On Aug9, 2011, at 22:40 , Tom Lane wrote: > Alvaro Herrera <alvhe...@commandprompt.com> writes: >> Excerpts from Jeff Davis's message of mar ago 09 14:41:14 -0400 2011: >>> Right now, FKs aren't really very special, they are mostly just >>> syntactic sugar (right?). This proposal would make FKs special internal >>> mechanisms, and I don't see the benefit in doing so. > >> Well, you can get the same behavior by adding the constraint triggers >> manually. But those triggers are written in C, so you could equally >> claim that they are "special internal" already. The SPI interface has >> some special entry points to allow them to work correctly (for example >> passing a snapshot for the checks to run with). > > Yeah, the crosscheck-snapshot logic already puts the lie to any idea > that the RI triggers are equivalent to anything available at the SQL > level.
True, but I still considered that to be a quite unfortunate limitation, and one that I hope to one day remove. So I'd hate to see us adding more stumbling blocks along that road. Even today, you can do user-space FK-like constraint if you restrict yourself to either running all transaction in isolation level READ COMMITTED, or all transactions in isolation level SERIALIZABLE (Though I in the later case, you don't need locks anyway..) best regards, Florian Pflug -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
