Re: BUG #5606: DEFERRABLE and DEFERRABLE INITIALLY DEFERRED are the same

The manual looks fine, I found the information as well. I started using the=
 wiki, that's why I got confused.

Thanks!

Frank

-----Oorspronkelijk bericht-----
Van: Tom Lane [mailto:tgl@sss.pgh.pa.us]
Verzonden: vrijdag 6 augustus 2010 17:04
Aan: Frank Heikens
CC: pgsql-bugs@postgresql.org
Onderwerp: Re: [BUGS] BUG #5606: DEFERRABLE and DEFERRABLE INITIALLY DEFERR=
ED are the same

Frank Heikens <f.heikens@anva.nl> writes:
> The wikipage says
>> a deferrable constraint CAN be checked at the end of a
>> transaction. You still have to ask PostgreSQL to defer it.
> http://wiki.postgresql.org/wiki/What%27s_new_in_PostgreSQL_9.0#DEFERRABLE=
_UNIQUE_CONSTRAINTS

> I don't have to ask PostgreSQL to defer, it works in the second test
as well in the third test without any changes. I guess the example in
the wiki isn't correct, right?

No, not even a little bit :-(.  I hadn't seen that text; it needs to be
corrected.  Will hack on it in a moment.

> A single UPDATE touching all records will check the uniqueness after the =
complete update, not right after each update of a row as it does on non-def=
errable constraints.

Right.
non-deferrable -> uniqueness is enforced after each row change
DEFERRABLE IMMEDIATE -> uniqueness is enforced at end of statement
DEFERRABLE DEFERRED -> uniqueness is enforced at end of transaction

> Maybe someone could make this clear in the manual and wiki?

AFAIK the manual is OK; do you see a place where it gets this wrong?

                        regards, tom lane

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