Fix some issues in contrib/spi/refint.c.
check_foreign_key incorrectly used a single cache entry for its saved plans for a 'c' (cascade) trigger, although there are two different queries to execute depending on whether it fires for an update or a delete. This caused the wrong things to be done if both types of event occur in one session. (This was indeed visible in the triggers regression test, but apparently nobody ever questioned it.) To fix, add the operation type to the cache key. Its debug log output failed to distinguish update from delete events, too. Also, change the intended trigger usage from BEFORE ROW to AFTER ROW, and add checks insisting on that usage. BEFORE is really rather unsafe, since if there are other BEFORE triggers they might change or cancel the operation we are trying to check. AFTER triggers are the standard way to propagate changes to other rows, so we should follow that way here. In passing, remove a useless duplicate lookup of the cache entry. This code is mostly intended as a documentation example, so we won't consider a back-patch. Author: Dmitrii Bondar <d.bondar@postgrespro.ru> Reviewed-by: Paul Jungwirth <pj@illuminatedcomputing.com> Reviewed-by: Lilian Ontowhee <ontowhee@gmail.com> Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us> Discussion: https://postgr.es/m/79755a2b18ed4fe5e29da6a87a1e00d1@postgrespro.ru
This commit is contained in:
Tom Lane
parent
8e293e689b
commit
8cfbdf8f4d
@ -84,6 +84,10 @@ check_primary_key(PG_FUNCTION_ARGS)
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/* internal error */
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elog(ERROR, "check_primary_key: must be fired for row");
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if (!TRIGGER_FIRED_AFTER(trigdata->tg_event))
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/* internal error */
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elog(ERROR, "check_primary_key: must be fired by AFTER trigger");
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/* If INSERTion then must check Tuple to being inserted */
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if (TRIGGER_FIRED_BY_INSERT(trigdata->tg_event))
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tuple = trigdata->tg_trigtuple;
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@ -287,6 +291,10 @@ check_foreign_key(PG_FUNCTION_ARGS)
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/* internal error */
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elog(ERROR, "check_foreign_key: cannot process INSERT events");
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if (!TRIGGER_FIRED_AFTER(trigdata->tg_event))
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/* internal error */
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elog(ERROR, "check_foreign_key: must be fired by AFTER trigger");
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/* Have to check tg_trigtuple - tuple being deleted */
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trigtuple = trigdata->tg_trigtuple;
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@ -338,10 +346,10 @@ check_foreign_key(PG_FUNCTION_ARGS)
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kvals = (Datum *) palloc(nkeys * sizeof(Datum));
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/*
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* Construct ident string as TriggerName $ TriggeredRelationId and try to
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* find prepared execution plan(s).
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* Construct ident string as TriggerName $ TriggeredRelationId $
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* OperationType and try to find prepared execution plan(s).
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*/
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snprintf(ident, sizeof(ident), "%s$%u", trigger->tgname, rel->rd_id);
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snprintf(ident, sizeof(ident), "%s$%u$%c", trigger->tgname, rel->rd_id, is_update ? 'U' : 'D');
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plan = find_plan(ident, &FPlans, &nFPlans);
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/* if there is no plan(s) then allocate argtypes for preparation */
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@ -573,8 +581,6 @@ check_foreign_key(PG_FUNCTION_ARGS)
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relname = args[0];
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snprintf(ident, sizeof(ident), "%s$%u", trigger->tgname, rel->rd_id);
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plan = find_plan(ident, &FPlans, &nFPlans);
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ret = SPI_execp(plan->splan[r], kvals, NULL, tcount);
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/* we have no NULLs - so we pass ^^^^ here */
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@ -596,9 +602,15 @@ check_foreign_key(PG_FUNCTION_ARGS)
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else
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{
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#ifdef REFINT_VERBOSE
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const char *operation;
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if (action == 'c')
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operation = is_update ? "updated" : "deleted";
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else
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operation = "set to null";
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elog(NOTICE, "%s: " UINT64_FORMAT " tuple(s) of %s are %s",
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trigger->tgname, SPI_processed, relname,
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(action == 'c') ? "deleted" : "set to null");
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trigger->tgname, SPI_processed, relname, operation);
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#endif
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}
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args += nkeys + 1; /* to the next relation */
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@ -36,7 +36,7 @@
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<para>
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<function>check_primary_key()</function> checks the referencing table.
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To use, create a <literal>BEFORE INSERT OR UPDATE</literal> trigger using this
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To use, create an <literal>AFTER INSERT OR UPDATE</literal> trigger using this
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function on a table referencing another table. Specify as the trigger
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arguments: the referencing table's column name(s) which form the foreign
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key, the referenced table name, and the column names in the referenced table
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@ -46,7 +46,7 @@
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<para>
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<function>check_foreign_key()</function> checks the referenced table.
