Thread: undefined relations in pg_locks

Hi there,

Sorry I repeat a problem which concerned me since two months, but I got no 
answer. It's not clear for me whether it is trivial or without a solution. I 
promisse not to repeat it in the future if I will give no answer this time 
too.

So, I'm working with "PostgreSQL 8.2.3 on i686-redhat-linux-gnu, compiled by 
GCC gcc (GCC) 4.0.2 20051125 (Red Hat 4.0.2-8)";

I have a procedure where a dead-lock occurs, and I'm trying to find the 
tables involved in the lock.

A little description of how my procedure works maybe helps. So I have a loop 
where I call a second procedure with exception trapping. At its turn, it 
calls a third procedure. I guess an exception may occur in the third 
procedure, where I use a temporary table. When an exception occurs, I guess 
my temporary table table is not dropped, and this may lock the process when 
another call try to create that temporary table again. Could be this 
scenario what there happens to me ?

Unfortunatelly, I don't find the related objects of the oids of "relation" 
field. Also all the fields "classid" and "objid" are null.
May I suppose there were references to temporary tables?
However, how cand I get the related objects involved in this lock, by other 
way than analyse deeply in the code ?

TIA,
Sabin

"Sabin Coanda" <sabin.coanda@deuromedia.ro> writes:
> Unfortunatelly, I don't find the related objects of the oids of "relation" 
> field. Also all the fields "classid" and "objid" are null.
> May I suppose there were references to temporary tables?

Are you sure they are in the same database you are working in?  If the
locktype is "relation" and the database column matches your database's
OID, the relation column definitely ought to match some OID in pg_class.

It is possible that you can't see the pg_class row because the relation
was created in a transaction that hasn't committed yet --- but such an
entry could never be a reason for a deadlock, because no other
transaction could be trying to lock it.
        regards, tom lane

Oops! You are right. It was not a dead-lock.
I let the process to continue and after about one hour I got in the log the 
following message 'cannot have more than 2^32-1 commands in a transaction'.
After some investigations in the code I found an infinite loop.

Thanks and sorry for wasting time,
Sabin