Re: help with rule and notification
От | Theodore Petrosky |
---|---|
Тема | Re: help with rule and notification |
Дата | |
Msg-id | 20031002123409.10401.qmail@web41008.mail.yahoo.com обсуждение исходный текст |
Ответ на | Re: help with rule and notification (Tom Lane <tgl@sss.pgh.pa.us>) |
Список | 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@sss.pgh.pa.us> wrote: > Theodore Petrosky <tedpet5@yahoo.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
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