(type) {
 			case *influxql.Measurement:
-				input, err := b.ic.CreateIterator(source, opt)
+				input, err := b.ic.CreateIterator(ctx, source, opt)
 				if err != nil {
 					return err
 				}
@@ -779,7 +812,7 @@ func (b *exprIteratorBuilder) callIterator(expr *influxql.Call, opt IteratorOpti
 				// Identify the name of the field we are using.
 				arg0 := expr.Args[0].(*influxql.VarRef)
 
-				input, err := buildExprIterator(arg0, b.ic, []influxql.Source{source}, opt, b.selector, false)
+				input, err := buildExprIterator(ctx, arg0, b.ic, []influxql.Source{source}, opt, b.selector, false)
 				if err != nil {
 					return err
 				}

query/select_test.go

@@ -1,6 +1,7 @@
 package query_test
 
 import (
+	"context"
 	"fmt"
 	"math/rand"
 	"reflect"
@@ -2765,7 +2766,7 @@ func TestSelect(t *testing.T) {
 							"value": tt.typ,
 						},
 						Dimensions: []string{"host", "region"},
-						CreateIteratorFn: func(m *influxql.Measurement, opt query.IteratorOptions) (query.Iterator, error) {
+						CreateIteratorFn: func(ctx context.Context, m *influxql.Measurement, opt query.IteratorOptions) (query.Iterator, error) {
 							if m.Name != "cpu" {
 								t.Fatalf("unexpected source: %s", m.Name)
 							}
@@ -2789,7 +2790,7 @@ func TestSelect(t *testing.T) {
 				},
 			}
 
-			itrs, _, err := query.Select(MustParseSelectStatement(tt.q), &shardMapper, query.SelectOptions{})
+			itrs, _, err := query.Select(context.Background(), MustParseSelectStatement(tt.q), &shardMapper, query.SelectOptions{})
 			if err != nil {
 				if tt.err == "" {
 					t.Fatal(err)
@@ -2819,7 +2820,7 @@ func TestSelect_Raw(t *testing.T) {
 					"s": influxql.String,
 					"b": influxql.Boolean,
 				},
-				CreateIteratorFn: func(m *influxql.Measurement, opt query.IteratorOptions) (query.Iterator, error) {
+				CreateIteratorFn: func(ctx context.Context, m *influxql.Measurement, opt query.IteratorOptions) (query.Iterator, error) {
 					if m.Name != "cpu" {
 						t.Fatalf("unexpected source: %s", m.Name)
 					}
@@ -2846,7 +2847,7 @@ func TestSelect_Raw(t *testing.T) {
 	}
 
 	stmt := MustParseSelectStatement(`SELECT f, i, u, s, b FROM cpu`)
-	itrs, _, err := query.Select(stmt, &shardMapper, query.SelectOptions{})
+	itrs, _, err := query.Select(context.Background(), stmt, &shardMapper, query.SelectOptions{})
 	if err != nil {
 		t.Errorf("parse error: %s", err)
 	} else if a, err := Iterators(itrs).ReadAll(); err != nil {
@@ -2888,7 +2889,7 @@ func TestSelect_BinaryExpr(t *testing.T) {
 					"i": influxql.Integer,
 					"u": influxql.Unsigned,
 				},
-				CreateIteratorFn: func(m *influxql.Measurement, opt query.IteratorOptions) (query.Iterator, error) {
+				CreateIteratorFn: func(ctx context.Context, m *influxql.Measurement, opt query.IteratorOptions) (query.Iterator, error) {
 					if m.Name != "cpu" {
 						t.Fatalf("unexpected source: %s", m.Name)
 					}
@@ -3753,7 +3754,7 @@ func TestSelect_BinaryExpr(t *testing.T) {
 	} {
 		t.Run(test.Name, func(t *testing.T) {
 			stmt := MustParseSelectStatement(test.Statement)
-			itrs, _, err := query.Select(stmt, &shardMapper, query.SelectOptions{})
+			itrs, _, err := query.Select(context.Background(), stmt, &shardMapper, query.SelectOptions{})
 			if err != nil {
 				if have, want := err.Error(), test.Err; want != "" {
 					if have != want {
@@ -3782,7 +3783,7 @@ func TestSelect_BinaryExpr_Boolean(t *testing.T) {
 					"one": influxql.Boolean,
 					"two": influxql.Boolean,
 				},
-				CreateIteratorFn: func(m *influxql.Measurement, opt query.IteratorOptions) (query.Iterator, error) {
+				CreateIteratorFn: func(ctx context.Context, m *influxql.Measurement, opt query.IteratorOptions) (query.Iterator, error) {
 					if m.Name != "cpu" {
 						t.Fatalf("unexpected source: %s", m.Name)
 					}
@@ -3838,7 +3839,7 @@ func TestSelect_BinaryExpr_Boolean(t *testing.T) {
 	} {
 		t.Run(test.Name, func(t *testing.T) {
 			stmt := MustParseSelectStatement(test.Statement)
-			itrs, _, err := query.Select(stmt, &shardMapper, query.SelectOptions{})
+			itrs, _, err := query.Select(context.Background(), stmt, &shardMapper, query.SelectOptions{})
 			if err != nil {
 				t.Errorf("%s: parse error: %s", test.Name, err)
 			} else if a, err := Iterators(itrs).ReadAll(); err != nil {
@@ -3861,7 +3862,7 @@ func TestSelect_BinaryExpr_NilValues(t *testing.T) {
 					"total": influxql.Float,
 					"value": influxql.Float,
 				},
-				CreateIteratorFn: func(m *influxql.Measurement, opt query.IteratorOptions) (query.Iterator, error) {
+				CreateIteratorFn: func(ctx context.Context, m *influxql.Measurement, opt query.IteratorOptions) (query.Iterator, error) {
 					if m.Name != "cpu" {
 						t.Fatalf("unexpected source: %s", m.Name)
 					}
@@ -3919,7 +3920,7 @@ func TestSelect_BinaryExpr_NilValues(t *testing.T) {
 	} {
 		t.Run(test.Name, func(t *testing.T) {
 			stmt := MustParseSelectStatement(test.Statement)
-			itrs, _, err := query.Select(stmt, &shardMapper, query.SelectOptions{})
+			itrs, _, err := query.Select(context.Background(), stmt, &shardMapper, query.SelectOptions{})
 			if err != nil {
 				t.Errorf("%s: parse error: %s", test.Name, err)
 			} else if a, err := Iterators(itrs).ReadAll(); err != nil {
@@ -3941,13 +3942,13 @@ func (m *ShardMapper) MapShards(sources influxql.Sources, t influxql.TimeRange,
 }
 
 type ShardGroup struct {
-	CreateIteratorFn func(m *influxql.Measurement, opt query.IteratorOptions) (query.Iterator, error)
+	CreateIteratorFn func(ctx context.Context, m *influxql.Measurement, opt query.IteratorOptions) (query.Iterator, error)
 	Fields           map[string]influxql.DataType
 	Dimensions       []string
 }
 
-func (sh *ShardGroup) CreateIterator(m *influxql.Measurement, opt query.IteratorOptions) (query.Iterator, error) {
-	return sh.CreateIteratorFn(m, opt)
+func (sh *ShardGroup) CreateIterator(ctx context.Context, m *influxql.Measurement, opt query.IteratorOptions) (query.Iterator, error) {
+	return sh.CreateIteratorFn(ctx, m, opt)
 }
 
 func (sh *ShardGroup) IteratorCost(m *influxql.Measurement, opt query.IteratorOptions) (query.IteratorCost, error) {
@@ -3994,7 +3995,7 @@ func benchmarkSelect(b *testing.B, stmt *influxql.SelectStatement, shardMapper q
 	b.ReportAllocs()
 
 	for i := 0; i < b.N; i++ {
-		itrs, _, err := query.Select(stmt, shardMapper, query.SelectOptions{})
+		itrs, _, err := query.Select(context.Background(), stmt, shardMapper, query.SelectOptions{})
 		if err != nil {
 			b.Fatal(err)
 		}
@@ -4010,7 +4011,7 @@ func NewRawBenchmarkIteratorCreator(pointN int) query.ShardMapper {
 				Fields: map[string]influxql.DataType{
 					"fval": influxql.Float,
 				},
-				CreateIteratorFn: func(m *influxql.Measurement, opt query.IteratorOptions) (query.Iterator, error) {
+				CreateIteratorFn: func(ctx context.Context, m *influxql.Measurement, opt query.IteratorOptions) (query.Iterator, error) {
 					if opt.Expr != nil {
 						panic("unexpected expression")
 					}
@@ -4049,7 +4050,7 @@ func benchmarkSelectDedupe(b *testing.B, seriesN, pointsPerSeries int) {
 				Fields: map[string]influxql.DataType{
 					"sval": influxql.String,
 				},
-				CreateIteratorFn: func(m *influxql.Measurement, opt query.IteratorOptions) (query.Iterator, error) {
+				CreateIteratorFn: func(ctx context.Context, m *influxql.Measurement, opt query.IteratorOptions) (query.Iterator, error) {
 					if opt.Expr != nil {
 						panic("unexpected expression")
 					}
@@ -4083,7 +4084,7 @@ func benchmarkSelectTop(b *testing.B, seriesN, pointsPerSeries int) {
 				Fields: map[string]influxql.DataType{
 					"sval": influxql.Float,
 				},
-				CreateIteratorFn: func(m *influxql.Measurement, opt query.IteratorOptions) (query.Iterator, error) {
+				CreateIteratorFn: func(ctx context.Context, m *influxql.Measurement, opt query.IteratorOptions) (query.Iterator, error) {
 					if m.Name != "cpu" {
 						b.Fatalf("unexpected source: %s", m.Name)
 					}

query/subquery.go

@@ -1,6 +1,10 @@
 package query
 
-import "github.com/influxdata/influxdb/influxql"
+import (
+	"context"
+
+	"github.com/influxdata/influxdb/influxql"
+)
 
 type subqueryBuilder struct {
 	ic   IteratorCreator
@@ -8,7 +12,7 @@ type subqueryBuilder struct {
 }
 
 // buildAuxIterator constructs an auxiliary Iterator from a subquery.
-func (b *subqueryBuilder) buildAuxIterator(opt IteratorOptions) (Iterator, error) {
+func (b *subqueryBuilder) buildAuxIterator(ctx context.Context, opt IteratorOptions) (Iterator, error) {
 	// Retrieve a list of fields needed for conditions.
 	auxFields := opt.Aux
 	conds := influxql.ExprNames(opt.Condition)
@@ -26,7 +30,7 @@ func (b *subqueryBuilder) buildAuxIterator(opt IteratorOptions) (Iterator, error
 	}
 	subOpt.Aux = auxFields
 
-	itrs, err := buildIterators(b.stmt, b.ic, subOpt)
+	itrs, err := buildIterators(ctx, b.stmt, b.ic, subOpt)
 	if err != nil {
 		return nil, err
 	}
@@ -85,7 +89,7 @@ func (b *subqueryBuilder) mapAuxField(name *influxql.VarRef) IteratorMap {
 	return nil
 }
 
