Обсуждение: strange behavior on locks

Hi, 

I running PostgreSQL 8.0.x with database that does not have foreign keys
and sometimes the following messages appears:

ERROR:  deadlock detected
DETAIL:  Process 10029 waits for ShareLock on transaction 65272; blocked
by process 32436.       Process 32436 waits for ShareLock on transaction 65117; blocked
by process 10029.

I also see (right after executing a ps) that there are lots of messages
"select waiting".

1 - Does it mean that process 10029 owns transaction  65117 and 
process 32436 owns transaction 65272 as a transaction acquires an
exclusive lock in its transaction id ?
2 - How is this situation possible ?
What could cause the status ("select waiting") ?

Best regards, 

Alfranio

Alfranio Correia Junior <alfranio@lsd.di.uminho.pt> writes:
> What could cause the status ("select waiting") ?

Perhaps you are using SELECT FOR UPDATE?
        regards, tom lane

On Fri, Jan 20, 2006 at 11:47:55PM -0500, Tom Lane wrote:
> Alfranio Correia Junior <alfranio@lsd.di.uminho.pt> writes:
> > What could cause the status ("select waiting") ?
> 
> Perhaps you are using SELECT FOR UPDATE?

or SELECT func_with_side_effects() ? 
-Mike

Perhaps you are using SELECT FOR UPDATE?

I am not using "SELECT FOR UPDATES"...
Could it have another cause ?

I am executing some stored procedures written in pl/pgsql....
But wouldn't PostgreSQL show information per statement executed by the 
functions ?

>or SELECT func_with_side_effects() ? 
>
> -Mike
>
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Alfranio Correia Junior <alfranio@lsd.di.uminho.pt> writes:
> I am executing some stored procedures written in pl/pgsql....
> But wouldn't PostgreSQL show information per statement executed by the 
> functions ?

No.  The command shown in the process status is always just the
outermost operation.
        regards, tom lane