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Fix cross-leftover pollution in FOR PORTION OF insert triggers

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When we insert temporal leftovers after an UPDATE FOR PORTION OF, we
must make a new copy of the tuple before each insert.  Otherwise, if
an insert trigger assigns to attributes of NEW, the second leftover
sees those changes.

Author: Sergei Patiakin <sergei.patiakin@enterprisedb.com>
Reviewed-by: Paul A Jungwirth <pj@illuminatedcomputing.com>
Discussion: https://www.postgresql.org/message-id/flat/CANE55rCqcse_pwXBMWhbj3_7XROb8Dks6%3DOLFmKy3bO3zDsCsg%40mail.gmail.com
This commit is contained in:
Peter Eisentraut 2026-06-04 11:12:58 +02:00
parent 90354030b8
commit 993a7aa0e4
3 changed files with 88 additions and 0 deletions
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12
src/backend/executor/nodeModifyTable.c
View file

@ -1601,6 +1601,18 @@ ExecForPortionOfLeftovers(ModifyTableContext *context,
didInit = true;
}
else
{
/*
* Re-copy the original row into leftoverSlot because ExecInsert
* might pass leftoverSlot to BEFORE ROW INSERT triggers, which can
* modify the slot contents.
*/
if (map != NULL)
execute_attr_map_slot(map->attrMap, oldtupleSlot, leftoverSlot);
else
ExecForceStoreHeapTuple(oldtuple, leftoverSlot, false);
}
leftoverSlot->tts_values[forPortionOf->rangeVar->varattno - 1] = leftover;
leftoverSlot->tts_isnull[forPortionOf->rangeVar->varattno - 1] = false;

38
src/test/regress/expected/for_portion_of.out
View file

@ -1793,6 +1793,44 @@ SELECT * FROM for_portion_of_test WHERE id = '[4,5)' ORDER BY id, valid_at;
(3 rows)
DROP TRIGGER fpo_after_delete_row ON for_portion_of_test;
-- Test that a tuple-modifying BEFORE INSERT ROW trigger acts
-- consistently on both temporal leftovers.
-- When FOR PORTION OF splits a row into two leftovers, both triggers
-- should get the original row's values.
DROP TABLE for_portion_of_test;
CREATE TABLE for_portion_of_test (
id int,
valid_at daterange,
name text
);
CREATE FUNCTION fpo_append_name_suffix()
RETURNS TRIGGER LANGUAGE plpgsql AS
$$
BEGIN
NEW.name := NEW.name || '+insert';
RETURN NEW;
END;
$$;
CREATE TRIGGER fpo_before_insert_row
BEFORE INSERT ON for_portion_of_test
FOR EACH ROW EXECUTE PROCEDURE fpo_append_name_suffix();
INSERT INTO for_portion_of_test VALUES (1, '[2020-01-01,2020-12-31)', 'foo');
UPDATE for_portion_of_test
FOR PORTION OF valid_at FROM '2020-04-01' TO '2020-08-01'
SET name = 'bar'
WHERE id = 1;
-- Both leftovers should have the same name: 'foo+insert+insert'.
SELECT * FROM for_portion_of_test ORDER BY valid_at;
id | valid_at | name
----+-------------------------+-------------------
1 | [2020-01-01,2020-04-01) | foo+insert+insert
1 | [2020-04-01,2020-08-01) | bar
1 | [2020-08-01,2020-12-31) | foo+insert+insert
(3 rows)
DROP FUNCTION fpo_append_name_suffix CASCADE;
NOTICE: drop cascades to trigger fpo_before_insert_row on table for_portion_of_test
DROP TABLE for_portion_of_test;
-- Test with multiranges
CREATE TABLE for_portion_of_test2 (
id int4range NOT NULL,

38
src/test/regress/sql/for_portion_of.sql
View file

@ -1169,6 +1169,44 @@ SELECT * FROM for_portion_of_test WHERE id = '[4,5)' ORDER BY id, valid_at;
DROP TRIGGER fpo_after_delete_row ON for_portion_of_test;
-- Test that a tuple-modifying BEFORE INSERT ROW trigger acts
-- consistently on both temporal leftovers.
-- When FOR PORTION OF splits a row into two leftovers, both triggers
-- should get the original row's values.
DROP TABLE for_portion_of_test;
CREATE TABLE for_portion_of_test (
id int,
valid_at daterange,
name text
);
CREATE FUNCTION fpo_append_name_suffix()
RETURNS TRIGGER LANGUAGE plpgsql AS
$$
BEGIN
NEW.name := NEW.name || '+insert';
RETURN NEW;
END;
$$;
CREATE TRIGGER fpo_before_insert_row
BEFORE INSERT ON for_portion_of_test
FOR EACH ROW EXECUTE PROCEDURE fpo_append_name_suffix();
INSERT INTO for_portion_of_test VALUES (1, '[2020-01-01,2020-12-31)', 'foo');
UPDATE for_portion_of_test
FOR PORTION OF valid_at FROM '2020-04-01' TO '2020-08-01'
SET name = 'bar'
WHERE id = 1;
-- Both leftovers should have the same name: 'foo+insert+insert'.
SELECT * FROM for_portion_of_test ORDER BY valid_at;
DROP FUNCTION fpo_append_name_suffix CASCADE;
DROP TABLE for_portion_of_test;
-- Test with multiranges
CREATE TABLE for_portion_of_test2 (