-func (b *subqueryBuilder) buildVarRefIterator(expr *influxql.VarRef, opt IteratorOptions) (Iterator, error) {
+func (b *subqueryBuilder) buildVarRefIterator(ctx context.Context, expr *influxql.VarRef, opt IteratorOptions) (Iterator, error) {
 	// Look for the field or tag that is driving this query.
 	driver := b.mapAuxField(expr)
 	if driver == nil {
@@ -116,7 +120,7 @@ func (b *subqueryBuilder) buildVarRefIterator(expr *influxql.VarRef, opt Iterato
 	}
 	subOpt.Aux = auxFields
 
-	itrs, err := buildIterators(b.stmt, b.ic, subOpt)
+	itrs, err := buildIterators(ctx, b.stmt, b.ic, subOpt)
 	if err != nil {
 		return nil, err
 	}

tsdb/engine.go

@@ -1,6 +1,7 @@
 package tsdb
 
 import (
+	"context"
 	"errors"
 	"fmt"
 	"io"
@@ -43,7 +44,7 @@ type Engine interface {
 	Restore(r io.Reader, basePath string) error
 	Import(r io.Reader, basePath string) error
 
-	CreateIterator(measurement string, opt query.IteratorOptions) (query.Iterator, error)
+	CreateIterator(ctx context.Context, measurement string, opt query.IteratorOptions) (query.Iterator, error)
 	IteratorCost(measurement string, opt query.IteratorOptions) (query.IteratorCost, error)
 	WritePoints(points []models.Point) error
 

tsdb/engine/tsm1/engine.go

@@ -4,6 +4,7 @@ package tsm1 // import "github.com/influxdata/influxdb/tsdb/engine/tsm1"
 import (
 	"archive/tar"
 	"bytes"
+	"context"
 	"fmt"
 	"io"
 	"io/ioutil"
@@ -12,6 +13,7 @@ import (
 	"path/filepath"
 	"regexp"
 	"runtime"
+	"strconv"
 	"strings"
 	"sync"
 	"sync/atomic"
@@ -22,6 +24,8 @@ import (
 	"github.com/influxdata/influxdb/pkg/bytesutil"
 	"github.com/influxdata/influxdb/pkg/estimator"
 	"github.com/influxdata/influxdb/pkg/limiter"
+	"github.com/influxdata/influxdb/pkg/metrics"
+	"github.com/influxdata/influxdb/pkg/tracing"
 	"github.com/influxdata/influxdb/query"
 	"github.com/influxdata/influxdb/tsdb"
 	_ "github.com/influxdata/influxdb/tsdb/index"
@@ -47,6 +51,14 @@ var (
 	keyFieldSeparatorBytes = []byte(keyFieldSeparator)
 )
 
+var (
+	tsmGroup                   = metrics.MustRegisterGroup("tsm1")
+	numberOfRefCursorsCounter  = metrics.MustRegisterCounter("cursors_ref", metrics.WithGroup(tsmGroup))
+	numberOfAuxCursorsCounter  = metrics.MustRegisterCounter("cursors_aux", metrics.WithGroup(tsmGroup))
+	numberOfCondCursorsCounter = metrics.MustRegisterCounter("cursors_cond", metrics.WithGroup(tsmGroup))
+	planningTimer              = metrics.MustRegisterTimer("planning_time", metrics.WithGroup(tsmGroup))
+)
+
 const (
 	// keyFieldSeparator separates the series key from the field name in the composite key
 	// that identifies a specific field in series
@@ -1670,12 +1682,29 @@ func (e *Engine) cleanupTempTSMFiles() error {
 }
 
 // KeyCursor returns a KeyCursor for the given key starting at time t.
-func (e *Engine) KeyCursor(key []byte, t int64, ascending bool) *KeyCursor {
-	return e.FileStore.KeyCursor(key, t, ascending)
+func (e *Engine) KeyCursor(ctx context.Context, key []byte, t int64, ascending bool) *KeyCursor {
+	return e.FileStore.KeyCursor(ctx, key, t, ascending)
 }
 
 // CreateIterator returns an iterator for the measurement based on opt.
-func (e *Engine) CreateIterator(measurement string, opt query.IteratorOptions) (query.Iterator, error) {
+func (e *Engine) CreateIterator(ctx context.Context, measurement string, opt query.IteratorOptions) (query.Iterator, error) {
+	if span := tracing.SpanFromContext(ctx); span != nil {
+		labels := []string{"shard_id", strconv.Itoa(int(e.id)), "measurement", measurement}
+		if opt.Condition != nil {
+			labels = append(labels, "cond", opt.Condition.String())
+		}
+
+		span = span.StartSpan("create_iterator")
+		span.SetLabels(labels...)
+		ctx = tracing.NewContextWithSpan(ctx, span)
+
+		group := metrics.NewGroup(tsmGroup)
+		ctx = metrics.NewContextWithGroup(ctx, group)
+		start := time.Now()
+
+		defer group.GetTimer(planningTimer).UpdateSince(start)
+	}
+
 	if call, ok := opt.Expr.(*influxql.Call); ok {
 		if opt.Interval.IsZero() {
 			if call.Name == "first" || call.Name == "last" {
@@ -1685,31 +1714,31 @@ func (e *Engine) CreateIterator(measurement string, opt query.IteratorOptions) (
 				refOpt.Ordered = true
 				refOpt.Expr = call.Args[0]
 
-				itrs, err := e.createVarRefIterator(measurement, refOpt)
+				itrs, err := e.createVarRefIterator(ctx, measurement, refOpt)
 				if err != nil {
 					return nil, err
 				}
-				return newMergeFinalizerIterator(itrs, opt, e.logger)
+				return newMergeFinalizerIterator(ctx, itrs, opt, e.logger)
 			}
 		}
 
-		inputs, err := e.createCallIterator(measurement, call, opt)
+		inputs, err := e.createCallIterator(ctx, measurement, call, opt)
 		if err != nil {
 			return nil, err
 		} else if len(inputs) == 0 {
 			return nil, nil
 		}
-		return newMergeFinalizerIterator(inputs, opt, e.logger)
+		return newMergeFinalizerIterator(ctx, inputs, opt, e.logger)
 	}
 
-	itrs, err := e.createVarRefIterator(measurement, opt)
+	itrs, err := e.createVarRefIterator(ctx, measurement, opt)
 	if err != nil {
 		return nil, err
 	}
-	return newMergeFinalizerIterator(itrs, opt, e.logger)
+	return newMergeFinalizerIterator(ctx, itrs, opt, e.logger)
 }
 
-func (e *Engine) createCallIterator(measurement string, call *influxql.Call, opt query.IteratorOptions) ([]query.Iterator, error) {
+func (e *Engine) createCallIterator(ctx context.Context, measurement string, call *influxql.Call, opt query.IteratorOptions) ([]query.Iterator, error) {
 	ref, _ := call.Args[0].(*influxql.VarRef)
 
 	if exists, err := e.index.MeasurementExists([]byte(measurement)); err != nil {
@@ -1745,7 +1774,7 @@ func (e *Engine) createCallIterator(measurement string, call *influxql.Call, opt
 			default:
 			}
 
-			inputs, err := e.createTagSetIterators(ref, measurement, t, opt)
+			inputs, err := e.createTagSetIterators(ctx, ref, measurement, t, opt)
 			if err != nil {
 				return err
 			} else if len(inputs) == 0 {
@@ -1779,7 +1808,7 @@ func (e *Engine) createCallIterator(measurement string, call *influxql.Call, opt
 }
 
 // createVarRefIterator creates an iterator for a variable reference.
-func (e *Engine) createVarRefIterator(measurement string, opt query.IteratorOptions) ([]query.Iterator, error) {
+func (e *Engine) createVarRefIterator(ctx context.Context, measurement string, opt query.IteratorOptions) ([]query.Iterator, error) {
 	ref, _ := opt.Expr.(*influxql.VarRef)
 
 	if exists, err := e.index.MeasurementExists([]byte(measurement)); err != nil {
@@ -1807,7 +1836,7 @@ func (e *Engine) createVarRefIterator(measurement string, opt query.IteratorOpti
 	itrs := make([]query.Iterator, 0, len(tagSets))
 	if err := func() error {
 		for _, t := range tagSets {
-			inputs, err := e.createTagSetIterators(ref, measurement, t, opt)
+			inputs, err := e.createTagSetIterators(ctx, ref, measurement, t, opt)
 			if err != nil {
 				return err
 			} else if len(inputs) == 0 {
@@ -1857,7 +1886,7 @@ func (e *Engine) createVarRefIterator(measurement string, opt query.IteratorOpti
 }
 
 // createTagSetIterators creates a set of iterators for a tagset.
-func (e *Engine) createTagSetIterators(ref *influxql.VarRef, name string, t *query.TagSet, opt query.IteratorOptions) ([]query.Iterator, error) {
+func (e *Engine) createTagSetIterators(ctx context.Context, ref *influxql.VarRef, name string, t *query.TagSet, opt query.IteratorOptions) ([]query.Iterator, error) {
 	// Set parallelism by number of logical cpus.
 	parallelism := runtime.GOMAXPROCS(0)
 	if parallelism > len(t.SeriesKeys) {
@@ -1892,7 +1921,7 @@ func (e *Engine) createTagSetIterators(ref *influxql.VarRef, name string, t *que
 		wg.Add(1)
 		go func(i int) {
 			defer wg.Done()
-			groups[i].itrs, groups[i].err = e.createTagSetGroupIterators(ref, name, groups[i].keys, t, groups[i].filters, opt)
+			groups[i].itrs, groups[i].err = e.createTagSetGroupIterators(ctx, ref, name, groups[i].keys, t, groups[i].filters, opt)
 		}(i)
 	}
 	wg.Wait()
@@ -1923,7 +1952,7 @@ func (e *Engine) createTagSetIterators(ref *influxql.VarRef, name string, t *que
 }
 
 // createTagSetGroupIterators creates a set of iterators for a subset of a tagset's series.
-func (e *Engine) createTagSetGroupIterators(ref *influxql.VarRef, name string, seriesKeys []string, t *query.TagSet, filters []influxql.Expr, opt query.IteratorOptions) ([]query.Iterator, error) {
+func (e *Engine) createTagSetGroupIterators(ctx context.Context, ref *influxql.VarRef, name string, seriesKeys []string, t *query.TagSet, filters []influxql.Expr, opt query.IteratorOptions) ([]query.Iterator, error) {
 	itrs := make([]query.Iterator, 0, len(seriesKeys))
 	for i, seriesKey := range seriesKeys {
 		var conditionFields []influxql.VarRef
@@ -1932,7 +1961,7 @@ func (e *Engine) createTagSetGroupIterators(ref *influxql.VarRef, name string, s
 			conditionFields = influxql.ExprNames(filters[i])
 		}
 
-		itr, err := e.createVarRefSeriesIterator(ref, name, seriesKey, t, filters[i], conditionFields, opt)
+		itr, err := e.createVarRefSeriesIterator(ctx, ref, name, seriesKey, t, filters[i], conditionFields, opt)
 		if err != nil {
 			return itrs, err
 		} else if itr == nil {
@@ -1959,7 +1988,7 @@ func (e *Engine) createTagSetGroupIterators(ref *influxql.VarRef, name string, s
 }
 
