pg_dump: Add description for GPDB handling of public schema.
Authored-by: Brent Doil
@@ -4580,10 +4580,11 @@ binary_upgrade_set_namespace_oid(Archive *fout, PQExpBuffer upgrade_buffer,
/*
* In PostgreSQL, the creation of the public schema is not dumped, because
* it's assumed to exist in a new cluster. But in GPDB, we need to re-create
- * it, so that we can set its OID.
- *
- * GPDB_12_MERGE_FIXME: Or could we rely that it has the same built-in
- * OID on all nodes?
+ * it, so that we can set its OID. This change is required because Oid
+ * preassignment during upgrade requires the namespace. If the public
+ * schema is not re-created, Oid preassignments in public will be
+ * mismatched between old and new cluster if the schema had been
+ * dropped and recreated on the old cluster.
*/
if (strcmp(pg_nspname, "public") == 0)
{
