Columnar temp tables cannot be accessed(#8235).

Fix PR comments.

src/backend/columnar/columnar_metadata.c

@@ -1323,9 +1323,9 @@ GetHighestUsedAddress(Relation rel)
  * In case if relid hasn't been defined yet, we should use RelidByRelfilenumber
  * to get correct relid value.
  *
- * Now it is basically used for temp rels, because since PG13 RelidByRelfilenumber
- * skip temp relations and we should use alternative ways to get relid value in case
- * of temp objects.
+ * Now it is basically used for temp rels, because since PG18(it was backpatched
+ * through PG13) RelidByRelfilenumber skip temp relations and we should use
+ * alternative ways to get relid value in case of temp objects.
  */
 Oid
 ColumnarRelationId(Oid relid, RelFileLocator relfilelocator)

src/backend/columnar/columnar_writer.c

@@ -47,7 +47,12 @@ struct ColumnarWriteState
 	TupleDesc tupleDescriptor;
 	FmgrInfo **comparisonFunctionArray;
 	RelFileLocator relfilelocator;
-	Oid temp_relid;          /* We can't rely on RelidByRelfilenumber for temp tables since PG18.*/
+
+	/*
+	 * We can't rely on RelidByRelfilenumber for temp tables since
+	 * PG18(it was backpatched through PG13).
+	 */
+	Oid temp_relid;
 
 	MemoryContext stripeWriteContext;
 	MemoryContext perTupleContext;

src/include/columnar/columnar.h

@@ -65,9 +65,9 @@
 #define CITUS_COLUMNAR_INTERNAL_VERSION "11.1-0"
 
 /*
- * We can't rely on RelidByRelfilenumber for temp tables since PG13, so we can use
- * this macro to define relid within relation in case of temp relations. Otherwise
- * RelidByRelfilenumber should be used.
+ * We can't rely on RelidByRelfilenumber for temp tables since PG18(it was backpatched
+ * through PG13), so we can use this macro to define relid within relation in case of
+ * temp relations. Otherwise RelidByRelfilenumber should be used.
  */
 #define RelationPrecomputeOid(a) (RelationUsesLocalBuffers(a) ? RelationGetRelid(a) : \
 								  InvalidOid)