 // createVarRefSeriesIterator creates an iterator for a variable reference for a series.
-func (e *Engine) createVarRefSeriesIterator(ref *influxql.VarRef, name string, seriesKey string, t *query.TagSet, filter influxql.Expr, conditionFields []influxql.VarRef, opt query.IteratorOptions) (query.Iterator, error) {
+func (e *Engine) createVarRefSeriesIterator(ctx context.Context, ref *influxql.VarRef, name string, seriesKey string, t *query.TagSet, filter influxql.Expr, conditionFields []influxql.VarRef, opt query.IteratorOptions) (query.Iterator, error) {
 	_, tfs := models.ParseKey([]byte(seriesKey))
 	tags := query.NewTags(tfs.Map())
 
@@ -1967,6 +1996,26 @@ func (e *Engine) createVarRefSeriesIterator(ref *influxql.VarRef, name string, s
 	itrOpt := opt
 	itrOpt.Condition = filter
 
+	var curCounter, auxCounter, condCounter *metrics.Counter
+	if col := metrics.GroupFromContext(ctx); col != nil {
+		curCounter = col.GetCounter(numberOfRefCursorsCounter)
+		auxCounter = col.GetCounter(numberOfAuxCursorsCounter)
+		condCounter = col.GetCounter(numberOfCondCursorsCounter)
+	}
+
+	// Build main cursor.
+	var cur cursor
+	if ref != nil {
+		cur = e.buildCursor(ctx, name, seriesKey, tfs, ref, opt)
+		// If the field doesn't exist then don't build an iterator.
+		if cur == nil {
+			return nil, nil
+		}
+		if curCounter != nil {
+			curCounter.Add(1)
+		}
+	}
+
 	// Build auxilary cursors.
 	// Tag values should be returned if the field doesn't exist.
 	var aux []cursorAt
@@ -1975,8 +2024,11 @@ func (e *Engine) createVarRefSeriesIterator(ref *influxql.VarRef, name string, s
 		for i, ref := range opt.Aux {
 			// Create cursor from field if a tag wasn't requested.
 			if ref.Type != influxql.Tag {
-				cur := e.buildCursor(name, seriesKey, tfs, &ref, opt)
+				cur := e.buildCursor(ctx, name, seriesKey, tfs, &ref, opt)
 				if cur != nil {
+					if auxCounter != nil {
+						auxCounter.Add(1)
+					}
 					aux[i] = newBufCursor(cur, opt.Ascending)
 					continue
 				}
@@ -2039,8 +2091,11 @@ func (e *Engine) createVarRefSeriesIterator(ref *influxql.VarRef, name string, s
 		for i, ref := range conditionFields {
 			// Create cursor from field if a tag wasn't requested.
 			if ref.Type != influxql.Tag {
-				cur := e.buildCursor(name, seriesKey, tfs, &ref, opt)
+				cur := e.buildCursor(ctx, name, seriesKey, tfs, &ref, opt)
 				if cur != nil {
+					if condCounter != nil {
+						condCounter.Add(1)
+					}
 					conds[i] = newBufCursor(cur, opt.Ascending)
 					continue
 				}
@@ -2088,16 +2143,6 @@ func (e *Engine) createVarRefSeriesIterator(ref *influxql.VarRef, name string, s
 		return newFloatIterator(name, tags, itrOpt, nil, aux, conds, condNames), nil
 	}
 
-	// Build main cursor.
-	cur := e.buildCursor(name, seriesKey, tfs, ref, opt)
-
-	// If the field doesn't exist then don't build an iterator.
-	if cur == nil {
-		cursorsAt(aux).close()
-		cursorsAt(conds).close()
-		return nil, nil
-	}
-
 	// Remove name if requested.
 	if opt.StripName {
 		name = ""
@@ -2120,7 +2165,7 @@ func (e *Engine) createVarRefSeriesIterator(ref *influxql.VarRef, name string, s
 }
 
 // buildCursor creates an untyped cursor for a field.
-func (e *Engine) buildCursor(measurement, seriesKey string, tags models.Tags, ref *influxql.VarRef, opt query.IteratorOptions) cursor {
+func (e *Engine) buildCursor(ctx context.Context, measurement, seriesKey string, tags models.Tags, ref *influxql.VarRef, opt query.IteratorOptions) cursor {
 	// Check if this is a system field cursor.
 	switch ref.Val {
 	case "_name":
@@ -2157,28 +2202,28 @@ func (e *Engine) buildCursor(measurement, seriesKey string, tags models.Tags, re
 		case influxql.Float:
 			switch f.Type {
 			case influxql.Integer:
-				cur := e.buildIntegerCursor(measurement, seriesKey, ref.Val, opt)
+				cur := e.buildIntegerCursor(ctx, measurement, seriesKey, ref.Val, opt)
 				return &floatCastIntegerCursor{cursor: cur}
 			case influxql.Unsigned:
-				cur := e.buildUnsignedCursor(measurement, seriesKey, ref.Val, opt)
+				cur := e.buildUnsignedCursor(ctx, measurement, seriesKey, ref.Val, opt)
 				return &floatCastUnsignedCursor{cursor: cur}
 			}
 		case influxql.Integer:
 			switch f.Type {
 			case influxql.Float:
-				cur := e.buildFloatCursor(measurement, seriesKey, ref.Val, opt)
+				cur := e.buildFloatCursor(ctx, measurement, seriesKey, ref.Val, opt)
 				return &integerCastFloatCursor{cursor: cur}
 			case influxql.Unsigned:
-				cur := e.buildUnsignedCursor(measurement, seriesKey, ref.Val, opt)
+				cur := e.buildUnsignedCursor(ctx, measurement, seriesKey, ref.Val, opt)
 				return &integerCastUnsignedCursor{cursor: cur}
 			}
 		case influxql.Unsigned:
 			switch f.Type {
 			case influxql.Float:
-				cur := e.buildFloatCursor(measurement, seriesKey, ref.Val, opt)
+				cur := e.buildFloatCursor(ctx, measurement, seriesKey, ref.Val, opt)
 				return &unsignedCastFloatCursor{cursor: cur}
 			case influxql.Integer:
-				cur := e.buildIntegerCursor(measurement, seriesKey, ref.Val, opt)
+				cur := e.buildIntegerCursor(ctx, measurement, seriesKey, ref.Val, opt)
 				return &unsignedCastIntegerCursor{cursor: cur}
 			}
 		}
@@ -2188,15 +2233,15 @@ func (e *Engine) buildCursor(measurement, seriesKey string, tags models.Tags, re
 	// Return appropriate cursor based on type.
 	switch f.Type {
 	case influxql.Float:
-		return e.buildFloatCursor(measurement, seriesKey, ref.Val, opt)
+		return e.buildFloatCursor(ctx, measurement, seriesKey, ref.Val, opt)
 	case influxql.Integer:
-		return e.buildIntegerCursor(measurement, seriesKey, ref.Val, opt)
+		return e.buildIntegerCursor(ctx, measurement, seriesKey, ref.Val, opt)
 	case influxql.Unsigned:
-		return e.buildUnsignedCursor(measurement, seriesKey, ref.Val, opt)
+		return e.buildUnsignedCursor(ctx, measurement, seriesKey, ref.Val, opt)
 	case influxql.String:
-		return e.buildStringCursor(measurement, seriesKey, ref.Val, opt)
+		return e.buildStringCursor(ctx, measurement, seriesKey, ref.Val, opt)
 	case influxql.Boolean:
-		return e.buildBooleanCursor(measurement, seriesKey, ref.Val, opt)
+		return e.buildBooleanCursor(ctx, measurement, seriesKey, ref.Val, opt)
 	default:
 		panic("unreachable")
 	}
@@ -2225,42 +2270,42 @@ func matchTagValues(tags models.Tags, condition influxql.Expr) []string {
 }
 
 // buildFloatCursor creates a cursor for a float field.
-func (e *Engine) buildFloatCursor(measurement, seriesKey, field string, opt query.IteratorOptions) floatCursor {
+func (e *Engine) buildFloatCursor(ctx context.Context, measurement, seriesKey, field string, opt query.IteratorOptions) floatCursor {
 	key := SeriesFieldKeyBytes(seriesKey, field)
 	cacheValues := e.Cache.Values(key)
-	keyCursor := e.KeyCursor(key, opt.SeekTime(), opt.Ascending)
+	keyCursor := e.KeyCursor(ctx, key, opt.SeekTime(), opt.Ascending)
 	return newFloatCursor(opt.SeekTime(), opt.Ascending, cacheValues, keyCursor)
 }
 
 // buildIntegerCursor creates a cursor for an integer field.
-func (e *Engine) buildIntegerCursor(measurement, seriesKey, field string, opt query.IteratorOptions) integerCursor {
+func (e *Engine) buildIntegerCursor(ctx context.Context, measurement, seriesKey, field string, opt query.IteratorOptions) integerCursor {
 	key := SeriesFieldKeyBytes(seriesKey, field)
 	cacheValues := e.Cache.Values(key)
-	keyCursor := e.KeyCursor(key, opt.SeekTime(), opt.Ascending)
+	keyCursor := e.KeyCursor(ctx, key, opt.SeekTime(), opt.Ascending)
 	return newIntegerCursor(opt.SeekTime(), opt.Ascending, cacheValues, keyCursor)
 }
 
 // buildUnsignedCursor creates a cursor for an unsigned field.
-func (e *Engine) buildUnsignedCursor(measurement, seriesKey, field string, opt query.IteratorOptions) unsignedCursor {
+func (e *Engine) buildUnsignedCursor(ctx context.Context, measurement, seriesKey, field string, opt query.IteratorOptions) unsignedCursor {
 	key := SeriesFieldKeyBytes(seriesKey, field)
 	cacheValues := e.Cache.Values(key)
-	keyCursor := e.KeyCursor(key, opt.SeekTime(), opt.Ascending)
+	keyCursor := e.KeyCursor(ctx, key, opt.SeekTime(), opt.Ascending)
 	return newUnsignedCursor(opt.SeekTime(), opt.Ascending, cacheValues, keyCursor)
 }
 
 // buildStringCursor creates a cursor for a string field.
-func (e *Engine) buildStringCursor(measurement, seriesKey, field string, opt query.IteratorOptions) stringCursor {
+func (e *Engine) buildStringCursor(ctx context.Context, measurement, seriesKey, field string, opt query.IteratorOptions) stringCursor {
 	key := SeriesFieldKeyBytes(seriesKey, field)
 	cacheValues := e.Cache.Values(key)
-	keyCursor := e.KeyCursor(key, opt.SeekTime(), opt.Ascending)
+	keyCursor := e.KeyCursor(ctx, key, opt.SeekTime(), opt.Ascending)
 	return newStringCursor(opt.SeekTime(), opt.Ascending, cacheValues, keyCursor)
 }
 
