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 <[email protected]>
Author: Tender Wang <[email protected]>
Reviewed-by: Gurjeet Singh <[email protected]>
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 84ccd7d457de910aeb18937fdcff289ca9140b3b..0374476ffad9ea8f13518cd71aaab34e427dc0dd 100644 (file)
--- a/src/backend/executor/execPartition.c
+++ b/src/backend/executor/execPartition.c
@@ -876,7 +876,7 @@ 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)
@@ -956,6 +956,8 @@ 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 87c820276a8f79b0214e2479ff0dc2a3a130fc1d..309e27f8b5faa57b942b7195af9314b4b06a9f4b 100644 (file)
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -3784,7 +3784,7 @@ 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 c8ecc8b6b4abba697b936bb005cd695ee02c2a9e..bcd296682975cec557531b1cee1237bf70d3ebbc 100644 (file)
--- a/src/test/regress/expected/merge.out
+++ b/src/test/regress/expected/merge.out
@@ -2060,6 +2060,23 @@ SELECT * FROM pa_target ORDER BY tid;
   15 |    1500 | initial
 (8 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 07b6295b3bae7969036e7262d65911b0c4786269..f7a19c0e7dd7d99fdb085ed25da97007622cb96a 100644 (file)
--- a/src/test/regress/sql/merge.sql
+++ b/src/test/regress/sql/merge.sql
@@ -1271,6 +1271,19 @@ MERGE INTO pa_target t
 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