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 7651886229114a380d9299172cdd14b15ca01821..a3602b816871e0ac43867a9d229d2ad31eaaab82 100644 (file)
--- a/src/backend/executor/execPartition.c
+++ b/src/backend/executor/execPartition.c
@@ -872,7 +872,7 @@ 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)
@@ -952,6 +952,8 @@ 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 02be41845accdae2a41ba75d8eda1c803a2c86f6..d84e6dba45ac4b85c687c238ff1e9e607a63e3b3 100644 (file)
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -3600,7 +3600,7 @@ 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 521d70a8919868098907bca4198a7ac9b89b538e..e9c9b15d3c80dc0519d6873a95a4b1d5458141a1 100644 (file)
--- a/src/test/regress/expected/merge.out
+++ b/src/test/regress/expected/merge.out
@@ -2058,6 +2058,23 @@ 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 5ddcca84f829268a06fe4ece76688419b13496f2..556777e4f4b51a5274bf46eb4f3baeb5ab2a34b8 100644 (file)
--- a/src/test/regress/sql/merge.sql
+++ b/src/test/regress/sql/merge.sql
@@ -1269,6 +1269,19 @@ 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