 // buildBooleanCursor creates a cursor for a boolean field.
-func (e *Engine) buildBooleanCursor(measurement, seriesKey, field string, opt query.IteratorOptions) booleanCursor {
+func (e *Engine) buildBooleanCursor(ctx context.Context, measurement, seriesKey, field string, opt query.IteratorOptions) booleanCursor {
 	key := SeriesFieldKeyBytes(seriesKey, field)
 	cacheValues := e.Cache.Values(key)
-	keyCursor := e.KeyCursor(key, opt.SeekTime(), opt.Ascending)
+	keyCursor := e.KeyCursor(ctx, key, opt.SeekTime(), opt.Ascending)
 	return newBooleanCursor(opt.SeekTime(), opt.Ascending, cacheValues, keyCursor)
 }
 

tsdb/engine/tsm1/engine_test.go

@@ -3,6 +3,7 @@ package tsm1_test
 import (
 	"archive/tar"
 	"bytes"
+	"context"
 	"fmt"
 	"io"
 	"io/ioutil"
@@ -269,7 +270,7 @@ func TestEngine_CreateIterator_Cache_Ascending(t *testing.T) {
 		t.Fatalf("failed to write points: %s", err.Error())
 	}
 
-	itr, err := e.CreateIterator("cpu", query.IteratorOptions{
+	itr, err := e.CreateIterator(context.Background(), "cpu", query.IteratorOptions{
 		Expr:       influxql.MustParseExpr(`value`),
 		Dimensions: []string{"host"},
 		StartTime:  influxql.MinTime,
@@ -321,7 +322,7 @@ func TestEngine_CreateIterator_Cache_Descending(t *testing.T) {
 		t.Fatalf("failed to write points: %s", err.Error())
 	}
 
-	itr, err := e.CreateIterator("cpu", query.IteratorOptions{
+	itr, err := e.CreateIterator(context.Background(), "cpu", query.IteratorOptions{
 		Expr:       influxql.MustParseExpr(`value`),
 		Dimensions: []string{"host"},
 		StartTime:  influxql.MinTime,
@@ -374,7 +375,7 @@ func TestEngine_CreateIterator_TSM_Ascending(t *testing.T) {
 	}
 	e.MustWriteSnapshot()
 
-	itr, err := e.CreateIterator("cpu", query.IteratorOptions{
+	itr, err := e.CreateIterator(context.Background(), "cpu", query.IteratorOptions{
 		Expr:       influxql.MustParseExpr(`value`),
 		Dimensions: []string{"host"},
 		StartTime:  influxql.MinTime,
@@ -427,7 +428,7 @@ func TestEngine_CreateIterator_TSM_Descending(t *testing.T) {
 	}
 	e.MustWriteSnapshot()
 
-	itr, err := e.CreateIterator("cpu", query.IteratorOptions{
+	itr, err := e.CreateIterator(context.Background(), "cpu", query.IteratorOptions{
 		Expr:       influxql.MustParseExpr(`value`),
 		Dimensions: []string{"host"},
 		StartTime:  influxql.MinTime,
@@ -482,7 +483,7 @@ func TestEngine_CreateIterator_Aux(t *testing.T) {
 		t.Fatalf("failed to write points: %s", err.Error())
 	}
 
-	itr, err := e.CreateIterator("cpu", query.IteratorOptions{
+	itr, err := e.CreateIterator(context.Background(), "cpu", query.IteratorOptions{
 		Expr:       influxql.MustParseExpr(`value`),
 		Aux:        []influxql.VarRef{{Val: "F"}},
 		Dimensions: []string{"host"},
@@ -545,7 +546,7 @@ func TestEngine_CreateIterator_Condition(t *testing.T) {
 		t.Fatalf("failed to write points: %s", err.Error())
 	}
 
-	itr, err := e.CreateIterator("cpu", query.IteratorOptions{
+	itr, err := e.CreateIterator(context.Background(), "cpu", query.IteratorOptions{
 		Expr:       influxql.MustParseExpr(`value`),
 		Dimensions: []string{"host"},
 		Condition:  influxql.MustParseExpr(`X = 10 OR Y > 150`),
@@ -874,7 +875,7 @@ func benchmarkIterator(b *testing.B, opt query.IteratorOptions, pointN int) {
 	b.ReportAllocs()
 
 	for i := 0; i < b.N; i++ {
-		itr, err := e.CreateIterator("cpu", opt)
+		itr, err := e.CreateIterator(context.Background(), "cpu", opt)
 		if err != nil {
 			b.Fatal(err)
 		}

tsdb/engine/tsm1/file_store.gen.go

@@ -20,6 +20,10 @@ func (c *KeyCursor) ReadFloatBlock(buf *[]FloatValue) ([]FloatValue, error) {
 	if err != nil {
 		return nil, err
 	}
+	if c.col != nil {
+		c.col.GetCounter(floatBlocksDecodedCounter).Add(1)
+		c.col.GetCounter(floatBlocksSizeCounter).Add(int64(first.entry.Size))
+	}
 
 	// Remove values we already read
 	values = FloatValues(values).Exclude(first.readMin, first.readMax)
@@ -88,6 +92,11 @@ func (c *KeyCursor) ReadFloatBlock(buf *[]FloatValue) ([]FloatValue, error) {
 			if err != nil {
 				return nil, err
 			}
+			if c.col != nil {
+				c.col.GetCounter(floatBlocksDecodedCounter).Add(1)
+				c.col.GetCounter(floatBlocksSizeCounter).Add(int64(cur.entry.Size))
+			}
+
 			// Remove any tombstoned values
 			v = c.filterFloatValues(tombstones, v)
 
@@ -147,6 +156,11 @@ func (c *KeyCursor) ReadFloatBlock(buf *[]FloatValue) ([]FloatValue, error) {
 			if err != nil {
 				return nil, err
 			}
+			if c.col != nil {
+				c.col.GetCounter(floatBlocksDecodedCounter).Add(1)
+				c.col.GetCounter(floatBlocksSizeCounter).Add(int64(cur.entry.Size))
+			}
+
 			// Remove any tombstoned values
 			v = c.filterFloatValues(tombstones, v)
 
@@ -183,6 +197,10 @@ func (c *KeyCursor) ReadIntegerBlock(buf *[]IntegerValue) ([]IntegerValue, error
 	if err != nil {
 		return nil, err
 	}
+	if c.col != nil {
+		c.col.GetCounter(integerBlocksDecodedCounter).Add(1)
+		c.col.GetCounter(integerBlocksSizeCounter).Add(int64(first.entry.Size))
+	}
 
 	// Remove values we already read
 	values = IntegerValues(values).Exclude(first.readMin, first.readMax)
@@ -251,6 +269,11 @@ func (c *KeyCursor) ReadIntegerBlock(buf *[]IntegerValue) ([]IntegerValue, error
 			if err != nil {
 				return nil, err
 			}
+			if c.col != nil {
+				c.col.GetCounter(integerBlocksDecodedCounter).Add(1)
+				c.col.GetCounter(integerBlocksSizeCounter).Add(int64(cur.entry.Size))
+			}
+
 			// Remove any tombstoned values
 			v = c.filterIntegerValues(tombstones, v)
 
@@ -310,6 +333,11 @@ func (c *KeyCursor) ReadIntegerBlock(buf *[]IntegerValue) ([]IntegerValue, error
 			if err != nil {
 				return nil, err
 			}
+			if c.col != nil {
+				c.col.GetCounter(integerBlocksDecodedCounter).Add(1)
+				c.col.GetCounter(integerBlocksSizeCounter).Add(int64(cur.entry.Size))
+			}
+
 			// Remove any tombstoned values
 			v = c.filterIntegerValues(tombstones, v)
 
@@ -346,6 +374,10 @@ func (c *KeyCursor) ReadUnsignedBlock(buf *[]UnsignedValue) ([]UnsignedValue, er
 	if err != nil {
 		return nil, err
 	}
+	if c.col != nil {
+		c.col.GetCounter(unsignedBlocksDecodedCounter).Add(1)
+		c.col.GetCounter(unsignedBlocksSizeCounter).Add(int64(first.entry.Size))
+	}
 
 	// Remove values we already read
 	values = UnsignedValues(values).Exclude(first.readMin, first.readMax)
@@ -414,6 +446,11 @@ func (c *KeyCursor) ReadUnsignedBlock(buf *[]UnsignedValue) ([]UnsignedValue, er
 			if err != nil {
 				return nil, err
 			}
+			if c.col != nil {
+				c.col.GetCounter(unsignedBlocksDecodedCounter).Add(1)
+				c.col.GetCounter(unsignedBlocksSizeCounter).Add(int64(cur.entry.Size))
+			}
+
 			// Remove any tombstoned values
 			v = c.filterUnsignedValues(tombstones, v)
 
@@ -473,6 +510,11 @@ func (c *KeyCursor) ReadUnsignedBlock(buf *[]UnsignedValue) ([]UnsignedValue, er
 			if err != nil {
 				return nil, err
 			}
+			if c.col != nil {
+				c.col.GetCounter(unsignedBlocksDecodedCounter).Add(1)
+				c.col.GetCounter(unsignedBlocksSizeCounter).Add(int64(cur.entry.Size))
+			}
+
 			// Remove any tombstoned values
 			v = c.filterUnsignedValues(tombstones, v)
 
@@ -509,6 +551,10 @@ func (c *KeyCursor) ReadStringBlock(buf *[]StringValue) ([]StringValue, error) {
 	if err != nil {
 		return nil, err
 	}
+	if c.col != nil {
+		c.col.GetCounter(stringBlocksDecodedCounter).Add(1)
+		c.col.GetCounter(stringBlocksSizeCounter).Add(int64(first.entry.Size))
+	}
 
 	// Remove values we already read
 	values = StringValues(values).Exclude(first.readMin, first.readMax)
@@ -577,6 +623,11 @@ func (c *KeyCursor) ReadStringBlock(buf *[]StringValue) ([]StringValue, error) {
 			if err != nil {
 				return nil, err
 			}
+			if c.col != nil {
+				c.col.GetCounter(stringBlocksDecodedCounter).Add(1)
+				c.col.GetCounter(stringBlocksSizeCounter).Add(int64(cur.entry.Size))
+			}
+
 			// Remove any tombstoned values
 			v = c.filterStringValues(tombstones, v)
 
@@ -636,6 +687,11 @@ func (c *KeyCursor) ReadStringBlock(buf *[]StringValue) ([]StringValue, error) {
 			if err != nil {
 				return nil, err
 			}
+			if c.col != nil {
+				c.col.GetCounter(stringBlocksDecodedCounter).Add(1)
+				c.col.GetCounter(stringBlocksSizeCounter).Add(int64(cur.entry.Size))
+			}
+
 			// Remove any tombstoned values
 			v = c.filterStringValues(tombstones, v)
 
@@ -672,6 +728,10 @@ func (c *KeyCursor) ReadBooleanBlock(buf *[]BooleanValue) ([]BooleanValue, error
 	if err != nil {
 		return nil, err
 	}
+	if c.col != nil {
+		c.col.GetCounter(booleanBlocksDecodedCounter).Add(1)
+		c.col.GetCounter(booleanBlocksSizeCounter).Add(int64(first.entry.Size))
+	}
 
 	// Remove values we already read
 	values = BooleanValues(values).Exclude(first.readMin, first.readMax)
@@ -740,6 +800,11 @@ func (c *KeyCursor) ReadBooleanBlock(buf *[]BooleanValue) ([]BooleanValue, error
 			if err != nil {
 				return nil, err
 			}
+			if c.col != nil {
+				c.col.GetCounter(booleanBlocksDecodedCounter).Add(1)
+				c.col.GetCounter(booleanBlocksSizeCounter).Add(int64(cur.entry.Size))
+			}
+
 			// Remove any tombstoned values
 			v = c.filterBooleanValues(tombstones, v)
 
