0001-Consistent-trigger-behavior-between-multiple-tempora.patch

From 19d9e8114e7439e7c784a72d64dc07bb85ae2415 Mon Sep 17 00:00:00 2001
From: Sergei Patiakin <sergei.patiakin@enterprisedb.com>
Date: Wed, 8 Apr 2026 14:46:09 +0200
Subject: [PATCH] Consistent trigger behavior between multiple temporal
 leftovers

Avoid leaking modifications from one temporal leftover's
BEFORE INSERT ROW trigger to another temporal leftover.
---
 src/backend/executor/nodeModifyTable.c       | 13 +++++++
 src/test/regress/expected/for_portion_of.out | 37 ++++++++++++++++++++
 src/test/regress/sql/for_portion_of.sql      | 37 ++++++++++++++++++++
 3 files changed, 87 insertions(+)

diff --git a/src/backend/executor/nodeModifyTable.c b/src/backend/executor/nodeModifyTable.c
index ef2a6bc6e9d..7d77d0a511c 100644
--- a/src/backend/executor/nodeModifyTable.c
+++ b/src/backend/executor/nodeModifyTable.c
@@ -1584,6 +1584,19 @@ ExecForPortionOfLeftovers(ModifyTableContext *context,
 
 			didInit = true;
 		}
+		else
+		{
+			/*
+			 * Re-copy the original row into leftoverSlot because
+			 * ExecInsert may pass leftoverSlot to BEFORE 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;
diff --git a/src/test/regress/expected/for_portion_of.out b/src/test/regress/expected/for_portion_of.out
index 31f772c723d..0d21944181c 100644
--- a/src/test/regress/expected/for_portion_of.out
+++ b/src/test/regress/expected/for_portion_of.out
@@ -1793,6 +1793,43 @@ 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
 -- Test with multiranges
 CREATE TABLE for_portion_of_test2 (
   id int4range NOT NULL,
diff --git a/src/test/regress/sql/for_portion_of.sql b/src/test/regress/sql/for_portion_of.sql
index d4062acf1d1..a7dec60e364 100644
--- a/src/test/regress/sql/for_portion_of.sql
+++ b/src/test/regress/sql/for_portion_of.sql
@@ -1169,6 +1169,43 @@ 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;
+
 -- Test with multiranges
 
 CREATE TABLE for_portion_of_test2 (
-- 
2.47.3