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To use, create a <literal>BEFORE DELETE OR UPDATE</literal> trigger using this
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To use, create an <literal>AFTER DELETE OR UPDATE</literal> trigger using this
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function on a table referenced by other table(s). Specify as the trigger
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arguments: the number of referencing tables for which the function has to
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perform checking, the action if a referencing key is found
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@ -60,6 +60,16 @@
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unique index.
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</para>
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<para>
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Note that if these triggers are executed from
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another <literal>BEFORE</literal> trigger, they can fail unexpectedly. For
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example, if a user inserts row1 and then the <literal>BEFORE</literal>
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trigger inserts row2 and calls a trigger with the
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<function>check_foreign_key()</function>,
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the <function>check_foreign_key()</function>
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function will not see row1 and will fail.
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</para>
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<para>
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There are examples in <filename>refint.example</filename>.
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</para>
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@ -46,12 +46,12 @@ create unique index pkeys_i on pkeys (pkey1, pkey2);
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-- (fkey3) --> fkeys2 (pkey23)
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--
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create trigger check_fkeys_pkey_exist
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before insert or update on fkeys
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after insert or update on fkeys
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for each row
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execute function
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check_primary_key ('fkey1', 'fkey2', 'pkeys', 'pkey1', 'pkey2');
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create trigger check_fkeys_pkey2_exist
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before insert or update on fkeys
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after insert or update on fkeys
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for each row
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execute function check_primary_key ('fkey3', 'fkeys2', 'pkey23');
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--
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@ -59,7 +59,7 @@ create trigger check_fkeys_pkey2_exist
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-- (fkey21, fkey22) --> pkeys (pkey1, pkey2)
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--
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create trigger check_fkeys2_pkey_exist
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before insert or update on fkeys2
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after insert or update on fkeys2
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for each row
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execute procedure
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check_primary_key ('fkey21', 'fkey22', 'pkeys', 'pkey1', 'pkey2');
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@ -74,7 +74,7 @@ COMMENT ON TRIGGER check_fkeys2_pkey_exist ON fkeys2 IS NULL;
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-- fkeys (fkey1, fkey2) and fkeys2 (fkey21, fkey22)
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--
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create trigger check_pkeys_fkey_cascade
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before delete or update on pkeys
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after delete or update on pkeys
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for each row
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execute procedure
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check_foreign_key (2, 'cascade', 'pkey1', 'pkey2',
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@ -85,7 +85,7 @@ create trigger check_pkeys_fkey_cascade
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-- fkeys (fkey3)
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--
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create trigger check_fkeys2_fkey_restrict
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before delete or update on fkeys2
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after delete or update on fkeys2
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for each row
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execute procedure check_foreign_key (1, 'restrict', 'pkey23', 'fkeys', 'fkey3');
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insert into fkeys2 values (10, '1', 1);
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@ -116,12 +116,11 @@ delete from pkeys where pkey1 = 40 and pkey2 = '4';
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NOTICE: check_pkeys_fkey_cascade: 1 tuple(s) of fkeys are deleted
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NOTICE: check_pkeys_fkey_cascade: 1 tuple(s) of fkeys2 are deleted
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update pkeys set pkey1 = 7, pkey2 = '70' where pkey1 = 50 and pkey2 = '5';
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NOTICE: check_pkeys_fkey_cascade: 1 tuple(s) of fkeys are deleted
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ERROR: "check_fkeys2_fkey_restrict": tuple is referenced in "fkeys"
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CONTEXT: SQL statement "delete from fkeys2 where fkey21 = $1 and fkey22 = $2 "
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NOTICE: check_pkeys_fkey_cascade: 1 tuple(s) of fkeys are updated
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NOTICE: check_pkeys_fkey_cascade: 1 tuple(s) of fkeys2 are updated
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update pkeys set pkey1 = 7, pkey2 = '70' where pkey1 = 10 and pkey2 = '1';
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NOTICE: check_pkeys_fkey_cascade: 1 tuple(s) of fkeys are deleted
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NOTICE: check_pkeys_fkey_cascade: 1 tuple(s) of fkeys2 are deleted
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ERROR: duplicate key value violates unique constraint "pkeys_i"
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DETAIL: Key (pkey1, pkey2)=(7, 70) already exists.