@@ -799,6 +864,11 @@ func (c *KeyCursor) ReadBooleanBlock(buf *[]BooleanValue) ([]BooleanValue, error
 			if err != nil {
 				return nil, err
 			}
+			if c.col != nil {
+				c.col.GetCounter(booleanBlocksDecodedCounter).Add(1)
+				c.col.GetCounter(booleanBlocksSizeCounter).Add(int64(cur.entry.Size))
+			}
+
 			// Remove any tombstoned values
 			v = c.filterBooleanValues(tombstones, v)
 

tsdb/engine/tsm1/file_store.gen.go.tmpl

@@ -16,6 +16,10 @@ func (c *KeyCursor) Read{{.Name}}Block(buf *[]{{.Name}}Value) ([]{{.Name}}Value,
 	if err != nil {
 		return nil, err
 	}
+	if c.col != nil {
+		c.col.GetCounter({{.name}}BlocksDecodedCounter).Add(1)
+		c.col.GetCounter({{.name}}BlocksSizeCounter).Add(int64(first.entry.Size))
+	}
 
 	// Remove values we already read
 	values = {{.Name}}Values(values).Exclude(first.readMin, first.readMax)
@@ -84,6 +88,11 @@ func (c *KeyCursor) Read{{.Name}}Block(buf *[]{{.Name}}Value) ([]{{.Name}}Value,
 			if err != nil {
 				return nil, err
 			}
+			if c.col != nil {
+				c.col.GetCounter({{.name}}BlocksDecodedCounter).Add(1)
+				c.col.GetCounter({{.name}}BlocksSizeCounter).Add(int64(cur.entry.Size))
+			}
+
 			// Remove any tombstoned values
 			v = c.filter{{.Name}}Values(tombstones, v)
 
@@ -143,6 +152,11 @@ func (c *KeyCursor) Read{{.Name}}Block(buf *[]{{.Name}}Value) ([]{{.Name}}Value,
 			if err != nil {
 				return nil, err
 			}
+			if c.col != nil {
+				c.col.GetCounter({{.name}}BlocksDecodedCounter).Add(1)
+				c.col.GetCounter({{.name}}BlocksSizeCounter).Add(int64(cur.entry.Size))
+			}
+
 			// Remove any tombstoned values
 			v = c.filter{{.Name}}Values(tombstones, v)
 

tsdb/engine/tsm1/file_store.go

@@ -2,6 +2,7 @@ package tsm1
 
 import (
 	"bytes"
+	"context"
 	"fmt"
 	"io/ioutil"
 	"math"
@@ -15,6 +16,7 @@ import (
 	"time"
 
 	"github.com/influxdata/influxdb/models"
+	"github.com/influxdata/influxdb/pkg/metrics"
 	"github.com/influxdata/influxdb/query"
 	"github.com/uber-go/zap"
 )
@@ -120,6 +122,19 @@ const (
 	statFileStoreCount = "numFiles"
 )
 
+var (
+	floatBlocksDecodedCounter    = metrics.MustRegisterCounter("float_blocks_decoded", metrics.WithGroup(tsmGroup))
+	floatBlocksSizeCounter       = metrics.MustRegisterCounter("float_blocks_size_bytes", metrics.WithGroup(tsmGroup))
+	integerBlocksDecodedCounter  = metrics.MustRegisterCounter("integer_blocks_decoded", metrics.WithGroup(tsmGroup))
+	integerBlocksSizeCounter     = metrics.MustRegisterCounter("integer_blocks_size_bytes", metrics.WithGroup(tsmGroup))
+	unsignedBlocksDecodedCounter = metrics.MustRegisterCounter("unsigned_blocks_decoded", metrics.WithGroup(tsmGroup))
+	unsignedBlocksSizeCounter    = metrics.MustRegisterCounter("unsigned_blocks_size_bytes", metrics.WithGroup(tsmGroup))
+	stringBlocksDecodedCounter   = metrics.MustRegisterCounter("string_blocks_decoded", metrics.WithGroup(tsmGroup))
+	stringBlocksSizeCounter      = metrics.MustRegisterCounter("string_blocks_size_bytes", metrics.WithGroup(tsmGroup))
+	booleanBlocksDecodedCounter  = metrics.MustRegisterCounter("boolean_blocks_decoded", metrics.WithGroup(tsmGroup))
+	booleanBlocksSizeCounter     = metrics.MustRegisterCounter("boolean_blocks_size_bytes", metrics.WithGroup(tsmGroup))
+)
+
 // FileStore is an abstraction around multiple TSM files.
 type FileStore struct {
 	mu           sync.RWMutex
@@ -509,10 +524,10 @@ func (f *FileStore) TSMReader(path string) *TSMReader {
 }
 
 // KeyCursor returns a KeyCursor for key and t across the files in the FileStore.
-func (f *FileStore) KeyCursor(key []byte, t int64, ascending bool) *KeyCursor {
+func (f *FileStore) KeyCursor(ctx context.Context, key []byte, t int64, ascending bool) *KeyCursor {
 	f.mu.RLock()
 	defer f.mu.RUnlock()
-	return newKeyCursor(f, key, t, ascending)
+	return newKeyCursor(ctx, f, key, t, ascending)
 }
 
 // Stats returns the stats of the underlying files, preferring the cached version if it is still valid.
@@ -952,6 +967,9 @@ type KeyCursor struct {
 	current []*location
 	buf     []Value
 
+	ctx context.Context
+	col *metrics.Group
+
 	// pos is the index within seeks.  Based on ascending, it will increment or
 	// decrement through the size of seeks slice.
 	pos       int
@@ -1011,10 +1029,12 @@ func (a ascLocations) Less(i, j int) bool {
 
 // newKeyCursor returns a new instance of KeyCursor.
 // This function assumes the read-lock has been taken.
-func newKeyCursor(fs *FileStore, key []byte, t int64, ascending bool) *KeyCursor {
+func newKeyCursor(ctx context.Context, fs *FileStore, key []byte, t int64, ascending bool) *KeyCursor {
 	c := &KeyCursor{
 		key:       key,
 		seeks:     fs.locations(key, t, ascending),
+		ctx:       ctx,
+		col:       metrics.GroupFromContext(ctx),
 		ascending: ascending,
 	}
 

tsdb/engine/tsm1/file_store_test.go

@@ -1,6 +1,7 @@
 package tsm1_test
 
 import (
+	"context"
 	"fmt"
 	"io/ioutil"
 	"os"
@@ -71,7 +72,7 @@ func TestFileStore_SeekToAsc_FromStart(t *testing.T) {
 	fs.Replace(nil, files)
 
 	buf := make([]tsm1.FloatValue, 1000)
-	c := fs.KeyCursor([]byte("cpu"), 0, true)
+	c := fs.KeyCursor(context.Background(), []byte("cpu"), 0, true)
 	// Search for an entry that exists in the second file
 	values, err := c.ReadFloatBlock(&buf)
 	if err != nil {
@@ -111,7 +112,7 @@ func TestFileStore_SeekToAsc_Duplicate(t *testing.T) {
 	fs.Replace(nil, files)
 
 	buf := make([]tsm1.FloatValue, 1000)
-	c := fs.KeyCursor([]byte("cpu"), 0, true)
+	c := fs.KeyCursor(context.Background(), []byte("cpu"), 0, true)
 	// Search for an entry that exists in the second file
 	values, err := c.ReadFloatBlock(&buf)
 	if err != nil {
@@ -184,7 +185,7 @@ func TestFileStore_SeekToAsc_BeforeStart(t *testing.T) {
 
 	// Search for an entry that exists in the second file
 	buf := make([]tsm1.FloatValue, 1000)
-	c := fs.KeyCursor([]byte("cpu"), 0, true)
+	c := fs.KeyCursor(context.Background(), []byte("cpu"), 0, true)
 	values, err := c.ReadFloatBlock(&buf)
 	if err != nil {
 		t.Fatalf("unexpected error reading values: %v", err)
@@ -226,7 +227,7 @@ func TestFileStore_SeekToAsc_BeforeStart_OverlapFloat(t *testing.T) {
 
 	// Search for an entry that exists in the second file
 	buf := make([]tsm1.FloatValue, 1000)
-	c := fs.KeyCursor([]byte("cpu"), 0, true)
+	c := fs.KeyCursor(context.Background(), []byte("cpu"), 0, true)
 	values, err := c.ReadFloatBlock(&buf)
 	if err != nil {
 		t.Fatalf("unexpected error reading values: %v", err)
@@ -293,7 +294,7 @@ func TestFileStore_SeekToAsc_BeforeStart_OverlapInteger(t *testing.T) {
 
 	// Search for an entry that exists in the second file
 	buf := make([]tsm1.IntegerValue, 1000)
-	c := fs.KeyCursor([]byte("cpu"), 0, true)
+	c := fs.KeyCursor(context.Background(), []byte("cpu"), 0, true)
 	values, err := c.ReadIntegerBlock(&buf)
 	if err != nil {
 		t.Fatalf("unexpected error reading values: %v", err)
@@ -359,7 +360,7 @@ func TestFileStore_SeekToAsc_BeforeStart_OverlapUnsigned(t *testing.T) {
 
 	// Search for an entry that exists in the second file
 	buf := make([]tsm1.UnsignedValue, 1000)
-	c := fs.KeyCursor([]byte("cpu"), 0, true)
+	c := fs.KeyCursor(context.Background(), []byte("cpu"), 0, true)
 	values, err := c.ReadUnsignedBlock(&buf)
 	if err != nil {
 		t.Fatalf("unexpected error reading values: %v", err)
@@ -425,7 +426,7 @@ func TestFileStore_SeekToAsc_BeforeStart_OverlapBoolean(t *testing.T) {
 
 	// Search for an entry that exists in the second file
 	buf := make([]tsm1.BooleanValue, 1000)
-	c := fs.KeyCursor([]byte("cpu"), 0, true)
+	c := fs.KeyCursor(context.Background(), []byte("cpu"), 0, true)
 	values, err := c.ReadBooleanBlock(&buf)
 	if err != nil {
 		t.Fatalf("unexpected error reading values: %v", err)
@@ -491,7 +492,7 @@ func TestFileStore_SeekToAsc_BeforeStart_OverlapString(t *testing.T) {
 
