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This event takes place just before ddl_command_end, and is fired if and only if at least one object has been dropped by the command. (For instance, DROP TABLE IF EXISTS of a table that does not in fact exist will not lead to such a trigger firing). Commands that drop multiple objects (such as DROP SCHEMA or DROP OWNED BY) will cause a single event to fire. Some firings might be surprising, such as ALTER TABLE DROP COLUMN. The trigger is fired after the drop has taken place, because that has been deemed the safest design, to avoid exposing possibly-inconsistent internal state (system catalogs as well as current transaction) to the user function code. This means that careful tracking of object identification is required during the object removal phase. Like other currently existing events, there is support for tag filtering. To support the new event, add a new pg_event_trigger_dropped_objects() set-returning function, which returns a set of rows comprising the objects affected by the command. This is to be used within the user function code, and is mostly modelled after the recently introduced pg_identify_object() function. Catalog version bumped due to the new function. Dimitri Fontaine and Álvaro Herrera Review by Robert Haas, Tom Lane
208 lines
6.8 KiB
PL/PgSQL
208 lines
6.8 KiB
PL/PgSQL
-- should fail, return type mismatch
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create event trigger regress_event_trigger
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on ddl_command_start
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execute procedure pg_backend_pid();
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-- OK
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create function test_event_trigger() returns event_trigger as $$
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BEGIN
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RAISE NOTICE 'test_event_trigger: % %', tg_event, tg_tag;
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END
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$$ language plpgsql;
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-- should fail, no elephant_bootstrap entry point
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create event trigger regress_event_trigger on elephant_bootstrap
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execute procedure test_event_trigger();
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-- OK
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create event trigger regress_event_trigger on ddl_command_start
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execute procedure test_event_trigger();
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-- OK
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create event trigger regress_event_trigger_end on ddl_command_end
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execute procedure test_event_trigger();
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-- should fail, food is not a valid filter variable
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create event trigger regress_event_trigger2 on ddl_command_start
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when food in ('sandwhich')
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execute procedure test_event_trigger();
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-- should fail, sandwhich is not a valid command tag
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create event trigger regress_event_trigger2 on ddl_command_start
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when tag in ('sandwhich')
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execute procedure test_event_trigger();
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-- should fail, create skunkcabbage is not a valid comand tag
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create event trigger regress_event_trigger2 on ddl_command_start
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when tag in ('create table', 'create skunkcabbage')
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execute procedure test_event_trigger();
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-- should fail, can't have event triggers on event triggers
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create event trigger regress_event_trigger2 on ddl_command_start
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when tag in ('DROP EVENT TRIGGER')
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execute procedure test_event_trigger();
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-- should fail, can't have same filter variable twice
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create event trigger regress_event_trigger2 on ddl_command_start
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when tag in ('create table') and tag in ('CREATE FUNCTION')
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execute procedure test_event_trigger();
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-- OK
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create event trigger regress_event_trigger2 on ddl_command_start
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when tag in ('create table', 'CREATE FUNCTION')
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execute procedure test_event_trigger();
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-- OK
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comment on event trigger regress_event_trigger is 'test comment';
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-- should fail, event triggers are not schema objects
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comment on event trigger wrong.regress_event_trigger is 'test comment';
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-- drop as non-superuser should fail
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create role regression_bob;
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set role regression_bob;
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create event trigger regress_event_trigger_noperms on ddl_command_start
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execute procedure test_event_trigger();
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reset role;
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-- all OK
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alter event trigger regress_event_trigger enable replica;
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alter event trigger regress_event_trigger enable always;
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alter event trigger regress_event_trigger enable;
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alter event trigger regress_event_trigger disable;
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-- regress_event_trigger2 and regress_event_trigger_end should fire, but not
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-- regress_event_trigger
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create table event_trigger_fire1 (a int);
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-- regress_event_trigger_end should fire here
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drop table event_trigger_fire1;
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-- alter owner to non-superuser should fail
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alter event trigger regress_event_trigger owner to regression_bob;
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-- alter owner to superuser should work
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alter role regression_bob superuser;
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alter event trigger regress_event_trigger owner to regression_bob;
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-- should fail, name collision
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alter event trigger regress_event_trigger rename to regress_event_trigger2;
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-- OK
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alter event trigger regress_event_trigger rename to regress_event_trigger3;
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-- should fail, doesn't exist any more
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drop event trigger regress_event_trigger;
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-- should fail, regression_bob owns regress_event_trigger2/3
