configurable rejection window for > warn-result-size queries#807
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neil-harkins-sf wants to merge 1 commit intoslack-19.0from
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configurable rejection window for > warn-result-size queries#807neil-harkins-sf wants to merge 1 commit intoslack-19.0from
neil-harkins-sf wants to merge 1 commit intoslack-19.0from
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When vttablet's --queryserver-config-warn-result-size threshold is exceeded, the existing behavior logs a warning but takes no preventive action. This allows repeated large-result queries to compound memory pressure (e.g. heap ballooning to >5GB from queries returning 200k rows). This change adds --queryserver-config-warn-result-size-reject-time-seconds which, when set to a nonzero value, causes vttablet to temporarily block subsequent executions of the same query fingerprint after it triggers the warn threshold. Blocked queries receive FAILED_PRECONDITION, which vtgate will retry on a different tablet (spreading load) or return to the client if all tablets have the fingerprint blocked. Implementation uses a sync.Map in QueryEngine keyed by normalized query template with unix-second expiry, avoiding plan cache invalidation. The setting is dynamically adjustable via /debug/env. Co-Authored-By: Claude <svc-devxp-claude@slack-corp.com>
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Description
When vttablet's --queryserver-config-warn-result-size threshold is exceeded, the existing behavior logs a warning but takes no preventive action. This allows repeated large-result queries to compound memory pressure (e.g. heap ballooning to >5GB from queries returning 200k rows).
This change adds --queryserver-config-warn-result-size-reject-time-seconds which, when set to a nonzero value, causes vttablet to temporarily block subsequent executions of the same query fingerprint after it triggers the warn threshold. Blocked queries receive FAILED_PRECONDITION, which vtgate will retry on a different tablet (spreading load) or return to the client if all tablets have the fingerprint blocked.
Implementation uses a sync.Map in QueryEngine keyed by normalized query template with unix-second expiry, avoiding plan cache invalidation. The setting is dynamically adjustable via /debug/env.
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AI Disclosure
This PR was written by Claude Code unde rmy guidance.