[CF 5577] v6 - Invalid cached plan in check_foreign_key; cascade update in check_primary_key; refint.c

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https://commitfest.postgresql.org/patch/5577

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Patch(es): https://www.postgresql.org/message-id/[email protected]
Author(s): Dmitrii Bondar

Author: Commitfest Bot

contrib/spi/refint.c

@@ -84,6 +84,10 @@ check_primary_key(PG_FUNCTION_ARGS)
 		/* internal error */
 		elog(ERROR, "check_primary_key: must be fired for row");
 
+	if (!TRIGGER_FIRED_AFTER(trigdata->tg_event))
+		/* internal error */
+		elog(ERROR, "check_primary_key: must be fired by AFTER trigger");
+
 	/* If INSERTion then must check Tuple to being inserted */
 	if (TRIGGER_FIRED_BY_INSERT(trigdata->tg_event))
 		tuple = trigdata->tg_trigtuple;
@@ -267,7 +271,6 @@ check_foreign_key(PG_FUNCTION_ARGS)
 #ifdef DEBUG_QUERY
 	elog(DEBUG4, "check_foreign_key: Enter Function");
 #endif
-
 	/*
 	 * Some checks first...
 	 */
@@ -287,6 +290,10 @@ check_foreign_key(PG_FUNCTION_ARGS)
 		/* internal error */
 		elog(ERROR, "check_foreign_key: cannot process INSERT events");
 
+	if (!TRIGGER_FIRED_AFTER(trigdata->tg_event))
+		/* internal error */
+		elog(ERROR, "check_foreign_key: must be fired by AFTER trigger");
+
 	/* Have to check tg_trigtuple - tuple being deleted */
 	trigtuple = trigdata->tg_trigtuple;
 
@@ -338,10 +345,10 @@ check_foreign_key(PG_FUNCTION_ARGS)
 	kvals = (Datum *) palloc(nkeys * sizeof(Datum));
 
 	/*
-	 * Construct ident string as TriggerName $ TriggeredRelationId and try to
-	 * find prepared execution plan(s).
+	 * Construct ident string as TriggerName $ TriggeredRelationId $ OperationType
+	 * and try to find prepared execution plan(s).
 	 */
-	snprintf(ident, sizeof(ident), "%s$%u", trigger->tgname, rel->rd_id);
+	snprintf(ident, sizeof(ident), "%s$%u$%c", trigger->tgname, rel->rd_id, is_update ? 'U' : 'D');
 	plan = find_plan(ident, &FPlans, &nFPlans);
 
 	/* if there is no plan(s) then allocate argtypes for preparation */
@@ -573,7 +580,6 @@ check_foreign_key(PG_FUNCTION_ARGS)
 
 		relname = args[0];
 
-		snprintf(ident, sizeof(ident), "%s$%u", trigger->tgname, rel->rd_id);
 		plan = find_plan(ident, &FPlans, &nFPlans);
 		ret = SPI_execp(plan->splan[r], kvals, NULL, tcount);
 		/* we have no NULLs - so we pass   ^^^^  here */
@@ -596,9 +602,15 @@ check_foreign_key(PG_FUNCTION_ARGS)
 		else
 		{
 #ifdef REFINT_VERBOSE
+			const char* operation;
+
+			if (action == 'c')
+				operation = is_update ? "updated" : "deleted";
+			else
+				operation = "set to null";
+
 			elog(NOTICE, "%s: " UINT64_FORMAT " tuple(s) of %s are %s",
-				 trigger->tgname, SPI_processed, relname,
-				 (action == 'c') ? "deleted" : "set to null");
+				 trigger->tgname, SPI_processed, relname, operation);
 #endif
 		}
 		args += nkeys + 1;		/* to the next relation */

doc/src/sgml/contrib-spi.sgml

@@ -36,7 +36,7 @@
 
   <para>
    <function>check_primary_key()</function> checks the referencing table.
-   To use, create a <literal>BEFORE INSERT OR UPDATE</literal> trigger using this
+   To use, create an <literal>AFTER INSERT OR UPDATE</literal> trigger using this
    function on a table referencing another table. Specify as the trigger
    arguments: the referencing table's column name(s) which form the foreign
    key, the referenced table name, and the column names in the referenced table
@@ -46,7 +46,7 @@
 
