Hello,
It seams that tiggers don't fire on subscriber's tables during logical replication. Is it a bug?


#
# publisher: simple table and publication
#

postgres@publisher=# SELECT version();
version
-------------------------------------------------------------------------------------------------------------------
PostgreSQL 10devel on x86_64-pc-linux-gnu, compiled by gcc (Ubuntu 5.4.0-6ubuntu1~16.04.4) 5.4.0 20160609, 64-bit
(1 row)

postgres@publisher=# CREATE TABLE t(n integer PRIMARY KEY);

postgres@publisher=# CREATE PUBLICATION testpub FOR TABLE t;

#
# subscriber: the same table, triggers to write some information into log table, and subscription
#

postgres@subscriber=# CREATE TABLE t(n integer PRIMARY KEY);

postgres@subscriber=# CREATE TABLE log(tg_table_name text, tg_when text, tg_op text, tg_level text, tg_str text);

postgres@subscriber=# CREATE OR REPLACE FUNCTION public.describe()
 RETURNS trigger
 LANGUAGE plpgsql
AS $function$
DECLARE
    rec record;
    str text := '';
BEGIN
    IF TG_LEVEL = 'ROW' THEN
        CASE TG_OP
            WHEN 'DELETE' THEN rec := OLD; str := OLD::text;
            WHEN 'UPDATE' THEN rec := NEW; str := OLD || ' -> ' || NEW;
            WHEN 'INSERT' THEN rec := NEW; str := NEW::text;
        END CASE;
    END IF;
INSERT INTO log(tg_table_name, tg_when, tg_op, tg_level, tg_str) VALUES (TG_TABLE_NAME, TG_WHEN, TG_OP, TG_LEVEL, str);
    RETURN rec;
END;
$function$;

postgres@subscriber=# CREATE TRIGGER t_before_row BEFORE INSERT OR UPDATE OR DELETE ON t FOR EACH ROW EXECUTE PROCEDURE describe();

postgres@subscriber=# CREATE TRIGGER t_after_row AFTER INSERT OR UPDATE OR DELETE ON t FOR EACH ROW EXECUTE PROCEDURE describe();

postgres@subscriber=# CREATE TRIGGER t_before_stmt BEFORE INSERT OR UPDATE OR DELETE ON t FOR EACH STATEMENT EXECUTE PROCEDURE describe();

postgres@subscriber=# CREATE TRIGGER t_after_stmt AFTER INSERT OR UPDATE OR DELETE ON t FOR EACH STATEMENT EXECUTE PROCEDURE describe();

postgres@subscriber=# CREATE SUBSCRIPTION testsub CONNECTION 'host=localhost port=5432 user=postgres dbname=postgres' PUBLICATION testpub;

#
# publisher
#

postgres@publisher=# INSERT INTO t VALUES (1);
INSERT 0 1

#
# subscriber
#

postgres@subscriber=# SELECT * FROM t;
 n
---
 1
(1 row)

postgres@subscriber=# SELECT * FROM log;
 tg_table_name | tg_when | tg_op | tg_level | tg_str
---------------+---------+-------+----------+--------
(0 rows)

#
# so replication works, but triggers don't.
# now check that triggers work alright locally:
#

postgres@subscriber=# INSERT INTO t VALUES (100);
INSERT 0 1

postgres@subscriber=# SELECT * FROM log;
 tg_table_name | tg_when | tg_op  | tg_level  | tg_str
---------------+---------+--------+-----------+--------
 t             | BEFORE  | INSERT | STATEMENT |
 t             | BEFORE  | INSERT | ROW       | (100)
 t             | AFTER   | INSERT | ROW       | (100)
 t             | AFTER   | INSERT | STATEMENT |
(4 rows)


Regards,
Egor Rogov
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company



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