 	// Search for an entry that exists in the second file
 	buf := make([]tsm1.StringValue, 1000)
-	c := fs.KeyCursor([]byte("cpu"), 0, true)
+	c := fs.KeyCursor(context.Background(), []byte("cpu"), 0, true)
 	values, err := c.ReadStringBlock(&buf)
 	if err != nil {
 		t.Fatalf("unexpected error reading values: %v", err)
@@ -556,7 +557,7 @@ func TestFileStore_SeekToAsc_OverlapMinFloat(t *testing.T) {
 	fs.Replace(nil, files)
 
 	buf := make([]tsm1.FloatValue, 1000)
-	c := fs.KeyCursor([]byte("cpu"), 0, true)
+	c := fs.KeyCursor(context.Background(), []byte("cpu"), 0, true)
 	// Search for an entry that exists in the second file
 	values, err := c.ReadFloatBlock(&buf)
 	if err != nil {
@@ -636,7 +637,7 @@ func TestFileStore_SeekToAsc_OverlapMinInteger(t *testing.T) {
 	fs.Replace(nil, files)
 
 	buf := make([]tsm1.IntegerValue, 1000)
-	c := fs.KeyCursor([]byte("cpu"), 0, true)
+	c := fs.KeyCursor(context.Background(), []byte("cpu"), 0, true)
 	// Search for an entry that exists in the second file
 	values, err := c.ReadIntegerBlock(&buf)
 	if err != nil {
@@ -715,7 +716,7 @@ func TestFileStore_SeekToAsc_OverlapMinUnsigned(t *testing.T) {
 	fs.Replace(nil, files)
 
 	buf := make([]tsm1.UnsignedValue, 1000)
-	c := fs.KeyCursor([]byte("cpu"), 0, true)
+	c := fs.KeyCursor(context.Background(), []byte("cpu"), 0, true)
 	// Search for an entry that exists in the second file
 	values, err := c.ReadUnsignedBlock(&buf)
 	if err != nil {
@@ -794,7 +795,7 @@ func TestFileStore_SeekToAsc_OverlapMinBoolean(t *testing.T) {
 	fs.Replace(nil, files)
 
 	buf := make([]tsm1.BooleanValue, 1000)
-	c := fs.KeyCursor([]byte("cpu"), 0, true)
+	c := fs.KeyCursor(context.Background(), []byte("cpu"), 0, true)
 	// Search for an entry that exists in the second file
 	values, err := c.ReadBooleanBlock(&buf)
 	if err != nil {
@@ -873,7 +874,7 @@ func TestFileStore_SeekToAsc_OverlapMinString(t *testing.T) {
 	fs.Replace(nil, files)
 
 	buf := make([]tsm1.StringValue, 1000)
-	c := fs.KeyCursor([]byte("cpu"), 0, true)
+	c := fs.KeyCursor(context.Background(), []byte("cpu"), 0, true)
 	// Search for an entry that exists in the second file
 	values, err := c.ReadStringBlock(&buf)
 	if err != nil {
@@ -951,7 +952,7 @@ func TestFileStore_SeekToAsc_Middle(t *testing.T) {
 
 	// Search for an entry that exists in the second file
 	buf := make([]tsm1.FloatValue, 1000)
-	c := fs.KeyCursor([]byte("cpu"), 3, true)
+	c := fs.KeyCursor(context.Background(), []byte("cpu"), 3, true)
 	values, err := c.ReadFloatBlock(&buf)
 	if err != nil {
 		t.Fatalf("unexpected error reading values: %v", err)
@@ -1007,7 +1008,7 @@ func TestFileStore_SeekToAsc_End(t *testing.T) {
 	fs.Replace(nil, files)
 
 	buf := make([]tsm1.FloatValue, 1000)
-	c := fs.KeyCursor([]byte("cpu"), 2, true)
+	c := fs.KeyCursor(context.Background(), []byte("cpu"), 2, true)
 	values, err := c.ReadFloatBlock(&buf)
 	if err != nil {
 		t.Fatalf("unexpected error reading values: %v", err)
@@ -1046,7 +1047,7 @@ func TestFileStore_SeekToDesc_FromStart(t *testing.T) {
 
 	// Search for an entry that exists in the second file
 	buf := make([]tsm1.FloatValue, 1000)
-	c := fs.KeyCursor([]byte("cpu"), 0, false)
+	c := fs.KeyCursor(context.Background(), []byte("cpu"), 0, false)
 	values, err := c.ReadFloatBlock(&buf)
 	if err != nil {
 		t.Fatalf("unexpected error reading values: %v", err)
@@ -1085,7 +1086,7 @@ func TestFileStore_SeekToDesc_Duplicate(t *testing.T) {
 
 	// Search for an entry that exists in the second file
 	buf := make([]tsm1.FloatValue, 1000)
-	c := fs.KeyCursor([]byte("cpu"), 2, false)
+	c := fs.KeyCursor(context.Background(), []byte("cpu"), 2, false)
 	values, err := c.ReadFloatBlock(&buf)
 	if err != nil {
 		t.Fatalf("unexpected error reading values: %v", err)
@@ -1144,7 +1145,7 @@ func TestFileStore_SeekToDesc_OverlapMaxFloat(t *testing.T) {
 
 	// Search for an entry that exists in the second file
 	buf := make([]tsm1.FloatValue, 1000)
-	c := fs.KeyCursor([]byte("cpu"), 5, false)
+	c := fs.KeyCursor(context.Background(), []byte("cpu"), 5, false)
 	values, err := c.ReadFloatBlock(&buf)
 	if err != nil {
 		t.Fatalf("unexpected error reading values: %v", err)
@@ -1209,7 +1210,7 @@ func TestFileStore_SeekToDesc_OverlapMaxInteger(t *testing.T) {
 
 	// Search for an entry that exists in the second file
 	buf := make([]tsm1.IntegerValue, 1000)
-	c := fs.KeyCursor([]byte("cpu"), 5, false)
+	c := fs.KeyCursor(context.Background(), []byte("cpu"), 5, false)
 	values, err := c.ReadIntegerBlock(&buf)
 	if err != nil {
 		t.Fatalf("unexpected error reading values: %v", err)
@@ -1271,7 +1272,7 @@ func TestFileStore_SeekToDesc_OverlapMaxUnsigned(t *testing.T) {
 
 	// Search for an entry that exists in the second file
 	buf := make([]tsm1.UnsignedValue, 1000)
-	c := fs.KeyCursor([]byte("cpu"), 5, false)
+	c := fs.KeyCursor(context.Background(), []byte("cpu"), 5, false)
 	values, err := c.ReadUnsignedBlock(&buf)
 	if err != nil {
 		t.Fatalf("unexpected error reading values: %v", err)
@@ -1334,7 +1335,7 @@ func TestFileStore_SeekToDesc_OverlapMaxBoolean(t *testing.T) {
 
 	// Search for an entry that exists in the second file
 	buf := make([]tsm1.BooleanValue, 1000)
-	c := fs.KeyCursor([]byte("cpu"), 5, false)
+	c := fs.KeyCursor(context.Background(), []byte("cpu"), 5, false)
 	values, err := c.ReadBooleanBlock(&buf)
 	if err != nil {
 		t.Fatalf("unexpected error reading values: %v", err)
@@ -1397,7 +1398,7 @@ func TestFileStore_SeekToDesc_OverlapMaxString(t *testing.T) {
 
 	// Search for an entry that exists in the second file
 	buf := make([]tsm1.StringValue, 1000)
-	c := fs.KeyCursor([]byte("cpu"), 5, false)
+	c := fs.KeyCursor(context.Background(), []byte("cpu"), 5, false)
 	values, err := c.ReadStringBlock(&buf)
 	if err != nil {
 		t.Fatalf("unexpected error reading values: %v", err)
@@ -1458,7 +1459,7 @@ func TestFileStore_SeekToDesc_AfterEnd(t *testing.T) {
 	fs.Replace(nil, files)
 
 	buf := make([]tsm1.FloatValue, 1000)
-	c := fs.KeyCursor([]byte("cpu"), 4, false)
+	c := fs.KeyCursor(context.Background(), []byte("cpu"), 4, false)
 	values, err := c.ReadFloatBlock(&buf)
 	if err != nil {
 		t.Fatalf("unexpected error reading values: %v", err)
@@ -1497,7 +1498,7 @@ func TestFileStore_SeekToDesc_AfterEnd_OverlapFloat(t *testing.T) {
 	fs.Replace(nil, files)
 
 	buf := make([]tsm1.FloatValue, 1000)
-	c := fs.KeyCursor([]byte("cpu"), 10, false)
+	c := fs.KeyCursor(context.Background(), []byte("cpu"), 10, false)
 	values, err := c.ReadFloatBlock(&buf)
 	if err != nil {
 		t.Fatalf("unexpected error reading values: %v", err)
@@ -1594,7 +1595,7 @@ func TestFileStore_SeekToDesc_AfterEnd_OverlapInteger(t *testing.T) {
 	fs.Replace(nil, files)
 
 	buf := make([]tsm1.IntegerValue, 1000)
-	c := fs.KeyCursor([]byte("cpu"), 11, false)
+	c := fs.KeyCursor(context.Background(), []byte("cpu"), 11, false)
 	values, err := c.ReadIntegerBlock(&buf)
 	if err != nil {
 		t.Fatalf("unexpected error reading values: %v", err)
@@ -1671,7 +1672,7 @@ func TestFileStore_SeekToDesc_AfterEnd_OverlapUnsigned(t *testing.T) {
 	fs.Replace(nil, files)
 
 	buf := make([]tsm1.UnsignedValue, 1000)
-	c := fs.KeyCursor([]byte("cpu"), 11, false)
+	c := fs.KeyCursor(context.Background(), []byte("cpu"), 11, false)
 	values, err := c.ReadUnsignedBlock(&buf)
 	if err != nil {
 		t.Fatalf("unexpected error reading values: %v", err)
@@ -1748,7 +1749,7 @@ func TestFileStore_SeekToDesc_AfterEnd_OverlapBoolean(t *testing.T) {
 	fs.Replace(nil, files)
 
 	buf := make([]tsm1.BooleanValue, 1000)
-	c := fs.KeyCursor([]byte("cpu"), 11, false)
+	c := fs.KeyCursor(context.Background(), []byte("cpu"), 11, false)
 	values, err := c.ReadBooleanBlock(&buf)
 	if err != nil {
 		t.Fatalf("unexpected error reading values: %v", err)
@@ -1845,7 +1846,7 @@ func TestFileStore_SeekToDesc_AfterEnd_OverlapString(t *testing.T) {
 	fs.Replace(nil, files)
 
 	buf := make([]tsm1.StringValue, 1000)
-	c := fs.KeyCursor([]byte("cpu"), 11, false)
+	c := fs.KeyCursor(context.Background(), []byte("cpu"), 11, false)
 	values, err := c.ReadStringBlock(&buf)
 	if err != nil {
 		t.Fatalf("unexpected error reading values: %v", err)
@@ -1945,7 +1946,7 @@ func TestFileStore_SeekToDesc_Middle(t *testing.T) {
 