   <para>
    <function>check_foreign_key()</function> checks the referenced table.
-   To use, create a <literal>BEFORE DELETE OR UPDATE</literal> trigger using this
+   To use, create an <literal>AFTER DELETE OR UPDATE</literal> trigger using this
    function on a table referenced by other table(s).  Specify as the trigger
    arguments: the number of referencing tables for which the function has to
    perform checking, the action if a referencing key is found
@@ -63,6 +63,14 @@
   <para>
    There are examples in <filename>refint.example</filename>.
   </para>
+
+  <para>
+   Note that if these triggers are executed from another <literal>BEFORE</literal>
+   trigger, they can fail unexpectedly. For example, if a user inserts row1 and then
+   the <literal>BEFORE</literal> trigger inserts row2 and calls a trigger with the
+   <function>check_foreign_key()</function>, the <function>check_foreign_key()</function>
+   function will not see row1 and will fail.
+  </para>
  </sect2>
 
  <sect2 id="contrib-spi-autoinc">

src/test/regress/expected/triggers.out

@@ -46,20 +46,20 @@ create unique index pkeys_i on pkeys (pkey1, pkey2);
 -- 	(fkey3)		--> fkeys2 (pkey23)
 --
 create trigger check_fkeys_pkey_exist
-	before insert or update on fkeys
+	after insert or update on fkeys
 	for each row
 	execute function
 	check_primary_key ('fkey1', 'fkey2', 'pkeys', 'pkey1', 'pkey2');
 create trigger check_fkeys_pkey2_exist
-	before insert or update on fkeys
+	after insert or update on fkeys
 	for each row
 	execute function check_primary_key ('fkey3', 'fkeys2', 'pkey23');
 --
 -- For fkeys2:
 -- 	(fkey21, fkey22)	--> pkeys (pkey1, pkey2)
 --
 create trigger check_fkeys2_pkey_exist
-	before insert or update on fkeys2
+	after insert or update on fkeys2
 	for each row
 	execute procedure
 	check_primary_key ('fkey21', 'fkey22', 'pkeys', 'pkey1', 'pkey2');
@@ -74,7 +74,7 @@ COMMENT ON TRIGGER check_fkeys2_pkey_exist ON fkeys2 IS NULL;
 -- 		fkeys (fkey1, fkey2) and fkeys2 (fkey21, fkey22)
 --
 create trigger check_pkeys_fkey_cascade
-	before delete or update on pkeys
+	after delete or update on pkeys
 	for each row
 	execute procedure
 	check_foreign_key (2, 'cascade', 'pkey1', 'pkey2',
@@ -85,9 +85,27 @@ create trigger check_pkeys_fkey_cascade
 -- 		fkeys (fkey3)
 --
 create trigger check_fkeys2_fkey_restrict
-	before delete or update on fkeys2
+	after delete or update on fkeys2
 	for each row
 	execute procedure check_foreign_key (1, 'restrict', 'pkey23', 'fkeys', 'fkey3');
+-- BEFORE triggers must raise an error
+create trigger check_fkeys2_pkey_exist_before
+	before insert or update on fkeys2
+	for each row
+	execute procedure
+	check_primary_key ('fkey21', 'fkey22', 'pkeys', 'pkey1', 'pkey2');
+create trigger check_pkeys_fkey_cascade_before
+	before delete or update on pkeys
+	for each row
+	execute procedure
+	check_foreign_key (2, 'cascade', 'pkey1', 'pkey2',
+	'fkeys', 'fkey1', 'fkey2', 'fkeys2', 'fkey21', 'fkey22');
+update pkeys set pkey1 = 7, pkey2 = '70' where pkey1 = 10 and pkey2 = '1';
+ERROR:  check_foreign_key: must be fired by AFTER trigger
+insert into fkeys2 values (10, '1', 1);
+ERROR:  check_primary_key: must be fired by AFTER trigger
+drop trigger check_fkeys2_pkey_exist_before on fkeys2;
+drop trigger check_pkeys_fkey_cascade_before on pkeys;
 insert into fkeys2 values (10, '1', 1);
 insert into fkeys2 values (30, '3', 2);
 insert into fkeys2 values (40, '4', 5);
@@ -116,12 +134,11 @@ delete from pkeys where pkey1 = 40 and pkey2 = '4';
 NOTICE:  check_pkeys_fkey_cascade: 1 tuple(s) of fkeys are deleted
 NOTICE:  check_pkeys_fkey_cascade: 1 tuple(s) of fkeys2 are deleted
 update pkeys set pkey1 = 7, pkey2 = '70' where pkey1 = 50 and pkey2 = '5';
-NOTICE:  check_pkeys_fkey_cascade: 1 tuple(s) of fkeys are deleted
-ERROR:  "check_fkeys2_fkey_restrict": tuple is referenced in "fkeys"
-CONTEXT:  SQL statement "delete from fkeys2 where fkey21 = $1 and fkey22 = $2 "
+NOTICE:  check_pkeys_fkey_cascade: 1 tuple(s) of fkeys are updated
+NOTICE:  check_pkeys_fkey_cascade: 1 tuple(s) of fkeys2 are updated
 update pkeys set pkey1 = 7, pkey2 = '70' where pkey1 = 10 and pkey2 = '1';
-NOTICE:  check_pkeys_fkey_cascade: 1 tuple(s) of fkeys are deleted
-NOTICE:  check_pkeys_fkey_cascade: 1 tuple(s) of fkeys2 are deleted
+ERROR:  duplicate key value violates unique constraint "pkeys_i"
+DETAIL:  Key (pkey1, pkey2)=(7, 70) already exists.
 SELECT trigger_name, event_manipulation, event_object_schema, event_object_table,
        action_order, action_condition, action_orientation, action_timing,
