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Fix re-encoding 

Signed-off-by: beorn7 <beorn@grafana.com>
pull/9056/head
beorn7 2021-07-06 00:20:35 +02:00
parent 01957eee2b
commit cb75747bce
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
// (positive and/or negative) buckets used, according to the provided interjections, resulting in
// the honoring of the provided new posSpans and negSpans
// note: the decode-recode can probably be done more efficiently, but that's for a future optimization
// (positive and/or negative) buckets used, according to the provided
// interjections, resulting in the honoring of the provided new posSpans and
// negSpans.
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())
hc := NewHistoChunk()
app, err := hc.Appender()
@ -372,18 +376,24 @@ func (a *HistoAppender) Recode(posInterjections, negInterjections []Interjection
panic(err)
}
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() {
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
if len(posInterjections) > 0 {
hOld.PositiveBuckets = interject(hOld.PositiveBuckets, posbuckets, posInterjections)
hOld.PositiveBuckets = interject(hOld.PositiveBuckets, posBuckets, posInterjections)
}
if len(negInterjections) > 0 {
hOld.NegativeBuckets = interject(hOld.NegativeBuckets, negbuckets, negInterjections)
hOld.NegativeBuckets = interject(hOld.NegativeBuckets, negBuckets, negInterjections)
}
app.AppendHistogram(tOld, hOld)
}