>>>>> "Greg" == "Greg Sabino Mullane" <g...@turnstep.com> writes:
>> They're mostly a foot-gun. Greg> Lots of things in Postgres could be considered potential foot Greg> guns. Frankly, I don't think rules are even near the top of Greg> such a list. Can you give examples of rule foot guns? There are so many it's hard to know where to start. Here are a couple of the more common ones: 1) any reference in an insert rule to NEW.col where col has a volatile default, or the expression in the insert statement was volatile, or the expression's value is changed by the insert, will do the wrong thing: create table t (a integer); create table t_log (a integer); create rule t_ins AS ON insert TO t do also insert into t_log values (NEW.a); insert into t values (floor(random()*1000)::integer); select * from t; a ---- 33 (1 row) select * from t_log; a ----- 392 (1 row) (think "nextval" or "uuid_generate_*" for more realistic examples) 2) any rule with multiple actions, each action is affected by the results of the previous ones. A classic example of this is in the use of OLD in delete or update rules; OLD _does not return a row_ if a previous action in the rule deleted the row or updated it so that it no longer matches. -- Andrew (irc:RhodiumToad) -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
