sql, sqlstats: remove logical plan sampling cluster settings #138042
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For SQL stats we trace every new fingerprint in an application container in order to populate statistics that are only available via tracing for each fingerprint. This sampling logic worked by tracking the SQL fingerprint strings encountered by each application but did not factor in fingerprints that are not tracked by SQL stats, such as TCL statements (BEGIN, COMMIT, ROLLBACK), were being treated as new fingerprints on each execution which resulted in tracing being turned on. This commit ensures that we don't consider TCL statements in this sampling strategy. TestSampledStatsCollectionOnNewFingerprint is also fixed as it was previously assuming that previously seen statements in new transactions would trigger this sampling behaviour when it should not - this was being erronneously triggered by `BEGIN`. ``` name old time/op new time/op delta Sysbench/SQL/3node/oltp_read_write-10 5.61ms ± 3% 5.69ms ± 4% ~ (p=0.167 n=8+9) name old alloc/op new alloc/op delta Sysbench/SQL/3node/oltp_read_write-10 2.15MB ± 2% 2.12MB ± 2% -1.24% (p=0.029 n=10+10) name old allocs/op new allocs/op delta Sysbench/SQL/3node/oltp_read_write-10 10.7k ± 1% 10.5k ± 0% -1.69% (p=0.000 n=10+9) ``` Epic: none Part of: cockroachdb#133307 Release note: None
We've disabled logical plan sampling via the cluster setting `sql.metrics.statement_details.plan_collection.enabled` since 22.2 since we've been able to collect and deserialize plan gists. We have not heard any issues surrounding disabling this by default so this commit removes logical plan sampling from sql stats entirely. Details: - removes `sql.metrics.statement_details.plan_collection.enabled` which has been false since 22.2. - removes `sql.metrics.statement_details.plan_collection.period` which controlled the time in between samples - removes the `savePlanForStats` field from instrumentationHelper which was a flag used to indicate we should save the logical plan for sql stats Epic: CRDB-45771 Release note (ops change): The following cluster settings have been deprecated: - `sql.metrics.statement_details.plan_collection.enabled` - `sql.metrics.statement_details.plan_collection.period`
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rafiss
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Dec 30, 2024
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drive-by comment: the settings should be added to the retiredSettings map:
cockroach/pkg/settings/registry.go
Line 92 in 356eea0
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We've disabled logical plan sampling via the cluster setting
sql.metrics.statement_details.plan_collection.enabledsince 22.2since we've been able to collect and deserialize plan gists. We
have not heard any issues surrounding disabling this by default so
this commit removes logical plan sampling from sql stats entirely.
Details:
sql.metrics.statement_details.plan_collection.enabledwhich has been false since 22.2.
sql.metrics.statement_details.plan_collection.periodwhichcontrolled the time in between samples
savePlanForStatsfield from instrumentationHelper whichwas a flag used to indicate we should save the logical plan for sql stats
Epic: CRDB-45771
Release note (ops change): The following cluster settings have been
deprecated:
sql.metrics.statement_details.plan_collection.enabledsql.metrics.statement_details.plan_collection.period