Bug #722: SELECT FOR UPDATE bug

Pablo Aviles
27/07/2002 10:58


        To:     Tom Lane <tgl@sss.pgh.pa.us>
        cc:=20
        Subject:        Re: [BUGS] Bug #722: SELECT FOR UPDATE bug

=20
 Hi,
we are use Postgresql 7.3.
The case in questions is: we have many clients (pc's) of postgresql. Every=
=20
client try to block an employee to display at user. The user make change=20
in the employee, but nobody can take the same employee at same time.=20
Before changes, the next step is update the record (Record blocked)

But, when I use=20
>   SELECT * FROM employees=20
>   WHERE status =3D 'A'=20
>   LIMIT 1=20
>   FOR UPDATE;=20
to catch the employee, only the first user select a record. Other users=20
can`t select any employee until the first user release the record. The=20
first conclusion here, is that Postgresql block all employee table.
When we try to use the LOCK sentence, the result don=B4t have change.

regards,=20
Pablo Avil=E9s Cisneros
Technology, ITS=20
Software Development Area
Technology, ITS=20
San Jos=E9, Costa Rica
email: paviles@its.co.cr
=20
=20




Tom Lane <tgl@sss.pgh.pa.us>
27/07/2002 09:58

=20
        To:     paviles@its.co.cr, pgsql-bugs@postgresql.org
        cc:=20
        Subject:        Re: [BUGS] Bug #722: SELECT FOR UPDATE bug


pgsql-bugs@postgresql.org writes:
>   SELECT * FROM employees=20
>   WHERE status =3D 'A'=20
>   LIMIT 1=20
>   FOR UPDATE;=20

> The problem, in the previous sentence, is block every record on
> employees, although we want one record, we want limit 1.

I do not believe that.  Could you give a more complete example of
your problem?

It would also help if you'd state which Postgres version you're using.

                                                 regards, tom lane