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Fix MERGE command tag for actions blocked by BEFORE ROW triggers.

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This ensures that the row count in the command tag for a MERGE is
correctly computed in the case where UPDATEs or DELETEs are skipped
due to a BEFORE ROW trigger returning NULL (the INSERT case was
already handled correctly by ExecMergeNotMatched() calling
ExecInsert()).

Back-patch to v15, where MERGE was introduced.

Discussion: https://postgr.es/m/CAEZATCU8XEmR0JWKDtyb7iZ%3DqCffxS9uyJt0iOZ4TV4RT%2Bow1w%40mail.gmail.com
This commit is contained in:
Dean Rasheed 2023-03-13 11:09:39 +00:00
parent 9321c79c86
commit 7b14e20b12
3 changed files with 34 additions and 4 deletions
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10
src/backend/executor/nodeModifyTable.c
View File

@ -2883,8 +2883,9 @@ lmerge_matched:
if (!ExecUpdatePrologue(context, resultRelInfo,
tupleid, NULL, newslot, &result))
{
/* Blocked by trigger, or concurrent update/delete */
break;
if (result == TM_Ok)
return true; /* "do nothing" */
break; /* concurrent update/delete */
}
result = ExecUpdateAct(context, resultRelInfo, tupleid, NULL,
newslot, false, &updateCxt);
@ -2901,8 +2902,9 @@ lmerge_matched:
if (!ExecDeletePrologue(context, resultRelInfo, tupleid,
NULL, NULL, &result))
{
/* Blocked by trigger, or concurrent update/delete */
break;
if (result == TM_Ok)
return true; /* "do nothing" */
break; /* concurrent update/delete */
}
result = ExecDeleteAct(context, resultRelInfo, tupleid, false);
if (result == TM_Ok)

15
src/test/regress/expected/merge.out
View File

@ -942,12 +942,25 @@ SELECT * FROM target full outer join source on (sid = tid);
create trigger merge_skip BEFORE INSERT OR UPDATE or DELETE
ON target FOR EACH ROW EXECUTE FUNCTION skip_merge_op();
DO $$
DECLARE
result integer;
BEGIN
MERGE INTO target t
USING source AS s
ON t.tid = s.sid
WHEN MATCHED AND s.sid = 3 THEN UPDATE SET balance = t.balance + s.delta
WHEN MATCHED THEN DELETE
WHEN NOT MATCHED THEN INSERT VALUES (sid, delta);
IF FOUND THEN
RAISE NOTICE 'Found';
ELSE
RAISE NOTICE 'Not found';
END IF;
GET DIAGNOSTICS result := ROW_COUNT;
RAISE NOTICE 'ROW_COUNT = %', result;
END;
$$;
NOTICE: BEFORE INSERT STATEMENT trigger
NOTICE: BEFORE UPDATE STATEMENT trigger
NOTICE: BEFORE DELETE STATEMENT trigger
@ -957,6 +970,8 @@ NOTICE: BEFORE INSERT ROW trigger row: (4,40)
NOTICE: AFTER DELETE STATEMENT trigger
NOTICE: AFTER UPDATE STATEMENT trigger
NOTICE: AFTER INSERT STATEMENT trigger
NOTICE: Not found
NOTICE: ROW_COUNT = 0
SELECT * FROM target FULL OUTER JOIN source ON (sid = tid);
tid | balance | sid | delta
-----+---------+-----+-------

13
src/test/regress/sql/merge.sql
View File

@ -636,12 +636,25 @@ $$;
SELECT * FROM target full outer join source on (sid = tid);
create trigger merge_skip BEFORE INSERT OR UPDATE or DELETE
ON target FOR EACH ROW EXECUTE FUNCTION skip_merge_op();
DO $$
DECLARE
result integer;
BEGIN
MERGE INTO target t
USING source AS s
ON t.tid = s.sid
WHEN MATCHED AND s.sid = 3 THEN UPDATE SET balance = t.balance + s.delta
WHEN MATCHED THEN DELETE
WHEN NOT MATCHED THEN INSERT VALUES (sid, delta);
IF FOUND THEN
RAISE NOTICE 'Found';
ELSE
RAISE NOTICE 'Not found';
END IF;
GET DIAGNOSTICS result := ROW_COUNT;
RAISE NOTICE 'ROW_COUNT = %', result;
END;
$$;
SELECT * FROM target FULL OUTER JOIN source ON (sid = tid);
DROP TRIGGER merge_skip ON target;
DROP FUNCTION skip_merge_op();