1 files changed, 34 insertions, 0 deletions
diff --git a/src/backend/access/common/tupdesc.c b/src/backend/access/common/tupdesc.c
index fb5c199c0c4..11c31d8fe92 100644
--- a/src/backend/access/common/tupdesc.c
+++ b/src/backend/access/common/tupdesc.c
@@ -158,6 +158,40 @@ CreateTupleDescCopy(TupleDesc tupdesc)
 }
 
 /*
+ * CreateTupleDescCopyExtend
+ *		This function creates a new TupleDesc by copying from an existing
+ *		TupleDesc, but adding space for more columns. The new tupdesc is
+ *      not regarded as the same record type as the old one (and therefore
+ *      does not inherit its typeid/typmod, which instead are left as an
+ *      anonymous record type).
+ *
+ *      The additional column slots are not initialized in any way;
+ *      callers must do their own TupleDescInitEntry on each.
+ *
+ * !!! Constraints and defaults are not copied !!!
+ */
+TupleDesc
+CreateTupleDescCopyExtend(TupleDesc tupdesc, int moreatts)
+{
+	TupleDesc	desc;
+	int			i;
+	int         src_natts = tupdesc->natts;
+
+	Assert(moreatts >= 0);
+
+	desc = CreateTemplateTupleDesc(src_natts + moreatts, tupdesc->tdhasoid);
+
+	for (i = 0; i < src_natts; i++)
+	{
+		memcpy(desc->attrs[i], tupdesc->attrs[i], ATTRIBUTE_FIXED_PART_SIZE);
+		desc->attrs[i]->attnotnull = false;
+		desc->attrs[i]->atthasdef = false;
+	}
+
+	return desc;
+}
+
+/*
  * CreateTupleDescCopyConstr
  *		This function creates a new TupleDesc by copying from an existing
  *		TupleDesc (including its constraints and defaults).