Re: help with rule and notification

From: Theodore Petrosky <tedpet5(at)yahoo(dot)com>
To: pgsql-sql(at)postgresql(dot)org
Subject: Re: help with rule and notification
Date: 2003-10-02 12:34:08
Message-ID: 20031002123409.10401.qmail@web41008.mail.yahoo.com
Views: Raw Message | Whole Thread | Download mbox | Resend email
Thread:
Lists: pgsql-sql

ok if the only info I can pass is that the notify
happened and then I need to go look at the notifying
table is it possible to create a rule that on update
of jobstable insert into notifytable the jobnumber

has there been any real discussion about adding this
to the todo list?

I was really pretty excited about using notify,...

Ted

--- Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Theodore Petrosky <tedpet5(at)yahoo(dot)com> writes:
> > create rule r1 as on update to table1 do (update
> > table2 set jobno = table1.jobno; notify table2;)
>
> > so anyone listening for notifications on table2
> can
> > ask table2 for the jobno that was updated. then if
> > they were viewing that jobno, update their
> display. if
> > not just ignore the notify.
>
> At the moment, a NOTIFY cannot convey very much
> information beyond
> "something happened, better look to see what".
> (There have been
> discussions about making the notification carry more
> info, see the
> pgsql-hackers archives.) In a previous lifetime I
> had a moderately
> complex application that used NOTIFY to trigger
> display updates for
> multiple client apps viewing a shared database. If
> memory serves,
> I did it by having a "sequence number" column that
> was assigned from
> a nextval() operation on every insert or update. In
> addition the
> inserts and updates triggered NOTIFY events. When
> the clients
> got NOTIFY they'd do "select from tab where seqno >
> last-seqno-seen"
> and then update their local state from the rows they
> got back.
>
> This solution doesn't directly handle deletes. I
> think I finessed the
> problem by treating "delete" as "update to a 'dead'
> state" and only
> cleaning out the dead rows later.
>
> regards, tom lane
>
> ---------------------------(end of
> broadcast)---------------------------
> TIP 7: don't forget to increase your free space map settings

__________________________________
Do you Yahoo!?
The New Yahoo! Shopping - with improved product search
http://shopping.yahoo.com

In response to

Browse pgsql-sql by date

  From Date Subject
Next Message Tom Lane 2003-10-02 14:35:15 Re: output
Previous Message Richard Huxton 2003-10-02 12:17:24 Re: output