[CF 5774] v5 - Extend skipping FK checks on replicas to include ADD FK and TRUNCATE

This branch was automatically generated by a robot using patches from an
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https://commitfest.postgresql.org/patch/5774

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Patch(es): https://www.postgresql.org/message-id/CAMT0RQS8ifBjeUyA9=an+=NahwtjUiH=HLq4fHc28-3kBZpHoQ@mail.gmail.com
Author(s): Hannu Krosing

Author: Commitfest Bot

src/backend/commands/tablecmds.c

@@ -2076,13 +2076,19 @@ ExecuteTruncateGuts(List *explicit_rels,
 	 * Check foreign key references.  In CASCADE mode, this should be
 	 * unnecessary since we just pulled in all the references; but as a
 	 * cross-check, do it anyway if in an Assert-enabled build.
+	 * 
+	 * Skip foreign key checks when `session_replication_role = replica` to
+	 * match the behaviour of disabling FK triggers in the same situation
 	 */
+	if (SessionReplicationRole != SESSION_REPLICATION_ROLE_REPLICA)
+	{
 #ifdef USE_ASSERT_CHECKING
-	heap_truncate_check_FKs(rels, false);
-#else
-	if (behavior == DROP_RESTRICT)
 		heap_truncate_check_FKs(rels, false);
+#else
+		if (behavior == DROP_RESTRICT)
+			heap_truncate_check_FKs(rels, false);
 #endif
+	}
 
 	/*
 	 * If we are asked to restart sequences, find all the sequences, lock them
@@ -6114,7 +6120,12 @@ ATRewriteTables(AlterTableStmt *parsetree, List **wqueue, LOCKMODE lockmode,
 	 * theoretically possible that we have changed both relations of the
 	 * foreign key, and we'd better have finished both rewrites before we try
 	 * to read the tables.
+	 * 
+	 * Skip the check when `session_replication_mode = replica` to save time 
+	 * and to match the FK trigger behaviour in the same situation 
 	 */
+	if (SessionReplicationRole != SESSION_REPLICATION_ROLE_REPLICA)
+	{
 	foreach(ltab, *wqueue)
 	{
 		AlteredTableInfo *tab = (AlteredTableInfo *) lfirst(ltab);
@@ -6159,6 +6170,7 @@ ATRewriteTables(AlterTableStmt *parsetree, List **wqueue, LOCKMODE lockmode,
 		if (rel)
 			table_close(rel, NoLock);
 	}
+	}
 
 	/* Finally, run any afterStmts that were queued up */
 	foreach(ltab, *wqueue)

src/test/regress/expected/foreign_key.out

@@ -3623,6 +3623,41 @@ ALTER TABLE fk_r DROP CONSTRAINT fk_r_p_id_p_jd_fkey_1;
 ERROR:  cannot drop inherited constraint "fk_r_p_id_p_jd_fkey_1" of relation "fk_r"
 ALTER TABLE fk_r_2 DROP CONSTRAINT fk_r_p_id_p_jd_fkey;
 ERROR:  cannot drop inherited constraint "fk_r_p_id_p_jd_fkey" of relation "fk_r_2"
+-- tests for SET session_replication_role = replica;
+RESET session_replication_role;
+-- disabling FK checks
+CREATE TABLE pkt(id int PRIMARY KEY);
+CREATE TABLE fkt(fk int REFERENCES pkt(id));
+INSERT INTO fkt VALUES(1); -- should fail
+ERROR:  insert or update on table "fkt" violates foreign key constraint "fkt_fk_fkey"
+DETAIL:  Key (fk)=(1) is not present in table "pkt".
+SET session_replication_role=replica;
+INSERT INTO fkt VALUES(1); -- should succeed now
+DROP TABLE fkt, pkt;
+RESET session_replication_role;
+-- skipping FK validation during ALTER TABLE ... ADD FOREIGN KEY
+CREATE TABLE pkt(id int PRIMARY KEY);
+CREATE TABLE fkt(fk int);
+INSERT INTO fkt VALUES(1);
+ALTER TABLE fkt ADD FOREIGN KEY (fk) REFERENCES pkt(id); -- should fail
+ERROR:  insert or update on table "fkt" violates foreign key constraint "fkt_fk_fkey"
+DETAIL:  Key (fk)=(1) is not present in table "pkt".
+SET session_replication_role=replica;
+ALTER TABLE fkt ADD FOREIGN KEY (fk) REFERENCES pkt(id); -- should succeed now
+DROP TABLE fkt, pkt;
+RESET session_replication_role;
+-- skipping FK existence checks during TRUNCATE
+CREATE TABLE pkt(id int PRIMARY KEY);
+CREATE TABLE fkt(fk int REFERENCES pkt(id));
+TRUNCATE pkt; -- should fail
+ERROR:  cannot truncate a table referenced in a foreign key constraint
+DETAIL:  Table "fkt" references "pkt".
+HINT:  Truncate table "fkt" at the same time, or use TRUNCATE ... CASCADE.
+SET session_replication_role=replica;
+TRUNCATE pkt; -- should succeed now
+DROP TABLE fkt, pkt;
+RESET session_replication_role;
+-- end of tests for SET session_replication_role = replica;
 SET client_min_messages TO warning;
 DROP SCHEMA fkpart12 CASCADE;
 RESET client_min_messages;

src/test/regress/sql/foreign_key.sql

@@ -2597,6 +2597,52 @@ ALTER TABLE fk_r_1 DROP CONSTRAINT fk_r_p_id_p_jd_fkey;
 ALTER TABLE fk_r DROP CONSTRAINT fk_r_p_id_p_jd_fkey_1;
 ALTER TABLE fk_r_2 DROP CONSTRAINT fk_r_p_id_p_jd_fkey;
 
+-- tests for SET session_replication_role = replica;
+
+RESET session_replication_role;
+
+-- disabling FK checks
+
+CREATE TABLE pkt(id int PRIMARY KEY);
+CREATE TABLE fkt(fk int REFERENCES pkt(id));
+
+INSERT INTO fkt VALUES(1); -- should fail
+
+SET session_replication_role=replica;
+INSERT INTO fkt VALUES(1); -- should succeed now
+
+DROP TABLE fkt, pkt;
+RESET session_replication_role;
+
+-- skipping FK validation during ALTER TABLE ... ADD FOREIGN KEY
+
+CREATE TABLE pkt(id int PRIMARY KEY);
+CREATE TABLE fkt(fk int);
+INSERT INTO fkt VALUES(1);
+
+ALTER TABLE fkt ADD FOREIGN KEY (fk) REFERENCES pkt(id); -- should fail
+
+SET session_replication_role=replica;
+ALTER TABLE fkt ADD FOREIGN KEY (fk) REFERENCES pkt(id); -- should succeed now
+
+DROP TABLE fkt, pkt;
+RESET session_replication_role;
+
+-- skipping FK existence checks during TRUNCATE
+
+CREATE TABLE pkt(id int PRIMARY KEY);
+CREATE TABLE fkt(fk int REFERENCES pkt(id));
+
+TRUNCATE pkt; -- should fail
+
+SET session_replication_role=replica;
+TRUNCATE pkt; -- should succeed now
+
+DROP TABLE fkt, pkt;
+RESET session_replication_role;
+
+-- end of tests for SET session_replication_role = replica;
+
 SET client_min_messages TO warning;
 DROP SCHEMA fkpart12 CASCADE;
 RESET client_min_messages;