Fix EPQ crash from missing partition pruning state in EState

Commit bb3ec16e14 moved partition pruning metadata into PlannedStmt.
At executor startup this metadata is used to initialize the EState
fields es_part_prune_infos, es_part_prune_states, and
es_part_prune_results.  EvalPlanQualStart() failed to copy those
fields into the child EState, causing NULL dereference when Append
ran partition pruning during a recheck. This can occur with DELETE
or UPDATE on partitioned tables that use runtime pruning, e.g. with
generic plans.

Fix by copying all partition pruning state into the EPQ estate.

Add an isolation test that reproduces the crash with concurrent
UPDATE and DELETE on a partitioned table, where the DELETE session
hits the crash during its EPQ recheck after the UPDATE commits.

Bug: #19056
Reported-by: Fei Changhong <feichanghong@qq.com>
Diagnozed-by: Fei Changhong <feichanghong@qq.com>
Author: David Rowley <dgrowleyml@gmail.com>
Co-authored-by: Amit Langote <amitlangote09@gmail.com>
Discussion: https://postgr.es/m/19056-a677cef9b54d76a0%40postgresql.org

3 files changed, 26 insertions, 0 deletions

diff --git a/src/backend/executor/execMain.c b/src/backend/executor/execMain.c
index ff12e2e1364..831c55ce787 100644
--- a/src/backend/executor/execMain.c
+++ b/src/backend/executor/execMain.c
@@ -3085,6 +3085,15 @@ EvalPlanQualStart(EPQState *epqstate, Plan *planTree)
 	rcestate->es_unpruned_relids = parentestate->es_unpruned_relids;
 
 	/*
+	 * Also make the PartitionPruneInfo and the results of pruning available.
+	 * These need to match exactly so that we initialize all the same Append
+	 * and MergeAppend subplans as the parent did.
+	 */
+	rcestate->es_part_prune_infos = parentestate->es_part_prune_infos;
+	rcestate->es_part_prune_states = parentestate->es_part_prune_states;
+	rcestate->es_part_prune_results = parentestate->es_part_prune_results;
+
+	/*
 	 * Initialize private state information for each SubPlan.  We must do this
 	 * before running ExecInitNode on the main query tree, since
 	 * ExecInitSubPlan expects to be able to find these entries. Some of the
diff --git a/src/test/isolation/expected/eval-plan-qual.out b/src/test/isolation/expected/eval-plan-qual.out
index 3d31d0f84e5..60eca44b4e3 100644
--- a/src/test/isolation/expected/eval-plan-qual.out
+++ b/src/test/isolation/expected/eval-plan-qual.out
@@ -1457,3 +1457,12 @@ step sysmerge2:
 step c1: COMMIT;
 step sysmerge2: <... completed>
 step c2: COMMIT;
+
+starting permutation: s1pp1 s2pp1 s2pp2 s2pp3 c1 c2
+step s1pp1: UPDATE another_parttbl SET b = b + 1 WHERE a = 1;
+step s2pp1: SET plan_cache_mode TO force_generic_plan;
+step s2pp2: PREPARE epd AS DELETE FROM another_parttbl WHERE a = $1;
+step s2pp3: EXECUTE epd(1); <waiting ...>
+step c1: COMMIT;
+step s2pp3: <... completed>
+step c2: COMMIT;
diff --git a/src/test/isolation/specs/eval-plan-qual.spec b/src/test/isolation/specs/eval-plan-qual.spec
index c6eee685586..64afffb1d83 100644
--- a/src/test/isolation/specs/eval-plan-qual.spec
+++ b/src/test/isolation/specs/eval-plan-qual.spec
@@ -204,6 +204,7 @@ step sys1	{
 	UPDATE pg_class SET reltuples = 123 WHERE oid = 'accounts'::regclass;
 }
 
+step s1pp1 { UPDATE another_parttbl SET b = b + 1 WHERE a = 1; }
 
 session s2
 setup		{ BEGIN ISOLATION LEVEL READ COMMITTED; }
@@ -312,6 +313,10 @@ step sysmerge2	{
 step c2	{ COMMIT; }
 step r2	{ ROLLBACK; }
 
+step s2pp1 { SET plan_cache_mode TO force_generic_plan; }
+step s2pp2 { PREPARE epd AS DELETE FROM another_parttbl WHERE a = $1; }
+step s2pp3 { EXECUTE epd(1); }
+
 session s3
 setup		{ BEGIN ISOLATION LEVEL READ COMMITTED; }
 step read	{ SELECT * FROM accounts ORDER BY accountid; }
@@ -415,3 +420,6 @@ permutation simplepartupdate_noroute complexpartupdate_doesnt_route c1 c2 read_p
 
 permutation sys1 sysupd2 c1 c2
 permutation sys1 sysmerge2 c1 c2
+
+# Exercise run-time partition pruning code in an EPQ recheck
+permutation s1pp1 s2pp1 s2pp2 s2pp3 c1 c2