 	// Search for an entry that exists in the second file
 	buf := make([]tsm1.FloatValue, 1000)
-	c := fs.KeyCursor([]byte("cpu"), 3, false)
+	c := fs.KeyCursor(context.Background(), []byte("cpu"), 3, false)
 	values, err := c.ReadFloatBlock(&buf)
 	if err != nil {
 		t.Fatalf("unexpected error reading values: %v", err)
@@ -2018,7 +2019,7 @@ func TestFileStore_SeekToDesc_End(t *testing.T) {
 	fs.Replace(nil, files)
 
 	buf := make([]tsm1.FloatValue, 1000)
-	c := fs.KeyCursor([]byte("cpu"), 2, false)
+	c := fs.KeyCursor(context.Background(), []byte("cpu"), 2, false)
 	values, err := c.ReadFloatBlock(&buf)
 	if err != nil {
 		t.Fatalf("unexpected error reading values: %v", err)
@@ -2060,7 +2061,7 @@ func TestKeyCursor_TombstoneRange(t *testing.T) {
 	}
 
 	buf := make([]tsm1.FloatValue, 1000)
-	c := fs.KeyCursor([]byte("cpu"), 0, true)
+	c := fs.KeyCursor(context.Background(), []byte("cpu"), 0, true)
 	expValues := []int{0, 2}
 	for _, v := range expValues {
 		values, err := c.ReadFloatBlock(&buf)
@@ -2105,7 +2106,7 @@ func TestKeyCursor_TombstoneRange_PartialFloat(t *testing.T) {
 	}
 
 	buf := make([]tsm1.FloatValue, 1000)
-	c := fs.KeyCursor([]byte("cpu"), 0, true)
+	c := fs.KeyCursor(context.Background(), []byte("cpu"), 0, true)
 	values, err := c.ReadFloatBlock(&buf)
 	if err != nil {
 		t.Fatalf("unexpected error reading values: %v", err)
@@ -2149,7 +2150,7 @@ func TestKeyCursor_TombstoneRange_PartialInteger(t *testing.T) {
 	}
 
 	buf := make([]tsm1.IntegerValue, 1000)
-	c := fs.KeyCursor([]byte("cpu"), 0, true)
+	c := fs.KeyCursor(context.Background(), []byte("cpu"), 0, true)
 	values, err := c.ReadIntegerBlock(&buf)
 	if err != nil {
 		t.Fatalf("unexpected error reading values: %v", err)
@@ -2193,7 +2194,7 @@ func TestKeyCursor_TombstoneRange_PartialUnsigned(t *testing.T) {
 	}
 
 	buf := make([]tsm1.UnsignedValue, 1000)
-	c := fs.KeyCursor([]byte("cpu"), 0, true)
+	c := fs.KeyCursor(context.Background(), []byte("cpu"), 0, true)
 	values, err := c.ReadUnsignedBlock(&buf)
 	if err != nil {
 		t.Fatalf("unexpected error reading values: %v", err)
@@ -2237,7 +2238,7 @@ func TestKeyCursor_TombstoneRange_PartialString(t *testing.T) {
 	}
 
 	buf := make([]tsm1.StringValue, 1000)
-	c := fs.KeyCursor([]byte("cpu"), 0, true)
+	c := fs.KeyCursor(context.Background(), []byte("cpu"), 0, true)
 	values, err := c.ReadStringBlock(&buf)
 	if err != nil {
 		t.Fatalf("unexpected error reading values: %v", err)
@@ -2281,7 +2282,7 @@ func TestKeyCursor_TombstoneRange_PartialBoolean(t *testing.T) {
 	}
 
 	buf := make([]tsm1.BooleanValue, 1000)
-	c := fs.KeyCursor([]byte("cpu"), 0, true)
+	c := fs.KeyCursor(context.Background(), []byte("cpu"), 0, true)
 	values, err := c.ReadBooleanBlock(&buf)
 	if err != nil {
 		t.Fatalf("unexpected error reading values: %v", err)
@@ -2403,7 +2404,7 @@ func TestFileStore_Replace(t *testing.T) {
 	}
 
 	// Should record references to the two existing TSM files
-	cur := fs.KeyCursor([]byte("cpu"), 0, true)
+	cur := fs.KeyCursor(context.Background(), []byte("cpu"), 0, true)
 
 	// Should move the existing files out of the way, but allow query to complete
 	if err := fs.Replace(files[:2], []string{replacement}); err != nil {

tsdb/engine/tsm1/iterator.gen.go

@@ -13,6 +13,9 @@ import (
 	"sync"
 
 	"github.com/influxdata/influxdb/influxql"
+	"github.com/influxdata/influxdb/pkg/metrics"
+	"github.com/influxdata/influxdb/pkg/tracing"
+	"github.com/influxdata/influxdb/pkg/tracing/fields"
 	"github.com/influxdata/influxdb/query"
 	"github.com/influxdata/influxdb/tsdb"
 	"github.com/uber-go/zap"
@@ -142,6 +145,36 @@ func (itr *floatFinalizerIterator) Close() error {
 	return itr.FloatIterator.Close()
 }
 
+type floatInstrumentedIterator struct {
+	query.FloatIterator
+	span  *tracing.Span
+	group *metrics.Group
+}
+
+func newFloatInstrumentedIterator(inner query.FloatIterator, span *tracing.Span, group *metrics.Group) *floatInstrumentedIterator {
+	return &floatInstrumentedIterator{FloatIterator: inner, span: span, group: group}
+}
+
+func (itr *floatInstrumentedIterator) Close() error {
+	var f []fields.Field
+	itr.group.ForEach(func(v metrics.Metric) {
+		switch m := v.(type) {
+		case *metrics.Counter:
+			f = append(f, fields.Int64(m.Name(), m.Value()))
+
+		case *metrics.Timer:
+			f = append(f, fields.Duration(m.Name(), m.Value()))
+
+		default:
+			panic("unexpected metrics")
+		}
+	})
+	itr.span.SetFields(fields.New(f...))
+	itr.span.Finish()
+
+	return itr.FloatIterator.Close()
+}
+
 type floatIterator struct {
 	cur   floatCursor
 	aux   []cursorAt
@@ -575,6 +608,36 @@ func (itr *integerFinalizerIterator) Close() error {
 	return itr.IntegerIterator.Close()
 }
 
+type integerInstrumentedIterator struct {
+	query.IntegerIterator
+	span  *tracing.Span
+	group *metrics.Group
+}
+
+func newIntegerInstrumentedIterator(inner query.IntegerIterator, span *tracing.Span, group *metrics.Group) *integerInstrumentedIterator {
+	return &integerInstrumentedIterator{IntegerIterator: inner, span: span, group: group}
+}
+
+func (itr *integerInstrumentedIterator) Close() error {
+	var f []fields.Field
+	itr.group.ForEach(func(v metrics.Metric) {
+		switch m := v.(type) {
+		case *metrics.Counter:
+			f = append(f, fields.Int64(m.Name(), m.Value()))
+
+		case *metrics.Timer:
+			f = append(f, fields.Duration(m.Name(), m.Value()))
+
+		default:
+			panic("unexpected metrics")
+		}
+	})
+	itr.span.SetFields(fields.New(f...))
+	itr.span.Finish()
+
+	return itr.IntegerIterator.Close()
+}
+
 type integerIterator struct {
 	cur   integerCursor
 	aux   []cursorAt
@@ -1008,6 +1071,36 @@ func (itr *unsignedFinalizerIterator) Close() error {
 	return itr.UnsignedIterator.Close()
 }
 
+type unsignedInstrumentedIterator struct {
+	query.UnsignedIterator
+	span  *tracing.Span
+	group *metrics.Group
+}
+
+func newUnsignedInstrumentedIterator(inner query.UnsignedIterator, span *tracing.Span, group *metrics.Group) *unsignedInstrumentedIterator {
+	return &unsignedInstrumentedIterator{UnsignedIterator: inner, span: span, group: group}
+}
+
+func (itr *unsignedInstrumentedIterator) Close() error {
+	var f []fields.Field
+	itr.group.ForEach(func(v metrics.Metric) {
+		switch m := v.(type) {
+		case *metrics.Counter:
+			f = append(f, fields.Int64(m.Name(), m.Value()))
+
+		case *metrics.Timer:
+			f = append(f, fields.Duration(m.Name(), m.Value()))
+
+		default:
+			panic("unexpected metrics")
+		}
+	})
+	itr.span.SetFields(fields.New(f...))
+	itr.span.Finish()
+
+	return itr.UnsignedIterator.Close()
+}
+
 type unsignedIterator struct {
 	cur   unsignedCursor
 	aux   []cursorAt
@@ -1441,6 +1534,36 @@ func (itr *stringFinalizerIterator) Close() error {
 	return itr.StringIterator.Close()
 }
 
+type stringInstrumentedIterator struct {
+	query.StringIterator
+	span  *tracing.Span
+	group *metrics.Group
+}
+
+func newStringInstrumentedIterator(inner query.StringIterator, span *tracing.Span, group *metrics.Group) *stringInstrumentedIterator {
+	return &stringInstrumentedIterator{StringIterator: inner, span: span, group: group}
+}
+
+func (itr *stringInstrumentedIterator) Close() error {
+	var f []fields.Field
+	itr.group.ForEach(func(v metrics.Metric) {
+		switch m := v.(type) {
+		case *metrics.Counter:
+			f = append(f, fields.Int64(m.Name(), m.Value()))
+
+		case *metrics.Timer:
+			f = append(f, fields.Duration(m.Name(), m.Value()))
+
+		default:
+			panic("unexpected metrics")
+		}
+	})
+	itr.span.SetFields(fields.New(f...))
+	itr.span.Finish()
+
+	return itr.StringIterator.Close()
+}
+
 type stringIterator struct {
 	cur   stringCursor
 	aux   []cursorAt
@@ -1874,6 +1997,36 @@ func (itr *booleanFinalizerIterator) Close() error {
 	return itr.BooleanIterator.Close()
 }
 
+type booleanInstrumentedIterator struct {
+	query.BooleanIterator
+	span  *tracing.Span
+	group *metrics.Group
+}
+
+func newBooleanInstrumentedIterator(inner query.BooleanIterator, span *tracing.Span, group *metrics.Group) *booleanInstrumentedIterator {
+	return &booleanInstrumentedIterator{BooleanIterator: inner, span: span, group: group}
+}
+
+func (itr *booleanInstrumentedIterator) Close() error {
+	var f []fields.Field
+	itr.group.ForEach(func(v metrics.Metric) {
+		switch m := v.(type) {
+		case *metrics.Counter:
+			f = append(f, fields.Int64(m.Name(), m.Value()))
+
+		case *metrics.Timer:
+			f = append(f, fields.Duration(m.Name(), m.Value()))
+
+		default:
+			panic("unexpected metrics")
+		}
+	})
+	itr.span.SetFields(fields.New(f...))
+	itr.span.Finish()
+
+	return itr.BooleanIterator.Close()
+}
+
 type booleanIterator struct {
 	cur   booleanCursor
 	aux   []cursorAt

tsdb/engine/tsm1/iterator.gen.go.tmpl

@@ -7,6 +7,9 @@ import (
 	"sync"
 
 	"github.com/influxdata/influxdb/influxql"
+	"github.com/influxdata/influxdb/pkg/metrics"
+	"github.com/influxdata/influxdb/pkg/tracing"
+	"github.com/influxdata/influxdb/pkg/tracing/field"
 	"github.com/influxdata/influxdb/query"
 	"github.com/influxdata/influxdb/tsdb"
 	"github.com/uber-go/zap"
@@ -138,6 +141,38 @@ func (itr *{{.name}}FinalizerIterator) Close() error {
 	return itr.{{.Name}}Iterator.Close()
 }
 
