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Fix EPQ crash from missing partition directory in EState

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EvalPlanQualStart() failed to propagate es_partition_directory into
the child EState used for EPQ rechecks. When execution time partition
pruning ran during the EPQ scan, executor code dereferenced a NULL
partition directory and crashed.

Previously, propagating es_partition_directory into the EPQ EState was
unnecessary because CreatePartitionPruneState(), which sets it on
demand, also initialized the exec-pruning context.  After commit
d47cbf474, CreatePartitionPruneState() now initializes only the init-
time pruning context, leaving exec-pruning context initialization to
ExecInitNode(). Since EvalPlanQualStart() runs only ExecInitNode() and
not CreatePartitionPruneState(), it can encounter a NULL
es_partition_directory.  Other executor fields initialized during
CreatePartitionPruneState() are already copied into the child EState
thanks to commit 8741e48e5d, but es_partition_directory was missed.

Fix by borrowing the parent estate's  es_partition_directory in
EvalPlanQualStart(), and by clearing that field in EvalPlanQualEnd()
so the parent remains responsible for freeing the directory.

Add an isolation test permutation that triggers EPQ with execution-
time partition pruning, the case that reproduces this crash.

Bug: #19078
Reported-by: Yuri Zamyatin <yuri@yrz.am>
Diagnosed-by: David Rowley <dgrowleyml@gmail.com>
Author: David Rowley <dgrowleyml@gmail.com>
Co-authored-by: Amit Langote <amitlangote09@gmail.com>
Discussion: https://postgr.es/m/19078-dfd62f840a2c0766@postgresql.org
Backpatch-through: 18
This commit is contained in:
Amit Langote
2025-10-16 14:01:44 +09:00
parent 02c171f63f
commit 905e932f09
3 changed files with 19 additions and 0 deletions
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10
src/backend/executor/execMain.c
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@@ -3093,6 +3093,9 @@ EvalPlanQualStart(EPQState *epqstate, Plan *planTree)
rcestate->es_part_prune_states = parentestate->es_part_prune_states;
rcestate->es_part_prune_results = parentestate->es_part_prune_results;
/* We'll also borrow the es_partition_directory from the parent state */
rcestate->es_partition_directory = parentestate->es_partition_directory;
/*
* Initialize private state information for each SubPlan. We must do this
* before running ExecInitNode on the main query tree, since
@@ -3210,6 +3213,13 @@ EvalPlanQualEnd(EPQState *epqstate)
MemoryContextSwitchTo(oldcontext);
/*
* NULLify the partition directory before freeing the executor state.
* Since EvalPlanQualStart() just borrowed the parent EState's directory,
* we'd better leave it up to the parent to delete it.
*/
estate->es_partition_directory = NULL;
FreeExecutorState(estate);
/* Mark EPQState idle */