        action_reference_old_table, action_reference_new_table
@@ -130,16 +147,16 @@ SELECT trigger_name, event_manipulation, event_object_schema, event_object_table
   ORDER BY trigger_name COLLATE "C", 2;
         trigger_name        | event_manipulation | event_object_schema | event_object_table | action_order | action_condition | action_orientation | action_timing | action_reference_old_table | action_reference_new_table 
 ----------------------------+--------------------+---------------------+--------------------+--------------+------------------+--------------------+---------------+----------------------------+----------------------------
- check_fkeys2_fkey_restrict | DELETE             | public              | fkeys2             |            1 |                  | ROW                | BEFORE        |                            | 
- check_fkeys2_fkey_restrict | UPDATE             | public              | fkeys2             |            1 |                  | ROW                | BEFORE        |                            | 
- check_fkeys2_pkey_exist    | INSERT             | public              | fkeys2             |            1 |                  | ROW                | BEFORE        |                            | 
- check_fkeys2_pkey_exist    | UPDATE             | public              | fkeys2             |            2 |                  | ROW                | BEFORE        |                            | 
- check_fkeys_pkey2_exist    | INSERT             | public              | fkeys              |            1 |                  | ROW                | BEFORE        |                            | 
- check_fkeys_pkey2_exist    | UPDATE             | public              | fkeys              |            1 |                  | ROW                | BEFORE        |                            | 
- check_fkeys_pkey_exist     | INSERT             | public              | fkeys              |            2 |                  | ROW                | BEFORE        |                            | 
- check_fkeys_pkey_exist     | UPDATE             | public              | fkeys              |            2 |                  | ROW                | BEFORE        |                            | 
- check_pkeys_fkey_cascade   | DELETE             | public              | pkeys              |            1 |                  | ROW                | BEFORE        |                            | 
- check_pkeys_fkey_cascade   | UPDATE             | public              | pkeys              |            1 |                  | ROW                | BEFORE        |                            | 
+ check_fkeys2_fkey_restrict | DELETE             | public              | fkeys2             |            1 |                  | ROW                | AFTER         |                            | 
+ check_fkeys2_fkey_restrict | UPDATE             | public              | fkeys2             |            1 |                  | ROW                | AFTER         |                            | 
+ check_fkeys2_pkey_exist    | INSERT             | public              | fkeys2             |            1 |                  | ROW                | AFTER         |                            | 
+ check_fkeys2_pkey_exist    | UPDATE             | public              | fkeys2             |            2 |                  | ROW                | AFTER         |                            | 
+ check_fkeys_pkey2_exist    | INSERT             | public              | fkeys              |            1 |                  | ROW                | AFTER         |                            | 
+ check_fkeys_pkey2_exist    | UPDATE             | public              | fkeys              |            1 |                  | ROW                | AFTER         |                            | 
+ check_fkeys_pkey_exist     | INSERT             | public              | fkeys              |            2 |                  | ROW                | AFTER         |                            | 
+ check_fkeys_pkey_exist     | UPDATE             | public              | fkeys              |            2 |                  | ROW                | AFTER         |                            | 
+ check_pkeys_fkey_cascade   | DELETE             | public              | pkeys              |            1 |                  | ROW                | AFTER         |                            | 
+ check_pkeys_fkey_cascade   | UPDATE             | public              | pkeys              |            1 |                  | ROW                | AFTER         |                            | 
 (10 rows)
 
