Re: [GENERAL] Postgres concurrency : urgent

On Fri, 12 Nov 1999, V Krishnaraj wrote:

> Hi,
>
> I'm having a postgres database accessed from perl using DBI and
> DBD.
>
> This application works fine when we are in single user. When we
> go into multi-user, the app has concurrency problems.
>
> The application has a sql query and updates onto the base table in
> the sql query. We are using Select FOR UPDATE to open the
> cursor and multiple update statements to update values on different
> base tables. When multiple users are running the program, after a
> few iterations postmaster startsputting out messages that there are
> concurrency problems due to which the execute before the fetch
> fails.
> What I want to do is to wait for the other transactions updates to
> get over and retry opening the cursor. This does not happen.
> The moment I try to open the cursor again (using execute),
> postmaster says that there is no connection !!
>
> If I try and reconnecting again it starts giving pqreaddata() problems.
> After sometime server crashes !!
>
> We are using postgres 6.5.1, DBI-1.13, DBD 0.92
>
> Please somebody help.
>
> Thanks and regards,
>
> Kimi

I 'm using :

LOCK <<tablename>> IN ACCESS EXCLUSIVE MODE;

to control concurrent transactions - it works for me
(postgres 6.5.2)

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Marcin Inkielman

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