Support PlaceHolderVars in MERGE actions.

preprocess_targetlist thought PHVs couldn't appear here.
It was mistaken, as per report from Önder Kalacı.

Surveying other pull_var_clause calls, I noted no similar errors,
but I did notice that qual_is_pushdown_safe's assertion about
!contain_window_function was pointless, because the following
pull_var_clause call would complain about them anyway.  In HEAD
only, remove the redundant Assert and improve the commentary.

Discussion: https://postgr.es/m/CACawEhUuum-gC_2S3sXLTcsk7bUSPSHOD+g1ZpfKaDK-KKPPWA@mail.gmail.com

diff --git a/src/backend/optimizer/prep/preptlist.c b/src/backend/optimizer/prep/preptlist.c
index 137b28323d6429f398a2b2c535da20609078a7e7..133966b6250616b3330371cddbfff87ea14fe9b9 100644 (file)
--- a/src/backend/optimizer/prep/preptlist.c
+++ b/src/backend/optimizer/prep/preptlist.c
@@ -155,17 +155,15 @@ preprocess_targetlist(PlannerInfo *root)
                    extract_update_targetlist_colnos(action->targetList);
 
            /*
-            * Add resjunk entries for any Vars used in each action's
-            * targetlist and WHEN condition that belong to relations other
-            * than target.  Note that aggregates, window functions and
-            * placeholder vars are not possible anywhere in MERGE's WHEN
-            * clauses.  (PHVs may be added later, but they don't concern us
-            * here.)
+            * Add resjunk entries for any Vars and PlaceHolderVars used in
+            * each action's targetlist and WHEN condition that belong to
+            * relations other than the target.  We don't expect to see any
+            * aggregates or window functions here.
             */
            vars = pull_var_clause((Node *)
                                   list_concat_copy((List *) action->qual,
                                                    action->targetList),
-                                  0);
+                                  PVC_INCLUDE_PLACEHOLDERS);
            foreach(l2, vars)
            {
                Var        *var = (Var *) lfirst(l2);

diff --git a/src/test/regress/expected/merge.out b/src/test/regress/expected/merge.out
index 35abffde7d27752fe40da48ffae33b236190b601..81c6d97d75389c0135f750e5bd8bd440477e777f 100644 (file)
--- a/src/test/regress/expected/merge.out
+++ b/src/test/regress/expected/merge.out
@@ -1902,6 +1902,27 @@ SELECT * FROM cj_target;
    2 |     320 | initial source2 300
 (4 rows)
 
+-- try it with an outer join and PlaceHolderVar
+MERGE INTO cj_target t
+USING (SELECT *, 'join input'::text AS phv FROM cj_source1) fj
+   FULL JOIN cj_source2 fj2 ON fj.scat = fj2.sid2 * 10
+ON t.tid = fj.scat
+WHEN NOT MATCHED THEN
+   INSERT (tid, balance, val) VALUES (fj.scat, fj.delta, fj.phv);
+SELECT * FROM cj_target;
+ tid | balance |               val                
+-----+---------+----------------------------------
+   3 |     400 | initial source2 updated by merge
+   1 |     220 | initial source2 200
+   1 |     110 | initial source2 200
+   2 |     320 | initial source2 300
+  10 |     100 | join input
+  10 |     400 | join input
+  20 |     200 | join input
+  20 |     300 | join input
+     |         | 
+(9 rows)
+
 ALTER TABLE cj_source1 RENAME COLUMN sid1 TO sid;
 ALTER TABLE cj_source2 RENAME COLUMN sid2 TO sid;
 TRUNCATE cj_target;

diff --git a/src/test/regress/sql/merge.sql b/src/test/regress/sql/merge.sql
index cae6902f2c327773a2e876d368625e8da779bb51..29a35486d01d26af96bc59baaf19d8a869193428 100644 (file)
--- a/src/test/regress/sql/merge.sql
+++ b/src/test/regress/sql/merge.sql
@@ -1225,6 +1225,16 @@ WHEN MATCHED THEN
 
 SELECT * FROM cj_target;
 
+-- try it with an outer join and PlaceHolderVar
+MERGE INTO cj_target t
+USING (SELECT *, 'join input'::text AS phv FROM cj_source1) fj
+   FULL JOIN cj_source2 fj2 ON fj.scat = fj2.sid2 * 10
+ON t.tid = fj.scat
+WHEN NOT MATCHED THEN
+   INSERT (tid, balance, val) VALUES (fj.scat, fj.delta, fj.phv);
+
+SELECT * FROM cj_target;
+
 ALTER TABLE cj_source1 RENAME COLUMN sid1 TO sid;
 ALTER TABLE cj_source2 RENAME COLUMN sid2 TO sid;