Don't create a new DoubleHistogram instance for empty buckets.
#92547
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Currently, the `percentile` and `percentile_ranks` aggregations create a new `DoubleHistogram` instance each time when creating empty aggregation. This is very wasteful. Especially when `numberOfSignificantValueDigits` is `5`. Then each instance costs ~5MB. This change uses `null` instead. At reduce time `InternalHDRPercentileRanks` with a `null` state are skipped. In case all `InternalHDRPercentileRanks` are null then reduce uses an empty `DoubleHistogram` instance. Note that `buildEmptyAggregations()` could also return an empty `DoubleHistogram` instance. However, serializing an empty `DoubleHistogram` instance also adds significant overhead. (`ByteBuffer` instance is created based on `DoubleHistogram#getNeededByteBufferCapacity()`, and that can cause a very large ByteBuffer instance to be created)
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Hi @martijnvg, I've created a changelog YAML for you. |
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Pinging @elastic/es-analytics-geo (Team:Analytics) |
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HiDAl
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Jan 11, 2023
…stic#92547) Currently, the `percentile` and `percentile_ranks` aggregations create a new `DoubleHistogram` instance each time when creating empty aggregation. This is very wasteful. Especially when `numberOfSignificantValueDigits` is `5`. Then each instance costs ~5MB. This change uses `null` instead. At reduce time `InternalHDRPercentileRanks` with a `null` state are skipped. In case all `InternalHDRPercentileRanks` are null then reduce uses an empty `DoubleHistogram` instance. Note that `buildEmptyAggregations()` could also return an empty `DoubleHistogram` instance. However, serializing an empty `DoubleHistogram` instance also adds significant overhead. (`ByteBuffer` instance is created based on `DoubleHistogram#getNeededByteBufferCapacity()`, and that can cause a very large ByteBuffer instance to be created)
danielmitterdorfer
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Jan 12, 2023
…stic#92547) Currently, the `percentile` and `percentile_ranks` aggregations create a new `DoubleHistogram` instance each time when creating empty aggregation. This is very wasteful. Especially when `numberOfSignificantValueDigits` is `5`. Then each instance costs ~5MB. This change uses `null` instead. At reduce time `InternalHDRPercentileRanks` with a `null` state are skipped. In case all `InternalHDRPercentileRanks` are null then reduce uses an empty `DoubleHistogram` instance. Note that `buildEmptyAggregations()` could also return an empty `DoubleHistogram` instance. However, serializing an empty `DoubleHistogram` instance also adds significant overhead. (`ByteBuffer` instance is created based on `DoubleHistogram#getNeededByteBufferCapacity()`, and that can cause a very large ByteBuffer instance to be created)
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Currently, the
percentileandpercentile_ranksaggregations create a newDoubleHistograminstance each time when creating empty aggregation. This is very wasteful. Especially whennumberOfSignificantValueDigitsis5. Then each instance costs ~5MB.This change uses
nullinstead. At reduce timeInternalHDRPercentileRankswith anullstate are skipped. In case allInternalHDRPercentileRanksare null then reduce uses an emptyDoubleHistograminstance.Note that
buildEmptyAggregations()could also return an emptyDoubleHistograminstance. However, serializing an emptyDoubleHistograminstance also adds significant overhead. (ByteBufferinstance is created based onDoubleHistogram#getNeededByteBufferCapacity(), and that can cause a very large ByteBuffer instance to be created)