add node id to execution options

This commit changes the `ExecutionOptions` and `SelectOptions` to
allow a `NodeID` for specifying an exact node to query against.

CHANGELOG.md

@@ -23,6 +23,7 @@
 - [#6713](https://github.com/influxdata/influxdb/pull/6713): Reduce allocations during query parsing.
 - [#3733](https://github.com/influxdata/influxdb/issues/3733): Modify the default retention policy name and make it configurable.
 - [#5655](https://github.com/influxdata/influxdb/issues/5655): Support specifying a retention policy for the graphite service.
+- [#6820](https://github.com/influxdata/influxdb/issues/6820): Add NodeID to execution options
 
 ### Bugfixes
 

coordinator/statement_executor.go

@@ -415,7 +415,10 @@ func (e *StatementExecutor) executeSelectStatement(stmt *influxql.SelectStatemen
 
 	// It is important to "stamp" this time so that everywhere we evaluate `now()` in the statement is EXACTLY the same `now`
 	now := time.Now().UTC()
-	opt := influxql.SelectOptions{InterruptCh: ctx.InterruptCh}
+	opt := influxql.SelectOptions{
+		InterruptCh: ctx.InterruptCh,
+		NodeID:      ctx.ExecutionOptions.NodeID,
+	}
 
 	// Replace instances of "now()" with the current time, and check the resultant times.
 	nowValuer := influxql.NowValuer{Now: now}
@@ -604,7 +607,7 @@ func (e *StatementExecutor) iteratorCreator(stmt *influxql.SelectStatement, opt
 	if err != nil {
 		return nil, err
 	}
-	return e.TSDBStore.IteratorCreator(shards)
+	return e.TSDBStore.IteratorCreator(shards, opt)
 }
 
 func (e *StatementExecutor) executeShowTagValues(stmt *influxql.SelectStatement, ctx *influxql.ExecutionContext, store LocalTSDBStore) error {
@@ -1142,19 +1145,19 @@ type TSDBStore interface {
 	DeleteRetentionPolicy(database, name string) error
 	DeleteSeries(database string, sources []influxql.Source, condition influxql.Expr) error
 	DeleteShard(id uint64) error
-	IteratorCreator(shards []meta.ShardInfo) (influxql.IteratorCreator, error)
+	IteratorCreator(shards []meta.ShardInfo, opt *influxql.SelectOptions) (influxql.IteratorCreator, error)
 }
 
 type LocalTSDBStore struct {
 	*tsdb.Store
 }
 
-func (s LocalTSDBStore) IteratorCreator(shards []meta.ShardInfo) (influxql.IteratorCreator, error) {
+func (s LocalTSDBStore) IteratorCreator(shards []meta.ShardInfo, opt *influxql.SelectOptions) (influxql.IteratorCreator, error) {
 	shardIDs := make([]uint64, len(shards))
 	for i, sh := range shards {
 		shardIDs[i] = sh.ID
 	}
-	return s.Store.IteratorCreator(shardIDs)
+	return s.Store.IteratorCreator(shardIDs, opt)
 }
 
 // ShardIteratorCreator is an interface for creating an IteratorCreator to access a specific shard.

coordinator/statement_executor_test.go

@@ -247,7 +247,7 @@ func (s *TSDBStore) DeleteSeries(database string, sources []influxql.Source, con
 	return s.DeleteSeriesFn(database, sources, condition)
 }
 
-func (s *TSDBStore) IteratorCreator(shards []meta.ShardInfo) (influxql.IteratorCreator, error) {
+func (s *TSDBStore) IteratorCreator(shards []meta.ShardInfo, opt *influxql.SelectOptions) (influxql.IteratorCreator, error) {
 	// Generate iterators for each node.
 	ics := make([]influxql.IteratorCreator, 0)
 	if err := func() error {

influxql/query_executor.go

@@ -70,6 +70,9 @@ type ExecutionOptions struct {
 
 	// If this query is being executed in a read-only context.
 	ReadOnly bool
+
+	// Node to execute on.
+	NodeID uint64
 }
 
 // ExecutionContext contains state that the query is currently executing with.

influxql/select.go

@@ -15,6 +15,10 @@ type SelectOptions struct {
 	// The upper bound for a select call.
 	MaxTime time.Time
 
+	// Node to exclusively read from.
+	// If zero, all nodes are used.
+	NodeID uint64
+
 	// An optional channel that, if closed, signals that the select should be
 	// interrupted.
 	InterruptCh <-chan struct{}

services/httpd/handler.go

@@ -267,6 +267,7 @@ func (h *Handler) serveQuery(w http.ResponseWriter, r *http.Request, user *meta.
 	}(time.Now())
 
 	pretty := r.FormValue("pretty") == "true"
+	nodeID, _ := strconv.ParseUint(r.FormValue("node_id"), 10, 64)
 
 	qp := strings.TrimSpace(r.FormValue("q"))
 	if qp == "" {
@@ -370,6 +371,7 @@ func (h *Handler) serveQuery(w http.ResponseWriter, r *http.Request, user *meta.
 		Database:  db,
 		ChunkSize: chunkSize,
 		ReadOnly:  r.Method == "GET",
+		NodeID:    nodeID,
 	}, closing)
 
 	// if we're not chunking, this will be the in memory buffer for all results before sending to client

tsdb/store.go

@@ -709,7 +709,7 @@ func (s *Store) IteratorCreators() influxql.IteratorCreators {
 	return a
 }
 
-func (s *Store) IteratorCreator(shards []uint64) (influxql.IteratorCreator, error) {
+func (s *Store) IteratorCreator(shards []uint64, opt *influxql.SelectOptions) (influxql.IteratorCreator, error) {
 	// Generate iterators for each node.
 	ics := make([]influxql.IteratorCreator, 0)
 	if err := func() error {