we should check if relation is valid after fetching a relation

src/backend/columnar/columnar_customscan.c

@@ -277,6 +277,11 @@ ColumnarSetRelPathlistHook(PlannerInfo *root, RelOptInfo *rel, Index rti,
 	 * into the scan of the table to minimize the data read.
 	 */
 	Relation relation = RelationIdGetRelation(rte->relid);
+	if (!RelationIsValid(relation))
+	{
+		ereport(ERROR, (errmsg("could not open relation with OID %u", rte->relid)));
+	}
+
 	if (relation->rd_tableam == GetColumnarTableAmRoutine())
 	{
 		if (rte->tablesample != NULL)
@@ -501,6 +506,11 @@ ColumnarIndexScanAdditionalCost(PlannerInfo *root, RelOptInfo *rel,
 				   &indexCorrelation, &fakeIndexPages);
 
 	Relation relation = RelationIdGetRelation(relationId);
+	if (!RelationIsValid(relation))
+	{
+		ereport(ERROR, (errmsg("could not open relation with OID %u", relationId)));
+	}
+
 	uint64 rowCount = ColumnarTableRowCount(relation);
 	RelationClose(relation);
 	double estimatedRows = rowCount * indexSelectivity;
@@ -596,6 +606,11 @@ static int
 RelationIdGetNumberOfAttributes(Oid relationId)
 {
 	Relation relation = RelationIdGetRelation(relationId);
+	if (!RelationIsValid(relation))
+	{
+		ereport(ERROR, (errmsg("could not open relation with OID %u", relationId)));
+	}
+
 	int nattrs = relation->rd_att->natts;
 	RelationClose(relation);
 	return nattrs;
@@ -1399,6 +1414,11 @@ static Cost
 ColumnarPerStripeScanCost(RelOptInfo *rel, Oid relationId, int numberOfColumnsRead)
 {
 	Relation relation = RelationIdGetRelation(relationId);
+	if (!RelationIsValid(relation))
+	{
+		ereport(ERROR, (errmsg("could not open relation with OID %u", relationId)));
+	}
+
 	List *stripeList = StripesForRelfilenode(relation->rd_node);
 	RelationClose(relation);
 
@@ -1451,6 +1471,11 @@ static uint64
 ColumnarTableStripeCount(Oid relationId)
 {
 	Relation relation = RelationIdGetRelation(relationId);
+	if (!RelationIsValid(relation))
+	{
+		ereport(ERROR, (errmsg("could not open relation with OID %u", relationId)));
+	}
+
 	List *stripeList = StripesForRelfilenode(relation->rd_node);
 	int stripeCount = list_length(stripeList);
 	RelationClose(relation);

src/backend/distributed/commands/alter_table.c

@@ -857,6 +857,11 @@ static void
 DropIndexesNotSupportedByColumnar(Oid relationId, bool suppressNoticeMessages)
 {
 	Relation columnarRelation = RelationIdGetRelation(relationId);
+	if (!RelationIsValid(columnarRelation))
+	{
+		ereport(ERROR, (errmsg("could not open relation with OID %u", relationId)));
+	}
+
 	List *indexIdList = RelationGetIndexList(columnarRelation);
 
 	/*

src/backend/distributed/commands/citus_add_local_table_to_metadata.c

@@ -891,6 +891,11 @@ static void
 RenameShardRelationStatistics(Oid shardRelationId, uint64 shardId)
 {
 	Relation shardRelation = RelationIdGetRelation(shardRelationId);
+	if (!RelationIsValid(shardRelation))
+	{
+		ereport(ERROR, (errmsg("could not open relation with OID %u", shardRelationId)));
+	}
+
 	List *statsOidList = RelationGetStatExtList(shardRelation);
 	RelationClose(shardRelation);
 

src/backend/distributed/commands/index.c

@@ -321,6 +321,11 @@ ExecuteFunctionOnEachTableIndex(Oid relationId, PGIndexProcessor pgIndexProcesso
 	List *result = NIL;
 
 	Relation relation = RelationIdGetRelation(relationId);
+	if (!RelationIsValid(relation))
+	{
+		ereport(ERROR, (errmsg("could not open relation with OID %u", relationId)));
+	}
+
 	List *indexIdList = RelationGetIndexList(relation);
 	Oid indexId = InvalidOid;
 	foreach_oid(indexId, indexIdList)

src/backend/distributed/commands/statistics.c

@@ -469,6 +469,11 @@ GetExplicitStatisticsCommandList(Oid relationId)
 	List *explicitStatisticsCommandList = NIL;
 
 	Relation relation = RelationIdGetRelation(relationId);
+	if (!RelationIsValid(relation))
+	{
+		ereport(ERROR, (errmsg("could not open relation with OID %u", relationId)));
+	}
+
 	List *statisticsIdList = RelationGetStatExtList(relation);
 	RelationClose(relation);
 
@@ -540,6 +545,11 @@ GetExplicitStatisticsSchemaIdList(Oid relationId)
 	List *schemaIdList = NIL;
 
 	Relation relation = RelationIdGetRelation(relationId);
+	if (!RelationIsValid(relation))
+	{
+		ereport(ERROR, (errmsg("could not open relation with OID %u", relationId)));
+	}
+
 	List *statsIdList = RelationGetStatExtList(relation);
 	RelationClose(relation);
 

src/backend/distributed/utils/multi_partitioning_utils.c

@@ -506,6 +506,11 @@ CreateFixPartitionShardIndexNamesTaskList(Oid parentRelationId, Oid partitionRel
 	}
 
 	Relation parentRelation = RelationIdGetRelation(parentRelationId);
+	if (!RelationIsValid(parentRelation))
+	{
+		ereport(ERROR, (errmsg("could not open relation with OID %u", parentRelationId)));
+	}
+
 	List *parentIndexIdList = NIL;
 
 	if (parentIndexOid != InvalidOid)