Assorted code improvements for table partitioning.

Michael Paquier, per Coverity.

src/backend/catalog/heap.c

@@ -3248,6 +3248,10 @@ StorePartitionBound(Relation rel, Relation parent, Node *bound)
 	classRel = heap_open(RelationRelationId, RowExclusiveLock);
 	tuple = SearchSysCacheCopy1(RELOID,
 								ObjectIdGetDatum(RelationGetRelid(rel)));
+	if (!HeapTupleIsValid(tuple))
+		elog(ERROR, "cache lookup failed for relation %u",
+			 RelationGetRelid(rel));
+
 #ifdef USE_ASSERT_CHECKING
 	{
 		Form_pg_class	classForm;

src/backend/catalog/partition.c

@@ -200,6 +200,8 @@ RelationBuildPartitionDesc(Relation rel)
 		Node	   *boundspec;
 
 		tuple = SearchSysCache1(RELOID, inhrelid);
+		if (!HeapTupleIsValid(tuple))
+			elog(ERROR, "cache lookup failed for relation %u", inhrelid);
 
 		/*
 		 * It is possible that the pg_class tuple of a partition has not been
@@ -1516,6 +1518,10 @@ generate_partition_qual(Relation rel)
 		elog(ERROR, "relation \"%s\" has relispartition = false",
 			 RelationGetRelationName(rel));
 	tuple = SearchSysCache1(RELOID, RelationGetRelid(rel));
+	if (!HeapTupleIsValid(tuple))
+		elog(ERROR, "cache lookup failed for relation %u",
+			 RelationGetRelid(rel));
+
 	boundDatum = SysCacheGetAttr(RELOID, tuple,
 								 Anum_pg_class_relpartbound,
 								 &isnull);

src/bin/pg_dump/pg_dump.c

@@ -5736,7 +5736,7 @@ getPartitions(Archive *fout, int *numPartitions)
 	PGresult   *res;
 	int			ntups;
 	int			i;
-	PQExpBuffer query = createPQExpBuffer();
+	PQExpBuffer query;
 	PartInfo    *partinfo;
 
 	int			i_partrelid;
@@ -5750,6 +5750,8 @@ getPartitions(Archive *fout, int *numPartitions)
 		return NULL;
 	}
 
+	query = createPQExpBuffer();
+
 	/* Make sure we are in proper schema */
 	selectSourceSchema(fout, "pg_catalog");
 
@@ -7067,7 +7069,7 @@ getTransforms(Archive *fout, int *numTransforms)
 void
 getTablePartitionKeyInfo(Archive *fout, TableInfo *tblinfo, int numTables)
 {
-	PQExpBuffer q = createPQExpBuffer();
+	PQExpBuffer q;
 	int			i;
 	PGresult   *res;
 
@@ -7075,6 +7077,8 @@ getTablePartitionKeyInfo(Archive *fout, TableInfo *tblinfo, int numTables)
 	if (fout->remoteVersion < 100000)
 		return;
 
+	q = createPQExpBuffer();
+
 	for (i = 0; i < numTables; i++)
 	{
 		TableInfo  *tbinfo = &(tblinfo[i]);
@@ -7094,6 +7098,8 @@ getTablePartitionKeyInfo(Archive *fout, TableInfo *tblinfo, int numTables)
 		Assert(PQntuples(res) == 1);
 		tbinfo->partkeydef = pg_strdup(PQgetvalue(res, 0, 0));
 	}
+
+	destroyPQExpBuffer(q);
 }
 
 /*