Fix MERGE with DO NOTHING actions into a partitioned table.

ExecInitPartitionInfo() duplicates much of the logic in
ExecInitMerge(), except that it failed to handle DO NOTHING
actions. This would cause an "unknown action in MERGE WHEN clause"
error if a MERGE with any DO NOTHING actions attempted to insert into
a partition not already initialised by ExecInitModifyTable().

Bug: #18871
Reported-by: Alexander Lakhin <exclusion@gmail.com>
Author: Tender Wang <tndrwang@gmail.com>
Reviewed-by: Gurjeet Singh <gurjeet@singh.im>
Discussion: https://postgr.es/m/18871-b44e3c96de3bd2e8%40postgresql.org
Backpatch-through: 15

diff --git a/src/backend/executor/execPartition.c b/src/backend/executor/execPartition.c
index 6de40aacfa541a0ccd6dd55cf0256bf92066b1ce..f56117bbae8e7e68ce4836da36438abfced70ea6 100644 (file)
--- a/src/backend/executor/execPartition.c
+++ b/src/backend/executor/execPartition.c
@@ -873,7 +873,7 @@ ExecInitPartitionInfo(ModifyTableState *mtstate, EState *estate,
         * reference and make copy for this relation, converting stuff that
         * references attribute numbers to match this relation's.
         *
-        * This duplicates much of the logic in ExecInitMerge(), so something
+        * This duplicates much of the logic in ExecInitMerge(), so if something
         * changes there, look here too.
         */
        if (node && node->operation == CMD_MERGE)
@@ -944,6 +944,8 @@ ExecInitPartitionInfo(ModifyTableState *mtstate, EState *estate,
                                                                                                  NULL);
                                        break;
                                case CMD_DELETE:
+                               case CMD_NOTHING:
+                                       /* Nothing to do */
                                        break;
 
                                default:

diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index b4cd02786954e1263904f9fffc7f98a18854deba..94d7117ad61dba23ae8a541394fbcff60533af1a 100644 (file)
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -3443,7 +3443,7 @@ ExecInitMerge(ModifyTableState *mtstate, EState *estate)
                                case CMD_NOTHING:
                                        break;
                                default:
-                                       elog(ERROR, "unknown operation");
+                                       elog(ERROR, "unknown action in MERGE WHEN clause");
                                        break;
                        }
                }

diff --git a/src/test/regress/expected/merge.out b/src/test/regress/expected/merge.out
index bc9a59803fce5c496cdd53c7a944c4d3351b0339..5d1be9f6b24589df2a01b255cbf091dc0d002909 100644 (file)
--- a/src/test/regress/expected/merge.out
+++ b/src/test/regress/expected/merge.out
@@ -1698,6 +1698,23 @@ SELECT * FROM pa_target ORDER BY tid;
   14 |     140 | inserted by merge
 (14 rows)
 
+ROLLBACK;
+-- bug #18871: ExecInitPartitionInfo()'s handling of DO NOTHING actions
+BEGIN;
+TRUNCATE pa_target;
+MERGE INTO pa_target t
+  USING (VALUES (10, 100)) AS s(sid, delta)
+  ON t.tid = s.sid
+  WHEN NOT MATCHED THEN
+    INSERT VALUES (1, 10, 'inserted by merge')
+  WHEN MATCHED THEN
+    DO NOTHING;
+SELECT * FROM pa_target ORDER BY tid, val;
+ tid | balance |        val        
+-----+---------+-------------------
+   1 |      10 | inserted by merge
+(1 row)
+
 ROLLBACK;
 DROP TABLE pa_target CASCADE;
 -- The target table is partitioned in the same way, but this time by attaching

diff --git a/src/test/regress/sql/merge.sql b/src/test/regress/sql/merge.sql
index 2a220a248f1d05d217bcd1a3ae74240438eb73a1..4609241b2a580f138fe8a15d37ad77e2026a6433 100644 (file)
--- a/src/test/regress/sql/merge.sql
+++ b/src/test/regress/sql/merge.sql
@@ -1060,6 +1060,19 @@ SELECT merge_func();
 SELECT * FROM pa_target ORDER BY tid;
 ROLLBACK;
 
+-- bug #18871: ExecInitPartitionInfo()'s handling of DO NOTHING actions
+BEGIN;
+TRUNCATE pa_target;
+MERGE INTO pa_target t
+  USING (VALUES (10, 100)) AS s(sid, delta)
+  ON t.tid = s.sid
+  WHEN NOT MATCHED THEN
+    INSERT VALUES (1, 10, 'inserted by merge')
+  WHEN MATCHED THEN
+    DO NOTHING;
+SELECT * FROM pa_target ORDER BY tid, val;
+ROLLBACK;
+
 DROP TABLE pa_target CASCADE;
 
 -- The target table is partitioned in the same way, but this time by attaching