+
+type {{.name}}InstrumentedIterator struct {
+	query.{{.Name}}Iterator
+	span  *tracing.Span
+	group *metrics.Group
+}
+
+func new{{.Name}}InstrumentedIterator(inner query.{{.Name}}Iterator, span *tracing.Span, group *metrics.Group) *{{.name}}InstrumentedIterator {
+	return &{{.name}}InstrumentedIterator{ {{.Name}}Iterator: inner, span: span, group: group}
+}
+
+func (itr *{{.name}}InstrumentedIterator) Close() error {
+	var f []field.Field
+	itr.group.ForEach(func(v metrics.Metric) {
+		switch m := v.(type) {
+		case *metrics.Counter:
+			f = append(f, field.Int64(m.Name(), m.Value()))
+
+		case *metrics.Timer:
+			f = append(f, field.Duration(m.Name(), m.Value()))
+
+		default:
+			panic("unexpected metrics")
+		}
+	})
+	itr.span.SetFieldSet(field.Fields(f...))
+	itr.span.Finish()
+
+	return itr.{{.Name}}Iterator.Close()
+}
+
+
 type {{.name}}Iterator struct {
 	cur   {{.name}}Cursor
 	aux   []cursorAt

tsdb/engine/tsm1/iterator.go

@@ -1,8 +1,11 @@
 package tsm1
 
 import (
+	"context"
 	"fmt"
 
+	"github.com/influxdata/influxdb/pkg/metrics"
+	"github.com/influxdata/influxdb/pkg/tracing"
 	"github.com/influxdata/influxdb/query"
 	"github.com/influxdata/influxdb/tsdb"
 	"github.com/uber-go/zap"
@@ -153,13 +156,13 @@ func (c cursorsAt) close() {
 // newMergeFinalizerIterator creates a new Merge iterator from the inputs. If the call to Merge succeeds,
 // the resulting Iterator will be wrapped in a finalizer iterator.
 // If Merge returns an error, the inputs will be closed.
-func newMergeFinalizerIterator(inputs []query.Iterator, opt query.IteratorOptions, log zap.Logger) (query.Iterator, error) {
+func newMergeFinalizerIterator(ctx context.Context, inputs []query.Iterator, opt query.IteratorOptions, log zap.Logger) (query.Iterator, error) {
 	itr, err := query.Iterators(inputs).Merge(opt)
 	if err != nil {
 		query.Iterators(inputs).Close()
 		return nil, err
 	}
-	return newFinalizerIterator(itr, log), nil
+	return newInstrumentedIterator(ctx, newFinalizerIterator(itr, log)), nil
 }
 
 // newFinalizerIterator creates a new iterator that installs a runtime finalizer
@@ -186,3 +189,30 @@ func newFinalizerIterator(itr query.Iterator, log zap.Logger) query.Iterator {
 		panic(fmt.Sprintf("unsupported finalizer iterator type: %T", itr))
 	}
 }
+
+func newInstrumentedIterator(ctx context.Context, itr query.Iterator) query.Iterator {
+	if itr == nil {
+		return nil
+	}
+
+	span := tracing.SpanFromContext(ctx)
+	grp := metrics.GroupFromContext(ctx)
+	if span == nil || grp == nil {
+		return itr
+	}
+
+	switch inner := itr.(type) {
+	case query.FloatIterator:
+		return newFloatInstrumentedIterator(inner, span, grp)
+	case query.IntegerIterator:
+		return newIntegerInstrumentedIterator(inner, span, grp)
+	case query.UnsignedIterator:
+		return newUnsignedInstrumentedIterator(inner, span, grp)
+	case query.StringIterator:
+		return newStringInstrumentedIterator(inner, span, grp)
+	case query.BooleanIterator:
+		return newBooleanInstrumentedIterator(inner, span, grp)
+	default:
+		panic(fmt.Sprintf("unsupported instrumented iterator type: %T", itr))
+	}
+}

tsdb/shard.go

@@ -2,6 +2,7 @@ package tsdb
 
 import (
 	"bytes"
+	"context"
 	"errors"
 	"fmt"
 	"io"
@@ -817,19 +818,18 @@ func (s *Shard) WriteTo(w io.Writer) (int64, error) {
 }
 
 // CreateIterator returns an iterator for the data in the shard.
-func (s *Shard) CreateIterator(measurement string, opt query.IteratorOptions) (query.Iterator, error) {
+func (s *Shard) CreateIterator(ctx context.Context, measurement string, opt query.IteratorOptions) (query.Iterator, error) {
 	engine, err := s.engine()
 	if err != nil {
 		return nil, err
 	}
-
 	if strings.HasPrefix(measurement, "_") {
 		if itr, ok, err := s.createSystemIterator(engine, measurement, opt); ok {
 			return itr, err
 		}
 		// Unknown system source so pass this to the engine.
 	}
-	return engine.CreateIterator(measurement, opt)
+	return engine.CreateIterator(ctx, measurement, opt)
 }
 
 // createSystemIterator returns an iterator for a field of system source.
@@ -1164,7 +1164,7 @@ type ShardGroup interface {
 	MeasurementsByRegex(re *regexp.Regexp) []string
 	FieldDimensions(measurements []string) (fields map[string]influxql.DataType, dimensions map[string]struct{}, err error)
 	MapType(measurement, field string) influxql.DataType
-	CreateIterator(measurement string, opt query.IteratorOptions) (query.Iterator, error)
+	CreateIterator(ctx context.Context, measurement string, opt query.IteratorOptions) (query.Iterator, error)
 	IteratorCost(measurement string, opt query.IteratorOptions) (query.IteratorCost, error)
 	ExpandSources(sources influxql.Sources) (influxql.Sources, error)
 }
@@ -1245,10 +1245,10 @@ func (a Shards) MapType(measurement, field string) influxql.DataType {
 	return typ
 }
 
-func (a Shards) CreateIterator(measurement string, opt query.IteratorOptions) (query.Iterator, error) {
+func (a Shards) CreateIterator(ctx context.Context, measurement string, opt query.IteratorOptions) (query.Iterator, error) {
 	itrs := make([]query.Iterator, 0, len(a))
 	for _, sh := range a {
-		itr, err := sh.CreateIterator(measurement, opt)
+		itr, err := sh.CreateIterator(ctx, measurement, opt)
 		if err != nil {
 			query.Iterators(itrs).Close()
 			return nil, err

tsdb/shard_test.go

@@ -1,6 +1,7 @@
 package tsdb_test
 
 import (
+	"context"
 	"fmt"
 	"io/ioutil"
 	"os"
@@ -464,7 +465,7 @@ func TestShard_WritePoints_FieldConflictConcurrentQuery(t *testing.T) {
 
 			sh.WritePoints(points)
 
-			iter, err := sh.CreateIterator("cpu", query.IteratorOptions{
+			iter, err := sh.CreateIterator(context.Background(), "cpu", query.IteratorOptions{
 				Expr:       influxql.MustParseExpr(`value`),
 				Aux:        []influxql.VarRef{{Val: "value"}},
 				Dimensions: []string{},
@@ -525,7 +526,7 @@ func TestShard_WritePoints_FieldConflictConcurrentQuery(t *testing.T) {
 
 			sh.WritePoints(points)
 
-			iter, err := sh.CreateIterator("cpu", query.IteratorOptions{
+			iter, err := sh.CreateIterator(context.Background(), "cpu", query.IteratorOptions{
 				Expr:       influxql.MustParseExpr(`value`),
 				Aux:        []influxql.VarRef{{Val: "value"}},
 				Dimensions: []string{},
@@ -609,7 +610,7 @@ func TestShard_CreateIterator_Ascending(t *testing.T) {
 
 		// Calling CreateIterator when the engine is not open will return
 		// ErrEngineClosed.
-		_, got := sh.CreateIterator("cpu", query.IteratorOptions{})
+		_, got := sh.CreateIterator(context.Background(), "cpu", query.IteratorOptions{})
 		if exp := tsdb.ErrEngineClosed; got != exp {
 			t.Fatalf("got %v, expected %v", got, exp)
 		}
@@ -626,7 +627,7 @@ cpu,host=serverB,region=uswest value=25  0
 
 		// Create iterator.
 		var err error
-		itr, err = sh.CreateIterator("cpu", query.IteratorOptions{
+		itr, err = sh.CreateIterator(context.Background(), "cpu", query.IteratorOptions{
 			Expr:       influxql.MustParseExpr(`value`),
 			Aux:        []influxql.VarRef{{Val: "val2"}},
 			Dimensions: []string{"host"},
@@ -694,7 +695,7 @@ func TestShard_CreateIterator_Descending(t *testing.T) {
 
 		// Calling CreateIterator when the engine is not open will return
 		// ErrEngineClosed.
-		_, got := sh.CreateIterator("cpu", query.IteratorOptions{})
+		_, got := sh.CreateIterator(context.Background(), "cpu", query.IteratorOptions{})
 		if exp := tsdb.ErrEngineClosed; got != exp {
 			t.Fatalf("got %v, expected %v", got, exp)
 		}
@@ -711,7 +712,7 @@ cpu,host=serverB,region=uswest value=25  0
 
 		// Create iterator.
 		var err error
-		itr, err = sh.CreateIterator("cpu", query.IteratorOptions{
+		itr, err = sh.CreateIterator(context.Background(), "cpu", query.IteratorOptions{
 			Expr:       influxql.MustParseExpr(`value`),
 			Aux:        []influxql.VarRef{{Val: "val2"}},
 			Dimensions: []string{"host"},
@@ -795,7 +796,7 @@ func TestShard_Disabled_WriteQuery(t *testing.T) {
 			t.Fatalf(err.Error())
 		}
 
-		_, got := sh.CreateIterator("cpu", query.IteratorOptions{})
+		_, got := sh.CreateIterator(context.Background(), "cpu", query.IteratorOptions{})
 		if err == nil {
 			t.Fatalf("expected shard disabled error")
 		}
@@ -810,7 +811,7 @@ func TestShard_Disabled_WriteQuery(t *testing.T) {
 			t.Fatalf("unexpected error: %v", err)
 		}
 
-		if _, err = sh.CreateIterator("cpu", query.IteratorOptions{}); err != nil {
+		if _, err = sh.CreateIterator(context.Background(), "cpu", query.IteratorOptions{}); err != nil {
 			t.Fatalf("unexpected error: %v", got)
 		}
 	}

tsdb/store_test.go

@@ -2,6 +2,7 @@ package tsdb_test
 
 import (
 	"bytes"
+	"context"
 	"fmt"
 	"io/ioutil"
 	"math"
@@ -353,7 +354,7 @@ func TestShards_CreateIterator(t *testing.T) {
 		shards := s.ShardGroup([]uint64{0, 1})
 
 		// Create iterator.
-		itr, err := shards.CreateIterator("cpu", query.IteratorOptions{
+		itr, err := shards.CreateIterator(context.Background(), "cpu", query.IteratorOptions{
 			Expr:       influxql.MustParseExpr(`value`),
 			Dimensions: []string{"host"},
 			Ascending:  true,
@@ -443,7 +444,7 @@ func TestStore_BackupRestoreShard(t *testing.T) {
 		}
 
 		// Read data from
-		itr, err := s0.Shard(100).CreateIterator("cpu", query.IteratorOptions{
+		itr, err := s0.Shard(100).CreateIterator(context.Background(), "cpu", query.IteratorOptions{
 			Expr:      influxql.MustParseExpr(`value`),
 			Ascending: true,
 			StartTime: influxql.MinTime,