compact/downsample: support native histogram custom buckets downsampling#8706
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Br1an67 wants to merge 3 commits intothanos-io:mainfrom
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compact/downsample: support native histogram custom buckets downsampling#8706Br1an67 wants to merge 3 commits intothanos-io:mainfrom
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Custom bucket histograms (schema < 0) cannot be reduced in resolution using CopyToSchema. Skip schema reduction for custom buckets and use them as-is during downsampling to prevent panic. Signed-off-by: root <root@C20251020184286.local> Signed-off-by: Br1an67 <932039080@qq.com>
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Custom bucket histograms (schema < 0) cannot be subtracted using the Sub operation. When downsampling custom bucket histograms, treat them like counter resets and add the full value to the counter instead of computing a delta. This prevents panics when processing custom bucket histograms during downsampling. Fixes panic in histogramAggregator.add() when trying to subtract custom bucket histograms. Signed-off-by: Br1an67 <932039080@qq.com>
When downsampling histograms, if the schema type changes between custom bucket histograms (schema < 0) and exponential bucket histograms (schema >= 0), the Add operation would fail because these histogram types cannot be added together. This fix checks for incompatible schemas before attempting to add histograms. When incompatible schemas are detected, the aggregation is reset to the new histogram, similar to how counter resets are handled. Fixes panic when mixing custom bucket and exponential bucket histograms during downsampling. Signed-off-by: Br1an67 <932039080@qq.com>
GiedriusS
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What's the difference between https://github.com/thanos-io/thanos/pull/8699/changes and this? Maybe you could collaborate? Could you add a test case?
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Fixes #8698
Changes
minSchemafunction to skip custom bucket schemas (schema < 0) when finding the minimum schema for downsampling. Custom bucket histograms cannot be reduced in resolution usingCopyToSchema.histogramAggregator.addmethod to skip the schema reduction step for custom bucket histograms (schema < 0), allowing them to be used as-is during downsampling.Verification
The fix addresses the panic
cannot reduce resolution to custom buckets schemathat occurred when the compactor tried to downsample native histograms with custom buckets. The changes ensure that:CopyToSchemacall is skipped since it doesn't support custom bucket schemas