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Merge pull request #9056 from prometheus/beorn7/histogram2

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Fix re-encoding
This commit is contained in:
Björn Rabenstein 2021-07-06 01:12:16 +02:00 committed by GitHub
commit 08258cc539
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1 changed files with 18 additions and 8 deletions
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26
tsdb/chunkenc/histo.go
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@ -361,10 +361,14 @@ func (a *HistoAppender) AppendHistogram(t int64, h histogram.SparseHistogram) {
} }
// Recode converts the current chunk to accommodate an expansion of the set of // Recode converts the current chunk to accommodate an expansion of the set of
// (positive and/or negative) buckets used, according to the provided interjections, resulting in // (positive and/or negative) buckets used, according to the provided
// the honoring of the provided new posSpans and negSpans // interjections, resulting in the honoring of the provided new posSpans and
// note: the decode-recode can probably be done more efficiently, but that's for a future optimization // negSpans.
func (a *HistoAppender) Recode(posInterjections, negInterjections []Interjection, posSpans, negSpans []histogram.Span) (Chunk, Appender) { func (a *HistoAppender) Recode(posInterjections, negInterjections []Interjection, posSpans, negSpans []histogram.Span) (Chunk, Appender) {
// TODO(beorn7): This currently just decodes everything and then encodes
// it again with the new span layout. This can probably be done in-place
// by editing the chunk. But let's first see how expensive it is in the
// big picture.
it := newHistoIterator(a.b.bytes()) it := newHistoIterator(a.b.bytes())
hc := NewHistoChunk() hc := NewHistoChunk()
app, err := hc.Appender() app, err := hc.Appender()
@ -372,18 +376,24 @@ func (a *HistoAppender) Recode(posInterjections, negInterjections []Interjection
panic(err) panic(err)
} }
numPosBuckets, numNegBuckets := countSpans(posSpans), countSpans(negSpans) numPosBuckets, numNegBuckets := countSpans(posSpans), countSpans(negSpans)
posbuckets := make([]int64, numPosBuckets) // new (modified) histogram buckets
negbuckets := make([]int64, numNegBuckets) // new (modified) histogram buckets
for it.Next() { for it.Next() {
tOld, hOld := it.AtHistogram() tOld, hOld := it.AtHistogram()
// save the modified histogram to the new chunk
// We have to newly allocate slices for the modified buckets
// here because they are kept by the appender until the next
// append.
// TODO(beorn7): We might be able to optimize this.
posBuckets := make([]int64, numPosBuckets)
negBuckets := make([]int64, numNegBuckets)
// Save the modified histogram to the new chunk.
hOld.PositiveSpans, hOld.NegativeSpans = posSpans, negSpans hOld.PositiveSpans, hOld.NegativeSpans = posSpans, negSpans
if len(posInterjections) > 0 { if len(posInterjections) > 0 {
hOld.PositiveBuckets = interject(hOld.PositiveBuckets, posbuckets, posInterjections) hOld.PositiveBuckets = interject(hOld.PositiveBuckets, posBuckets, posInterjections)
} }
if len(negInterjections) > 0 { if len(negInterjections) > 0 {
hOld.NegativeBuckets = interject(hOld.NegativeBuckets, negbuckets, negInterjections) hOld.NegativeBuckets = interject(hOld.NegativeBuckets, negBuckets, negInterjections)
} }
app.AppendHistogram(tOld, hOld) app.AppendHistogram(tOld, hOld)
} }