 DROP TABLE pkeys;

src/test/regress/sql/triggers.sql

@@ -57,13 +57,13 @@ create unique index pkeys_i on pkeys (pkey1, pkey2);
 -- 	(fkey3)		--> fkeys2 (pkey23)
 --
 create trigger check_fkeys_pkey_exist
-	before insert or update on fkeys
+	after insert or update on fkeys
 	for each row
 	execute function
 	check_primary_key ('fkey1', 'fkey2', 'pkeys', 'pkey1', 'pkey2');
 
 create trigger check_fkeys_pkey2_exist
-	before insert or update on fkeys
+	after insert or update on fkeys
 	for each row
 	execute function check_primary_key ('fkey3', 'fkeys2', 'pkey23');
 
@@ -72,7 +72,7 @@ create trigger check_fkeys_pkey2_exist
 -- 	(fkey21, fkey22)	--> pkeys (pkey1, pkey2)
 --
 create trigger check_fkeys2_pkey_exist
-	before insert or update on fkeys2
+	after insert or update on fkeys2
 	for each row
 	execute procedure
 	check_primary_key ('fkey21', 'fkey22', 'pkeys', 'pkey1', 'pkey2');
@@ -88,7 +88,7 @@ COMMENT ON TRIGGER check_fkeys2_pkey_exist ON fkeys2 IS NULL;
 -- 		fkeys (fkey1, fkey2) and fkeys2 (fkey21, fkey22)
 --
 create trigger check_pkeys_fkey_cascade
-	before delete or update on pkeys
+	after delete or update on pkeys
 	for each row
 	execute procedure
 	check_foreign_key (2, 'cascade', 'pkey1', 'pkey2',
@@ -100,10 +100,30 @@ create trigger check_pkeys_fkey_cascade
 -- 		fkeys (fkey3)
 --
 create trigger check_fkeys2_fkey_restrict
-	before delete or update on fkeys2
+	after delete or update on fkeys2
 	for each row
 	execute procedure check_foreign_key (1, 'restrict', 'pkey23', 'fkeys', 'fkey3');
 
+-- BEFORE triggers must raise an error
+create trigger check_fkeys2_pkey_exist_before
+	before insert or update on fkeys2
+	for each row
+	execute procedure
+	check_primary_key ('fkey21', 'fkey22', 'pkeys', 'pkey1', 'pkey2');
+
+create trigger check_pkeys_fkey_cascade_before
+	before delete or update on pkeys
+	for each row
+	execute procedure
+	check_foreign_key (2, 'cascade', 'pkey1', 'pkey2',
+	'fkeys', 'fkey1', 'fkey2', 'fkeys2', 'fkey21', 'fkey22');
+
+update pkeys set pkey1 = 7, pkey2 = '70' where pkey1 = 10 and pkey2 = '1';
+insert into fkeys2 values (10, '1', 1);
+
+drop trigger check_fkeys2_pkey_exist_before on fkeys2;
+drop trigger check_pkeys_fkey_cascade_before on pkeys;
+
 insert into fkeys2 values (10, '1', 1);
 insert into fkeys2 values (30, '3', 2);
 insert into fkeys2 values (40, '4', 5);