Re: Cannot DROP while process running

Here is the result of this select:
select datname, procpid, current_query from pg_stat_activity;

As you can see, there appears to be no connection to the other tables with
the AccessShareLocks.

mapping=# select datname, procpid, current_query from pg_stat_activity;
datname | procpid | current_query
----------+---------+----------------------------------------------------------------------------------
postgres | 23424 | <IDLE>
mapping | 22787 | select datname, procpid, current_query from
pg_stat_activity;
mapping | 16193 | SELECT * FROM public.assign_vertex_id('raw_tomtom',
0.00001, 'the_geom', 'gid');
mapping | 23425 | <IDLE>
mapping | 20897 | autovacuum: VACUUM ANALYZE public.raw_tomtom
mapping | 20405 | LOCK TABLE public.vertices_tmp IN ACCESS SHARE MODE
mapping | 19461 | LOCK TABLE public.vertices_tmp IN ACCESS SHARE MODE
mapping | 23426 | <IDLE>
mapping | 20466 | LOCK TABLE public.vertices_tmp IN ACCESS SHARE MODE
mapping | 8059 | <IDLE>
mapping | 20976 | <IDLE>

Thanks for your help on this.

2012/4/9 Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>

> Steve Horn <steve(at)stevehorn(dot)cc> writes:
> > I ran this command:
> > select pg_class.relname,pg_locks.* from pg_class,pg_locks where
> > pg_class.relfilenode=pg_locks.relation;
>
> > and it appears that almost every table in my database has
> > ""AccessShareLock". I have read that those locks are placed on tables for
> > SELECT access.
>
> Well, an AccessShareLock would definitely prevent you from dropping the
> table. The question is which session(s) are holding such locks and why.
> I suspect that you have some long-running transactions, perhaps
> accidentally so. As Devrim mentioned, joining pg_locks against
> pg_stat_activity would go a long way towards explaining what's blocking
> your DROP attempt.
>
> regards, tom lane
>

--
Steve Horn