query-tee: fix behaviour of -proxy.compare-skip-recent-samples for long-running queries
#9416
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jhesketh
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Sep 26, 2024
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What this PR does
This PR fixes an issue in the behaviour of the
-proxy.compare-skip-recent-samplesCLI flag in query-tee.Previously, when deciding whether to skip a sample, sample timestamps were compared to the time at the time the comparison was occurring. However, for a slow query, this may be well after the query was evaluated, and so may mean that
-proxy.compare-skip-recent-samplesis ineffective.This PR changes the behaviour of query-tee to compare sample timestamps to the time at which the query request was sent. This reduces the number of unwanted comparison failures for recent data.
For example, let's say query-tee receives a query at 12:00, the query takes 3 minutes to evaluate through both backends, and
-proxy.compare-skip-recent-samplesis set to 5 minutes. Let's assume everything else happens instantly, so result comparison happens at 12:03.With the old behaviour, samples with timestamps after 11:58 will be considered too recent to compare and skipped.
With the new behaviour in this PR, samples with timestamps after 11:55 will be considered too recent to compare and skipped.
Which issue(s) this PR fixes or relates to
(none)
Checklist
CHANGELOG.mdupdated - the order of entries should be[CHANGE],[FEATURE],[ENHANCEMENT],[BUGFIX].about-versioning.mdupdated with experimental features.