I wrote:
> The planner is reducing the scan of target_parted to
> a dummy scan, as is reasonable, but it forgets to
> provide ctid as an output from that scan; then the
> parent join node is unhappy because it does have
> a ctid output. So it looks like the problem is some
> shortcut we take while creating the dummy scan.
Oh, actually the problem is in distribute_row_identity_vars,
which is supposed to handle this case, but it thinks it doesn't
have to back-fill the rel's reltarget. Wrong. Now that I see
the problem, I wonder if we can't reproduce a similar symptom
without MERGE, which would mean that v14 has the issue too.
The attached seems to fix it, but I'm going to look for a
non-MERGE test case before pushing.
regards, tom lane
diff --git a/src/backend/optimizer/util/appendinfo.c b/src/backend/optimizer/util/appendinfo.c
index 9d377385f1..c1b1557570 100644
--- a/src/backend/optimizer/util/appendinfo.c
+++ b/src/backend/optimizer/util/appendinfo.c
@@ -21,6 +21,7 @@
#include "nodes/nodeFuncs.h"
#include "optimizer/appendinfo.h"
#include "optimizer/pathnode.h"
+#include "optimizer/planmain.h"
#include "parser/parsetree.h"
#include "utils/lsyscache.h"
#include "utils/rel.h"
@@ -994,9 +995,10 @@ distribute_row_identity_vars(PlannerInfo *root)
* certainly process no rows. Handle this edge case by re-opening the top
* result relation and adding the row identity columns it would have used,
* as preprocess_targetlist() would have done if it weren't marked "inh".
- * (This is a bit ugly, but it seems better to confine the ugliness and
- * extra cycles to this unusual corner case.) We needn't worry about
- * fixing the rel's reltarget, as that won't affect the finished plan.
+ * Then re-run build_base_rel_tlists() to ensure that the added columns
+ * get propagated to the relation's reltarget. (This is a bit ugly, but
+ * it seems better to confine the ugliness and extra cycles to this
+ * unusual corner case.)
*/
if (root->row_identity_vars == NIL)
{
@@ -1006,6 +1008,8 @@ distribute_row_identity_vars(PlannerInfo *root)
add_row_identity_columns(root, result_relation,
target_rte, target_relation);
table_close(target_relation, NoLock);
+ build_base_rel_tlists(root, root->processed_tlist);
+ /* There are no ROWID_VAR Vars in this case, so we're done. */
return;
}
