fix(engine): align range-query evaluation timestamps to the step grid - #20904
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Range queries (step > 0) must evaluate at timestamps that are multiples of `step` relative to the Unix epoch, matching Prometheus's standard behaviour. The fix floors `startTs` to the nearest epoch-aligned step boundary before building the windows array, and propagates the aligned value back into `opts.startTs` so that the matcher factory's index arithmetic stays in sync with the windows.
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I think this logic should be in the logical planner |
DylanGuedes
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What this PR does / why we need it:
On this PR I'm aligning
startTsto the nearest epoch-aligned step boundary, to replicate the same behavior we'd have with the old engine. I found this to cause asum by(x)(count_over_time({k="v"}[30m))query to mismatch old vs the new engine.Which issue(s) this PR fixes:
Fixes #
Special notes for your reviewer:
Checklist
CONTRIBUTING.mdguide (required)featPRs are unlikely to be accepted unless a case can be made for the feature actually being a bug fix to existing behavior.docs/sources/setup/upgrade/_index.mddeprecated-config.yamlanddeleted-config.yamlfiles respectively in thetools/deprecated-config-checkerdirectory. Example PR