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SELECT trigger_name, event_manipulation, event_object_schema, event_object_table,
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action_order, action_condition, action_orientation, action_timing,
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action_reference_old_table, action_reference_new_table
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@ -130,16 +129,16 @@ SELECT trigger_name, event_manipulation, event_object_schema, event_object_table
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ORDER BY trigger_name COLLATE "C", 2;
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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
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----------------------------+--------------------+---------------------+--------------------+--------------+------------------+--------------------+---------------+----------------------------+----------------------------
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check_fkeys2_fkey_restrict | DELETE | public | fkeys2 | 1 | | ROW | BEFORE | |
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check_fkeys2_fkey_restrict | UPDATE | public | fkeys2 | 1 | | ROW | BEFORE | |
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check_fkeys2_pkey_exist | INSERT | public | fkeys2 | 1 | | ROW | BEFORE | |
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check_fkeys2_pkey_exist | UPDATE | public | fkeys2 | 2 | | ROW | BEFORE | |
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check_fkeys_pkey2_exist | INSERT | public | fkeys | 1 | | ROW | BEFORE | |
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check_fkeys_pkey2_exist | UPDATE | public | fkeys | 1 | | ROW | BEFORE | |
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check_fkeys_pkey_exist | INSERT | public | fkeys | 2 | | ROW | BEFORE | |
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check_fkeys_pkey_exist | UPDATE | public | fkeys | 2 | | ROW | BEFORE | |
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check_pkeys_fkey_cascade | DELETE | public | pkeys | 1 | | ROW | BEFORE | |
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check_pkeys_fkey_cascade | UPDATE | public | pkeys | 1 | | ROW | BEFORE | |
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check_fkeys2_fkey_restrict | DELETE | public | fkeys2 | 1 | | ROW | AFTER | |
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check_fkeys2_fkey_restrict | UPDATE | public | fkeys2 | 1 | | ROW | AFTER | |
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check_fkeys2_pkey_exist | INSERT | public | fkeys2 | 1 | | ROW | AFTER | |
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check_fkeys2_pkey_exist | UPDATE | public | fkeys2 | 2 | | ROW | AFTER | |
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check_fkeys_pkey2_exist | INSERT | public | fkeys | 1 | | ROW | AFTER | |
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check_fkeys_pkey2_exist | UPDATE | public | fkeys | 1 | | ROW | AFTER | |
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check_fkeys_pkey_exist | INSERT | public | fkeys | 2 | | ROW | AFTER | |
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check_fkeys_pkey_exist | UPDATE | public | fkeys | 2 | | ROW | AFTER | |
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check_pkeys_fkey_cascade | DELETE | public | pkeys | 1 | | ROW | AFTER | |
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check_pkeys_fkey_cascade | UPDATE | public | pkeys | 1 | | ROW | AFTER | |
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(10 rows)
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DROP TABLE pkeys;
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@ -57,13 +57,13 @@ create unique index pkeys_i on pkeys (pkey1, pkey2);
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-- (fkey3) --> fkeys2 (pkey23)
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--
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create trigger check_fkeys_pkey_exist
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before insert or update on fkeys
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after insert or update on fkeys
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for each row
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execute function
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check_primary_key ('fkey1', 'fkey2', 'pkeys', 'pkey1', 'pkey2');
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create trigger check_fkeys_pkey2_exist
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before insert or update on fkeys
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after insert or update on fkeys
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for each row
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execute function check_primary_key ('fkey3', 'fkeys2', 'pkey23');
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@ -72,7 +72,7 @@ create trigger check_fkeys_pkey2_exist
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-- (fkey21, fkey22) --> pkeys (pkey1, pkey2)
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--
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create trigger check_fkeys2_pkey_exist
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before insert or update on fkeys2
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after insert or update on fkeys2
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for each row
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execute procedure
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check_primary_key ('fkey21', 'fkey22', 'pkeys', 'pkey1', 'pkey2');
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@ -88,7 +88,7 @@ COMMENT ON TRIGGER check_fkeys2_pkey_exist ON fkeys2 IS NULL;
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-- fkeys (fkey1, fkey2) and fkeys2 (fkey21, fkey22)
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--
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create trigger check_pkeys_fkey_cascade
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before delete or update on pkeys
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after delete or update on pkeys
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for each row
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execute procedure
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check_foreign_key (2, 'cascade', 'pkey1', 'pkey2',
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@ -100,7 +100,7 @@ create trigger check_pkeys_fkey_cascade
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-- fkeys (fkey3)
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--
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create trigger check_fkeys2_fkey_restrict
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before delete or update on fkeys2
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after delete or update on fkeys2
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for each row
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execute procedure check_foreign_key (1, 'restrict', 'pkey23', 'fkeys', 'fkey3');
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