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drop role regression_bob;
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-- cleanup before next test
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-- these are all OK; the second one should emit a NOTICE
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drop event trigger if exists regress_event_trigger2;
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drop event trigger if exists regress_event_trigger2;
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drop event trigger regress_event_trigger3;
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drop event trigger regress_event_trigger_end;
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-- test support for dropped objects
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CREATE SCHEMA schema_one authorization regression_bob;
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CREATE SCHEMA schema_two authorization regression_bob;
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CREATE SCHEMA audit_tbls authorization regression_bob;
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SET SESSION AUTHORIZATION regression_bob;
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CREATE TABLE schema_one.table_one(a int);
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CREATE TABLE schema_one."table two"(a int);
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CREATE TABLE schema_one.table_three(a int);
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CREATE TABLE audit_tbls.schema_one_table_two(the_value text);
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CREATE TABLE schema_two.table_two(a int);
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CREATE TABLE schema_two.table_three(a int, b text);
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CREATE TABLE audit_tbls.schema_two_table_three(the_value text);
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CREATE OR REPLACE FUNCTION schema_two.add(int, int) RETURNS int LANGUAGE plpgsql
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CALLED ON NULL INPUT
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AS $$ BEGIN RETURN coalesce($1,0) + coalesce($2,0); END; $$;
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CREATE AGGREGATE schema_two.newton
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(BASETYPE = int, SFUNC = schema_two.add, STYPE = int);
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RESET SESSION AUTHORIZATION;
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CREATE TABLE undroppable_objs (
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object_type text,
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object_identity text
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);
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INSERT INTO undroppable_objs VALUES
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('table', 'schema_one.table_three'),
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('table', 'audit_tbls.schema_two_table_three');
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CREATE TABLE dropped_objects (
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type text,
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schema text,
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object text
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);
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-- This tests errors raised within event triggers; the one in audit_tbls
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-- uses 2nd-level recursive invocation via test_evtrig_dropped_objects().
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CREATE OR REPLACE FUNCTION undroppable() RETURNS event_trigger
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LANGUAGE plpgsql AS $$
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DECLARE
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obj record;
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BEGIN
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PERFORM 1 FROM pg_tables WHERE tablename = 'undroppable_objs';
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IF NOT FOUND THEN
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RAISE NOTICE 'table undroppable_objs not found, skipping';
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RETURN;
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END IF;
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FOR obj IN
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SELECT * FROM pg_event_trigger_dropped_objects() JOIN
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undroppable_objs USING (object_type, object_identity)
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LOOP
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RAISE EXCEPTION 'object % of type % cannot be dropped',
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obj.object_identity, obj.object_type;
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END LOOP;
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END;
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$$;
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CREATE EVENT TRIGGER undroppable ON sql_drop
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EXECUTE PROCEDURE undroppable();
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CREATE OR REPLACE FUNCTION test_evtrig_dropped_objects() RETURNS event_trigger
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LANGUAGE plpgsql AS $$
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DECLARE
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obj record;
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BEGIN
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FOR obj IN SELECT * FROM pg_event_trigger_dropped_objects()
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LOOP
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IF obj.object_type = 'table' THEN
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EXECUTE format('DROP TABLE IF EXISTS audit_tbls.%I',
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format('%s_%s', obj.schema_name, obj.object_name));
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END IF;
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INSERT INTO dropped_objects
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(type, schema, object) VALUES
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(obj.object_type, obj.schema_name, obj.object_identity);
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END LOOP;
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END
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$$;
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CREATE EVENT TRIGGER regress_event_trigger_drop_objects ON sql_drop
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WHEN TAG IN ('drop table', 'drop function', 'drop view',
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'drop owned', 'drop schema', 'alter table')
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EXECUTE PROCEDURE test_evtrig_dropped_objects();
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ALTER TABLE schema_one.table_one DROP COLUMN a;
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DROP SCHEMA schema_one, schema_two CASCADE;
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DELETE FROM undroppable_objs WHERE object_identity = 'audit_tbls.schema_two_table_three';
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DROP SCHEMA schema_one, schema_two CASCADE;
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DELETE FROM undroppable_objs WHERE object_identity = 'schema_one.table_three';
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DROP SCHEMA schema_one, schema_two CASCADE;
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SELECT * FROM dropped_objects WHERE schema IS NULL OR schema <> 'pg_toast';
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DROP OWNED BY regression_bob;
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SELECT * FROM dropped_objects WHERE type = 'schema';
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DROP ROLE regression_bob;
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DROP EVENT TRIGGER regress_event_trigger_drop_objects;
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DROP EVENT TRIGGER undroppable;
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