php-psql lock problem. Thanks!

Hello to everybody!

I've a little problem with LOCK-ing a
certain row in a table using PHP and
PostgreSQL on LINUX.
>> In a few words, I'd like to undertand>> how find out if a certain row is locked,>> in order to prevent a kind of
deadlock.

Which is the (system) table where all
locked row or tables are 'saved' ?
Is there any flag?

// ############################
Example 1:

User A:

BEGIN WORK;
select login from people where userid='1' for update;
[ ... ]
COMMIT WORK;

User B:
BEGIN WORK;
(***)
select login from people where userid='1' for update;

[ WAIT UNTIL 'COMMIT WORK' of user A  !  :(  ]

COMMIT WORK;

Solution:
I'd like to put in (***) a quick check in order to
know if the row with userid='1' is already locked or not.

In this way, if it's already locked, I'll use   select login from people where userid='1';     [ ONLY READ ]
instead of   select login from people where userid='1' for update;     [READ & WRITE]

// ############################
Example 2:

BEGIN WORK;
LOCK TABLE utenti IN SHARE ROW EXCLUSIVE MODE;
select login from people where userid='1';
COMMIT WORK;

// ############################


Many thanks to everybody!
Ciao!
MaURIZIO

crix98@____tin.it


It's sure that a small example in PHP will very very appreciated!! :))


PS: it's possible to setup a timeout for a locked table,    in order to exec an aoutomatic ROLLBACK ??    (for examples
ifthe user goes away?
 

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