Hi All,
I decided to go with the following fix. Instead of strait delete and insert
statements I am gonna use stored procedures for delete and insert:
CREATE OR REPLACE FUNCTION delete_group(integer)
RETURNS void AS
$BODY$
BEGIN
delete from infotest where infotest.groupid = $1;
RETURN;
END;
$BODY$
LANGUAGE 'plpgsql' VOLATILE;
CREATE OR REPLACE FUNCTION insert_group(integer, integer, timestamp with time
zone)
RETURNS void AS
$BODY$
BEGIN
insert into infotest (groupid, subgroupid, datemodified)
select $1,$2,$3 where 1 not in (select 1 from infotest where
groupid = $1 and subgroupid = $2);
RETURN;
END;
$BODY$
LANGUAGE 'plpgsql' VOLATILE
This solved my problem.
Sequoia is not gonna drop a backend if the delete returns different number of
updated rows (because the procedure returns void) and the record is not gonna
be inserted anymore if already exists in the table...
The info in this table is not critical and does not affect the functionality of
the application. Also is gonna be refreshed at each login. So I am sure I am
safe with this solution...
Thanks for the help,
Ioana
--- On Mon, 6/8/09, Ioana Danes <[email protected]> wrote:
> From: Ioana Danes <[email protected]>
> Subject: Re: [GENERAL] Duplicate key issue in a transaction block
> To: "Scott Marlowe" <[email protected]>
> Cc: "Bill Moran" <[email protected]>, "Vyacheslav Kalinin"
> <[email protected]>, "PostgreSQL General" <[email protected]>
> Received: Monday, June 8, 2009, 2:58 PM
>
> I am actually using Sequoia and the big problem is not the
> primary key error. I could leave with that!
> Sometimes the problem is generated not by insert but by the
> delete because the two transactions don't happen on the
> exactly same order and time on both backends and then the
> delete returns different updated records on the the db
> servers and sequoia drops one backend...
> That is my big pain...............
>
> I have some ideas I will test now and I will let you know
> which one I choose to fix my problem...
>
> Thanks a lot for your help,
> Ioana
>
>
> --- On Mon, 6/8/09, Scott Marlowe <[email protected]>
> wrote:
>
> > From: Scott Marlowe <[email protected]>
> > Subject: Re: [GENERAL] Duplicate key issue in a
> transaction block
> > To: "Ioana Danes" <[email protected]>
> > Cc: "Bill Moran" <[email protected]>,
> "Vyacheslav Kalinin" <[email protected]>,
> "PostgreSQL General" <[email protected]>
> > Received: Monday, June 8, 2009, 2:37 PM
> > On Mon, Jun 8, 2009 at 12:25 PM,
> > Ioana Danes<[email protected]>
> > wrote:
> > >
> > > Well, I guess I have my answer...
> > >
> > > I tried to narrow down an issue I get on one of
> the
> > production sites, where using a similar transaction I
> get
> > the same error.
> > >
> > > In my production environment the group id is
> actually
> > a unique number for the terminal (terminalid) and the
> same
> > transaction CANNOT be called for the same terminalid.
> So
> > this should never happen because each terminal has its
> own
> > ID and this procedure is called on login operation for
> each
> > terminal... At least that's what I thought so...
> > >
> > > But it does happen during the nightly online
> backup
> > (pg_dump).
> > > It looks like when the client logs in, the
> request is
> > sent from the client to the db, the backup (pg_dump)
> slows
> > down the server (or holds the lock on that table?) and
> the
> > user does not have patience and restarts the client
> and logs
> > in again.
> > > In this case I can get two parallel transactions
> for
> > the same terminal...
> >
> > You mentioned earlier you're using slony for
> replication,
> > so the
> > answer is obvious, run the backup against a read
> slave, and
> > set the
> > users, during backup, to only have access to the
> written to
> > master.
> >
>
>
>
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