Fix uninitialized index information access during apply.

The issue happens when building conflict information during apply of
INSERT or UPDATE operations that violate unique constraints on leaf
partitions.

The problem was introduced in commit 9ff68679b5, which removed the
redundant calls to ExecOpenIndices/ExecCloseIndices. The previous code was
relying on the redundant ExecOpenIndices call in
apply_handle_tuple_routing() to build the index information required for
unique key conflict detection.

The fix is to delay building the index information until a conflict is
detected instead of relying on ExecOpenIndices to do the same. The
additional benefit of this approach is that it avoids building index
information when there is no conflict.

Author: Hou Zhijie <houzj.fnst@fujitsu.com>
Reviewed-by:Reviewed-by: Amit Kapila <amit.kapila16@gmail.com>
Discussion: https://postgr.es/m/TYAPR01MB57244ADA33DDA57119B9D26494A62@TYAPR01MB5724.jpnprd01.prod.outlook.com

src/backend/executor/execIndexing.c

@@ -214,9 +214,8 @@ ExecOpenIndices(ResultRelInfo *resultRelInfo, bool speculative)
 		ii = BuildIndexInfo(indexDesc);
 
 		/*
-		 * If the indexes are to be used for speculative insertion or conflict
+		 * If the indexes are to be used for speculative insertion, add extra
-		 * detection in logical replication, add extra information required by
+		 * information required by unique index entries.
-		 * unique index entries.
 		 */
 		if (speculative && ii->ii_Unique && !indexDesc->rd_index->indisexclusion)
 			BuildSpeculativeIndexInfo(indexDesc, ii);

src/backend/executor/execReplication.c

@@ -431,6 +431,30 @@ retry:
 	return found;
 }
 
+/*
+ * Build additional index information necessary for conflict detection.
+ */
+static void
+BuildConflictIndexInfo(ResultRelInfo *resultRelInfo, Oid conflictindex)
+{
+	for (int i = 0; i < resultRelInfo->ri_NumIndices; i++)
+	{
+		Relation	indexRelation = resultRelInfo->ri_IndexRelationDescs[i];
+		IndexInfo  *indexRelationInfo = resultRelInfo->ri_IndexRelationInfo[i];
+
+		if (conflictindex != RelationGetRelid(indexRelation))
+			continue;
+
+		/*
+		 * This Assert will fail if BuildSpeculativeIndexInfo() is called
+		 * twice for the given index.
+		 */
+		Assert(indexRelationInfo->ii_UniqueOps == NULL);
+
+		BuildSpeculativeIndexInfo(indexRelation, indexRelationInfo);
+	}
+}
+
 /*
  * Find the tuple that violates the passed unique index (conflictindex).
  *
@@ -452,6 +476,12 @@ FindConflictTuple(ResultRelInfo *resultRelInfo, EState *estate,
 
 	*conflictslot = NULL;
 
+	/*
+	 * Build additional information required to check constraints violations.
+	 * See check_exclusion_or_unique_constraint().
+	 */
+	BuildConflictIndexInfo(resultRelInfo, conflictindex);
+
 retry:
 	if (ExecCheckIndexConstraints(resultRelInfo, slot, estate,
 								  &conflictTid, &slot->tts_tid,

src/backend/replication/logical/worker.c

@@ -2457,7 +2457,7 @@ apply_handle_insert(StringInfo s)
 	{
 		ResultRelInfo *relinfo = edata->targetRelInfo;
 
-		ExecOpenIndices(relinfo, true);
+		ExecOpenIndices(relinfo, false);
 		apply_handle_insert_internal(edata, relinfo, remoteslot);
 		ExecCloseIndices(relinfo);
 	}
@@ -2680,7 +2680,7 @@ apply_handle_update_internal(ApplyExecutionData *edata,
 	MemoryContext oldctx;
 
 	EvalPlanQualInit(&epqstate, estate, NULL, NIL, -1, NIL);
-	ExecOpenIndices(relinfo, true);
+	ExecOpenIndices(relinfo, false);
 
 	found = FindReplTupleInLocalRel(edata, localrel,
 									&relmapentry->remoterel,

src/test/subscription/t/035_conflicts.pl

@@ -25,14 +25,23 @@ $node_subscriber->start;
 $node_publisher->safe_psql('postgres',
 	"CREATE TABLE conf_tab (a int PRIMARY KEY, b int UNIQUE, c int UNIQUE);");
 
+$node_publisher->safe_psql('postgres',
+	"CREATE TABLE conf_tab_2 (a int PRIMARY KEY, b int UNIQUE, c int UNIQUE);");
+
 # Create same table on subscriber
 $node_subscriber->safe_psql('postgres',
 	"CREATE TABLE conf_tab (a int PRIMARY key, b int UNIQUE, c int UNIQUE);");
 
+$node_subscriber->safe_psql(
+	'postgres', qq[
+	 CREATE TABLE conf_tab_2 (a int PRIMARY KEY, b int, c int, unique(a,b)) PARTITION BY RANGE (a);
+	 CREATE TABLE conf_tab_2_p1 PARTITION OF conf_tab_2 FOR VALUES FROM (MINVALUE) TO (100);
+]);
+
 # Setup logical replication
 my $publisher_connstr = $node_publisher->connstr . ' dbname=postgres';
 $node_publisher->safe_psql('postgres',
-	"CREATE PUBLICATION pub_tab FOR TABLE conf_tab");
+	"CREATE PUBLICATION pub_tab FOR TABLE conf_tab, conf_tab_2");
 
 # Create the subscription
 my $appname = 'sub_tab';
@@ -110,4 +119,30 @@ $node_subscriber->wait_for_log(
 
 pass('multiple_unique_conflicts detected during update');
 
+# Truncate table to get rid of the error
+$node_subscriber->safe_psql('postgres', "TRUNCATE conf_tab;");
+
+
+##################################################
+# Test multiple_unique_conflicts due to INSERT on a leaf partition
+##################################################
+
+# Insert data in the subscriber table
+$node_subscriber->safe_psql('postgres',
+	"INSERT INTO conf_tab_2 VALUES (55,2,3);");
+
+# Insert data in the publisher table
+$node_publisher->safe_psql('postgres',
+	"INSERT INTO conf_tab_2 VALUES (55,2,3);");
+
+$node_subscriber->wait_for_log(
+	qr/conflict detected on relation \"public.conf_tab_2_p1\": conflict=multiple_unique_conflicts.*
+.*Key already exists in unique index \"conf_tab_2_p1_pkey\".*
+.*Key \(a\)=\(55\); existing local tuple \(55, 2, 3\); remote tuple \(55, 2, 3\).*
+.*Key already exists in unique index \"conf_tab_2_p1_a_b_key\".*
+.*Key \(a, b\)=\(55, 2\); existing local tuple \(55, 2, 3\); remote tuple \(55, 2, 3\)./,
+	$log_offset);
+
+pass('multiple_unique_conflicts detected on a leaf partition during insert');
+
 done_testing();