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docs(tsm1): TagKeys and TagValues return partial results with non-nil errors

pull/14540/head
jlapacik 2019-07-31 13:10:15 -07:00
parent e7a0068e46
commit 945f16ff4b
1 changed files with 18 additions and 22 deletions
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40
tsdb/tsm1/engine_schema.go
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@ -14,11 +14,20 @@ import (
"github.com/influxdata/influxql"
)
// cancelCheckInterval represents the period at which TagKeys and TagValues
// will check for a canceled context. Specifically after every 64 series
// scanned, the query context will be checked for cancellation, and if canceled,
// the calls will immediately return.
const cancelCheckInterval = 64
// TagValues returns an iterator which enumerates the values for the specific
// tagKey in the given bucket matching the predicate within the
// time range (start, end].
//
// TagValues will always return a StringIterator if there is no error.
//
// If the context is canceled before TagValues has finished processing, a non-nil
// error will be returned along with a partial result of the already scanned values.
func (e *Engine) TagValues(ctx context.Context, orgID, bucketID influxdb.ID, tagKey string, start, end int64, predicate influxql.Expr) (cursors.StringIterator, error) {
encoded := tsdb.EncodeName(orgID, bucketID)
@ -180,9 +189,8 @@ func (e *Engine) tagValuesPredicate(ctx context.Context, orgBucket, tagKeyBytes
)
for i := range keys {
// to keep cache scans fast,
// check context every 64 iteratons.
if i%64 == 0 {
// to keep cache scans fast, check context every 'cancelCheckInterval' iteratons
if i%cancelCheckInterval == 0 {
select {
case <-ctx.Done():
stats = statsFromIters(stats, iters)
@ -214,13 +222,6 @@ func (e *Engine) tagValuesPredicate(ctx context.Context, orgBucket, tagKeyBytes
}
for _, iter := range iters {
// Always check context before performing a tsm file scan
select {
case <-ctx.Done():
stats = statsFromIters(stats, iters)
return cursors.NewStringSliceIteratorWithStats(nil, stats), ctx.Err()
default:
}
if exact, _ := iter.Seek(sfkey); !exact {
continue
@ -256,8 +257,8 @@ func (e *Engine) findCandidateKeys(ctx context.Context, orgBucket []byte, predic
var keys [][]byte
for i := 0; ; i++ {
// to keep series file index scans fast,
// check context every 64 iteratons.
if i%64 == 0 {
// check context every 'cancelCheckInterval' iteratons
if i%cancelCheckInterval == 0 {
select {
case <-ctx.Done():
return keys, ctx.Err()
@ -286,6 +287,9 @@ func (e *Engine) findCandidateKeys(ctx context.Context, orgBucket []byte, predic
// bucket matching the predicate within the time range (start, end].
//
// TagKeys will always return a StringIterator if there is no error.
//
// If the context is canceled before TagKeys has finished processing, a non-nil
// error will be returned along with a partial result of the already scanned keys.
func (e *Engine) TagKeys(ctx context.Context, orgID, bucketID influxdb.ID, start, end int64, predicate influxql.Expr) (cursors.StringIterator, error) {
encoded := tsdb.EncodeName(orgID, bucketID)
@ -432,9 +436,8 @@ func (e *Engine) tagKeysPredicate(ctx context.Context, orgBucket []byte, start,
)
for i := range keys {
// to keep cache scans fast,
// check context every 64 iteratons.
if i%64 == 0 {
// to keep cache scans fast, check context every 'cancelCheckInterval' iteratons
if i%cancelCheckInterval == 0 {
select {
case <-ctx.Done():
stats = statsFromIters(stats, iters)
@ -461,13 +464,6 @@ func (e *Engine) tagKeysPredicate(ctx context.Context, orgBucket []byte, start,
}
for _, iter := range iters {
// Always check context before performing a tsm file scan
select {
case <-ctx.Done():
stats = statsFromIters(stats, iters)
return cursors.NewStringSliceIteratorWithStats(nil, stats), ctx.Err()
default:
}
if exact, _ := iter.Seek(sfkey); !exact {
continue