On 16 Aug 2010, at 10:45, <atul.g...@globaldatapoint.com> <atul.g...@globaldatapoint.com> wrote:
> Hi Alban, > > Thanks for the reply. > > I checked that Notify will not work till the transaction is commited. So in > our case since the transaction is being rolled back there will be no notify. Ah, you're right! I totally forgot about that... > Is there any other way of inter process communication in Postgres. Of course there is :) There's nothing stopping you from writing a few custom functions in an untrusted language that does your IPC for you. C comes to mind, but PL/Perlu, PL/PythonU, etc. should be able to do it as well (and probably easier). Usually if you're talking about performing I/O external to the database you'll get warned that transactions involving those calls can't be rolled back, but in this case that's exactly what you want. Now I know that Postgres uses some IPC internally as well (at least shared memory), so maybe it's possible to use some of the internal mechanisms. I have no idea whether that's possible or at all advisable, I'm sure someone (probably Tom) will chime in regarding that. Cheers! > -----Original Message----- > From: Alban Hertroys [mailto:dal...@solfertje.student.utwente.nl] > Sent: 13 August 2010 17:50 > To: Atul Goel > Cc: pgsql-general@postgresql.org > Subject: Re: [GENERAL] good exception handling archiecutre > > On 13 Aug 2010, at 14:07, <atul.g...@globaldatapoint.com> > <atul.g...@globaldatapoint.com> wrote: > >> How can we do error logging in Postgres. I am trying to create a >> LOG_AND_STOP method which would be generic to the code. I have pasted the >> code I have written. This code returns no data which is understandable as >> the error is thrown to the external world. >> >> Can I write the code somehow. >> >> CREATE SCHEMA test >> AUTHORIZATION postgres; >> >> CREATE TABLE test.error_log >> ( >> error_desc text >> ); >> >> >> CREATE OR REPLACE FUNCTION test.log_and_stop(err_desc text) >> RETURNS void AS >> $BODY$ >> Declare >> x integer; >> begin >> begin >> insert into test.error_log values (err_desc); >> end; >> begin >> raise exception '%',err_desc; > > Your transaction got rolled back here, hence the lack of data in your > error_log table. > > I don't think there's any way to log errors into a table from within the same > transaction, you'll probably need to use a separate connection for the > logging. I think LISTEN/NOTIFY may come in handy there. > >> end; >> end; >> $BODY$ >> LANGUAGE 'plpgsql' VOLATILE >> COST 100; >> ALTER FUNCTION test.log_and_stop(text) OWNER TO postgres; > > Alban Hertroys > > -- > If you can't see the forest for the trees, > cut the trees and you'll see there is no forest. > > > > > > This e-mail is confidential and should not be used by anyone who is not the > original intended recipient. Global DataPoint Limited does not accept > liability for any statements made which are clearly the sender's own and not > expressly made on behalf of Global DataPoint Limited. No contracts may be > concluded on behalf of Global DataPoint Limited by means of e-mail > communication. Global DataPoint Limited Registered in England and Wales with > registered number 3739752 Registered Office Middlesex House, 34-42 Cleveland > Street, London W1T 4LB > > -- > Sent via pgsql-general mailing list (pgsql-general@postgresql.org) > To make changes to your subscription: > http://www.postgresql.org/mailpref/pgsql-general > Alban Hertroys -- If you can't see the forest for the trees, cut the trees and you'll see there is no forest. !DSPAM:737,4c697052967632122118857! -- Sent via pgsql-general mailing list (pgsql-general@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
