Thread: Notify rule

Hi!
I trying to create rule for update notifing:

CREATE OR REPLACE RULE "ttt_NotifyU" AS
    ON UPDATE TO "ttt" DO
 NOTIFY "ttt", '88';
this work.

But this
CREATE OR REPLACE RULE "ttt_NotifyU" AS
    ON UPDATE TO "ttt" DO
 NOTIFY "ttt", NEW."id";
don't (syntax error),
NOTIFY "ttt", CAST(NEW."id" as text)
too.

Q: How can I send tuple id (integer primary key) via notify using Rule?
    Target is erasing deprecated tuples from application's cache.

ivan_14_32 <ivan_14_32@mail.ru> writes:
> Q: How can I send tuple id (integer primary key) via notify using Rule?

You can't --- NOTIFY doesn't take variables in its parameters.
(That's a general property of utility commands, not just NOTIFY.)

Use the pg_notify() function, instead.

            regards, tom lane

On Tue, Feb 22, 2011 at 1:03 AM, ivan_14_32 <ivan_14_32@mail.ru> wrote:
> Hi!
> I trying to create rule for update notifing:
>
> CREATE OR REPLACE RULE "ttt_NotifyU" AS
>     ON UPDATE TO "ttt" DO
>  NOTIFY "ttt", '88';
> this work.
>
> But this
> CREATE OR REPLACE RULE "ttt_NotifyU" AS
>     ON UPDATE TO "ttt" DO
>  NOTIFY "ttt", NEW."id";
> don't (syntax error),
> NOTIFY "ttt", CAST(NEW."id" as text)
> too.
>
> Q: How can I send tuple id (integer primary key) via notify using Rule?
>     Target is erasing deprecated tuples from application's cache.

why use a rule here and not a trigger? triggers might be a bit more
verbose to right but explicit rules have and endless list of gotchas
and should be avoided unless you have a really good reason not to.

merlin

On Tue, Feb 22, 2011 at 1:03 AM, ivan_14_32 <ivan_14_32@mail.ru> wrote:
> Hi!
> I trying to create rule for update notifing:
>
> CREATE OR REPLACE RULE "ttt_NotifyU" AS
>     ON UPDATE TO "ttt" DO
>  NOTIFY "ttt", '88';
> this work.
>
> But this
> CREATE OR REPLACE RULE "ttt_NotifyU" AS
>     ON UPDATE TO "ttt" DO
>  NOTIFY "ttt", NEW."id";
> don't (syntax error),
> NOTIFY "ttt", CAST(NEW."id" as text)
> too.
>
> Q: How can I send tuple id (integer primary key) via notify using Rule?
>     Target is erasing deprecated tuples from application's cache.

Well, that second argument to NOTIFY must be a literal. If you need to notify with a dynamic value, then you need to
usethe pg_notify function instead--regardless of whether you use a rule or a trigger. 

--
Scott Ribe
scott_ribe@elevated-dev.com
http://www.elevated-dev.com/
(303) 722-0567 voice