Обсуждение: Attempting to disable count triggers on cleanup

I have a database that we want to keep track of counts of rows.

We have triggers on the rows which increment, and decrement a count
table. In order to speed up deleting many rows we have added the following

   if user != 'mocospace_cleanup'
then

        update user_profile_count set buddycount=buddycount-1 where
user_profile_count.uid=OLD.userid;
    end
if;


However in the logs we can see the following. I have checked to make
sure that the user really is the mocospace_cleanup user and checked
manually by logging in as the mocospace_cleanup user to make sure that
the code above does what it purports to.

ERROR:  deadlock detected
DETAIL:  Process 23063 waits for ExclusiveLock on tuple (20502,48) of
relation 48999028 of database 14510214; blocked by process 23110.
Process 23110 waits for ShareLock on transaction 1427023217; blocked by
process 23098.
...
CONTEXT:  SQL statement "update user_profile_count set
buddycount=buddycount-1 where user_profile_count.uid= $1 "
PL/pgSQL function "user_buddy_count" line 11 at SQL statement
SQL statement "DELETE FROM ONLY "public"."user_buddies" WHERE
"buddyuserid" = $1"

Dave

On Tue, Sep 25, 2007 at 07:08:42AM -0400, Dave Cramer wrote:
> ERROR:  deadlock detected
> DETAIL:  Process 23063 waits for ExclusiveLock on tuple (20502,48) of
> relation 48999028 of database 14510214; blocked by process 23110.
> Process 23110 waits for ShareLock on transaction 1427023217; blocked by
> process 23098.
> ...
> CONTEXT:  SQL statement "update user_profile_count set
> buddycount=buddycount-1 where user_profile_count.uid= $1 "
> PL/pgSQL function "user_buddy_count" line 11 at SQL statement
> SQL statement "DELETE FROM ONLY "public"."user_buddies" WHERE
> "buddyuserid" = $1"

take a look at:
http://www.depesz.com/index.php/2007/09/12/objects-in-categories-counters-with-triggers/

and if you want to temporarily disable trigger, simply do appropriate
"alter table disable trigger".

depesz

--
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highly paid DBA.  here's my CV!" :)
http://www.depesz.com/ - blog dla ciebie (i moje CV)

hubert depesz lubaczewski wrote:
> On Tue, Sep 25, 2007 at 07:08:42AM -0400, Dave Cramer wrote:
>
>> ERROR:  deadlock detected
>> DETAIL:  Process 23063 waits for ExclusiveLock on tuple (20502,48) of
>> relation 48999028 of database 14510214; blocked by process 23110.
>> Process 23110 waits for ShareLock on transaction 1427023217; blocked by
>> process 23098.
>> ...
>> CONTEXT:  SQL statement "update user_profile_count set
>> buddycount=buddycount-1 where user_profile_count.uid= $1 "
>> PL/pgSQL function "user_buddy_count" line 11 at SQL statement
>> SQL statement "DELETE FROM ONLY "public"."user_buddies" WHERE
>> "buddyuserid" = $1"
>>
>
> take a look at:
> http://www.depesz.com/index.php/2007/09/12/objects-in-categories-counters-with-triggers/
>
> and if you want to temporarily disable trigger, simply do appropriate
> "alter table disable trigger".
>
>
Well, that doesn't work inside a transaction I've tried it. This has
been fixed in 8.3

Dave
> depesz
>
>