Re: [Fwd: Re: deadlock on the same relation]

"Francesco Formenti - TVBLOB S.r.l." <francesco(dot)formenti(at)tvblob(dot)com> writes:
> Tom Lane wrote:
>> Probably you have been careless about avoiding "lock upgrade"
>> situations.

> Unfortunately, the first operation I do after the "BEGIN" declaration is
> the LOCK TABLE in access exclusive mode, and is the only explicit lock I
> perform in all the stored procedures.

If you mean that you placed a LOCK TABLE inside the stored procedure,
that's far from being the same thing as the start of the transaction.
For example, if your application does

BEGIN;
SELECT * FROM mytab;
SELECT myprocedure();
COMMIT;

then by the time control arrives inside myprocedure your transaction
already holds a nonexclusive lock on "mytab". If you do LOCK TABLE mytab
inside the function then you're risking deadlock.

regards, tom lane