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Amit Langote 525392d572 Don't lock partitions pruned by initial pruning ... Before executing a cached generic plan, AcquireExecutorLocks() in plancache.c locks all relations in a plan's range table to ensure the plan is safe for execution. However, this locks runtime-prunable relations that will later be pruned during "initial" runtime pruning, introducing unnecessary overhead. This commit defers locking for such relations to executor startup and ensures that if the CachedPlan is invalidated due to concurrent DDL during this window, replanning is triggered. Deferring these locks avoids unnecessary locking overhead for pruned partitions, resulting in significant speedup, particularly when many partitions are pruned during initial runtime pruning. * Changes to locking when executing generic plans: AcquireExecutorLocks() now locks only unprunable relations, that is, those found in PlannedStmt.unprunableRelids (introduced in commit cbc127917e), to avoid locking runtime-prunable partitions unnecessarily. The remaining locks are taken by ExecDoInitialPruning(), which acquires them only for partitions that survive pruning. This deferral does not affect the locks required for permission checking in InitPlan(), which takes place before initial pruning. ExecCheckPermissions() now includes an Assert to verify that all relations undergoing permission checks, none of which can be in the set of runtime-prunable relations, are properly locked. * Plan invalidation handling: Deferring locks introduces a window where prunable relations may be altered by concurrent DDL, invalidating the plan. A new function, ExecutorStartCachedPlan(), wraps ExecutorStart() to detect and handle invalidation caused by deferred locking. If invalidation occurs, ExecutorStartCachedPlan() updates CachedPlan using the new UpdateCachedPlan() function and retries execution with the updated plan. To ensure all code paths that may be affected by this handle invalidation properly, all callers of ExecutorStart that may execute a PlannedStmt from a CachedPlan have been updated to use ExecutorStartCachedPlan() instead. UpdateCachedPlan() replaces stale plans in CachedPlan.stmt_list. A new CachedPlan.stmt_context, created as a child of CachedPlan.context, allows freeing old PlannedStmts while preserving the CachedPlan structure and its statement list. This ensures that loops over statements in upstream callers of ExecutorStartCachedPlan() remain intact. ExecutorStart() and ExecutorStart_hook implementations now return a boolean value indicating whether plan initialization succeeded with a valid PlanState tree in QueryDesc.planstate, or false otherwise, in which case QueryDesc.planstate is NULL. Hook implementations are required to call standard_ExecutorStart() at the beginning, and if it returns false, they should do the same without proceeding. * Testing: To verify these changes, the delay_execution module tests scenarios where cached plans become invalid due to changes in prunable relations after deferred locks. * Note to extension authors: ExecutorStart_hook implementations must verify plan validity after calling standard_ExecutorStart(), as explained earlier. For example: if (prev_ExecutorStart) plan_valid = prev_ExecutorStart(queryDesc, eflags); else plan_valid = standard_ExecutorStart(queryDesc, eflags); if (!plan_valid) return false; <extension-code> return true; Extensions accessing child relations, especially prunable partitions, via ExecGetRangeTableRelation() must now ensure their RT indexes are present in es_unpruned_relids (introduced in commit cbc127917e), or they will encounter an error. This is a strict requirement after this change, as only relations in that set are locked. The idea of deferring some locks to executor startup, allowing locks for prunable partitions to be skipped, was first proposed by Tom Lane. Reviewed-by: Robert Haas <robertmhaas@gmail.com> (earlier versions) Reviewed-by: David Rowley <dgrowleyml@gmail.com> (earlier versions) Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us> (earlier versions) Reviewed-by: Tomas Vondra <tomas@vondra.me> Reviewed-by: Junwang Zhao <zhjwpku@gmail.com> Discussion: https://postgr.es/m/CA+HiwqFGkMSge6TgC9KQzde0ohpAycLQuV7ooitEEpbKB0O_mg@mail.gmail.com		10 months ago
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t	Update copyright for 2025	12 months ago
.gitignore	…
Makefile	…
auto_explain.c	Don't lock partitions pruned by initial pruning	10 months ago
meson.build	Update copyright for 2025	12 months ago