Fix ON CONFLICT DO UPDATE for tables with oids.

When taking the UPDATE path in an INSERT .. ON CONFLICT .. UPDATE tables
with oids were not supported. The tuple generated by the update target
list was projected without space for an oid - a simple oversight.

Reported-By: Peter Geoghegan
Author: Andres Freund
Backpatch: 9.5, where ON CONFLICT was introduced

src/backend/executor/nodeModifyTable.c

@@ -1678,7 +1678,7 @@ ExecInitModifyTable(ModifyTable *node, EState *estate, int eflags)
 
 		/* create target slot for UPDATE SET projection */
 		tupDesc = ExecTypeFromTL((List *) node->onConflictSet,
-								 false);
+						 resultRelInfo->ri_RelationDesc->rd_rel->relhasoids);
 		mtstate->mt_conflproj = ExecInitExtraTupleSlot(mtstate->ps.state);
 		ExecSetSlotDescriptor(mtstate->mt_conflproj, tupDesc);
 

src/test/regress/expected/insert_conflict.out

@@ -507,3 +507,62 @@ insert into excluded values(1, '2') on conflict (key) do update set data = 3 RET
 
 -- clean up
 drop table excluded;
+-- Check tables w/o oids are handled correctly
+create table testoids(key int primary key, data text) without oids;
+-- first without oids
+insert into testoids values(1, '1') on conflict (key) do update set data = excluded.data RETURNING *;
+ key | data 
+-----+------
+   1 | 1
+(1 row)
+
+insert into testoids values(1, '2') on conflict (key) do update set data = excluded.data RETURNING *;
+ key | data 
+-----+------
+   1 | 2
+(1 row)
+
+-- add oids
+alter table testoids set with oids;
+-- update existing row, that didn't have an oid
+insert into testoids values(1, '3') on conflict (key) do update set data = excluded.data RETURNING *;
+ key | data 
+-----+------
+   1 | 3
+(1 row)
+
+-- insert a new row
+insert into testoids values(2, '1') on conflict (key) do update set data = excluded.data RETURNING *;
+ key | data 
+-----+------
+   2 | 1
+(1 row)
+
+-- and update it
+insert into testoids values(2, '2') on conflict (key) do update set data = excluded.data RETURNING *;
+ key | data 
+-----+------
+   2 | 2
+(1 row)
+
+-- remove oids again, test
+alter table testoids set without oids;
+insert into testoids values(1, '4') on conflict (key) do update set data = excluded.data RETURNING *;
+ key | data 
+-----+------
+   1 | 4
+(1 row)
+
+insert into testoids values(3, '1') on conflict (key) do update set data = excluded.data RETURNING *;
+ key | data 
+-----+------
+   3 | 1
+(1 row)
+
+insert into testoids values(3, '2') on conflict (key) do update set data = excluded.data RETURNING *;
+ key | data 
+-----+------
+   3 | 2
+(1 row)
+
+DROP TABLE testoids;

src/test/regress/sql/insert_conflict.sql

@@ -295,3 +295,25 @@ insert into excluded values(1, '2') on conflict (key) do update set data = 3 RET
 
 -- clean up
 drop table excluded;
+
+
+-- Check tables w/o oids are handled correctly
+create table testoids(key int primary key, data text) without oids;
+-- first without oids
+insert into testoids values(1, '1') on conflict (key) do update set data = excluded.data RETURNING *;
+insert into testoids values(1, '2') on conflict (key) do update set data = excluded.data RETURNING *;
+-- add oids
+alter table testoids set with oids;
+-- update existing row, that didn't have an oid
+insert into testoids values(1, '3') on conflict (key) do update set data = excluded.data RETURNING *;
+-- insert a new row
+insert into testoids values(2, '1') on conflict (key) do update set data = excluded.data RETURNING *;
+-- and update it
+insert into testoids values(2, '2') on conflict (key) do update set data = excluded.data RETURNING *;
+-- remove oids again, test
+alter table testoids set without oids;
+insert into testoids values(1, '4') on conflict (key) do update set data = excluded.data RETURNING *;
+insert into testoids values(3, '1') on conflict (key) do update set data = excluded.data RETURNING *;
+insert into testoids values(3, '2') on conflict (key) do update set data = excluded.data RETURNING *;
+
+DROP TABLE testoids;