Re: 291 pg_toast_temp schemas?

summary: database has 291 empty pg_toast_temp schemas.
severity: head-scratcher
version: 9.0.7
platform: RHEL6

description:

* medium-large production database (300GB)
* does data collection and analytics
* lately has been having chronic lock-blocking issues
* does many, daily batch jobs which involve the creation of many temp
tables.

Today, while investigating the lock-blocking issues, I noticed that the
db has pg_toast_temp_1 through 291. All of these schema are completely
empty:

breakpad=# select schemaname, relname from pg_stat_all_tables where
schemaname LIKE 'pg_toast_temp_%';
schemaname | relname
------------+---------

... so, apparently we still have an issue with cleaning up pg_toast_temp
schema?

--
Josh Berkus
PostgreSQL Experts Inc.
http://pgexperts.com

Josh Berkus <josh(at)agliodbs(dot)com> writes:
> summary: database has 291 empty pg_toast_temp schemas.

If your max_connections is 300 or more, this isn't surprising in the
least.

> ... so, apparently we still have an issue with cleaning up pg_toast_temp
> schema?

If they are empty, no we don't have a problem with cleaning them up.
The pg_namespace entries are deliberately left there across sessions,
to avoid useless catalog churn.

regards, tom lane

On 4/26/12 11:22 AM, Tom Lane wrote:
> Josh Berkus <josh(at)agliodbs(dot)com> writes:
>> summary: database has 291 empty pg_toast_temp schemas.
>
> If your max_connections is 300 or more, this isn't surprising in the
> least.

Yes, they are.

>> ... so, apparently we still have an issue with cleaning up pg_toast_temp
>> schema?
>
> If they are empty, no we don't have a problem with cleaning them up.
> The pg_namespace entries are deliberately left there across sessions,
> to avoid useless catalog churn.

Aha, ok. Should I add a FAQ item about this?

Also, have we discussed maybe hiding these schemas from \dn?

--
Josh Berkus
PostgreSQL Experts Inc.
http://pgexperts.com

On Thu, Apr 26, 2012 at 5:35 PM, Josh Berkus <josh(at)agliodbs(dot)com> wrote:
>
> Also, have we discussed maybe hiding these schemas from \dn?
>

+1 from this idea... maybe do them visible only on \dn+

--
Jaime Casanova         www.2ndQuadrant.com
Professional PostgreSQL: Soporte 24x7 y capacitación

Josh Berkus <josh(at)agliodbs(dot)com> writes:
> Also, have we discussed maybe hiding these schemas from \dn?

We've done more than discuss it:
http://git.postgresql.org/gitweb/?p=postgresql.git&a=commitdiff&h=e43fb604d6db229d70d3101aa53348cc16a5473a

I take it you're using something older than 9.1.

regards, tom lane

On Thu, Apr 26, 2012 at 5:48 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Josh Berkus <josh(at)agliodbs(dot)com> writes:
>> Also, have we discussed maybe hiding these schemas from \dn?
>
> We've done more than discuss it:
> http://git.postgresql.org/gitweb/?p=postgresql.git&a=commitdiff&h=e43fb604d6db229d70d3101aa53348cc16a5473a
>
> I take it you're using something older than 9.1.
>

that's a quick reaction :D

--
Jaime Casanova         www.2ndQuadrant.com
Professional PostgreSQL: Soporte 24x7 y capacitación

On 4/26/12 3:48 PM, Tom Lane wrote:
> Josh Berkus <josh(at)agliodbs(dot)com> writes:
>> Also, have we discussed maybe hiding these schemas from \dn?
>
> We've done more than discuss it:
> http://git.postgresql.org/gitweb/?p=postgresql.git&a=commitdiff&h=e43fb604d6db229d70d3101aa53348cc16a5473a
>
> I take it you're using something older than 9.1.

Yep, 9.0.7 per bug.

Thanks!

--
Josh Berkus
PostgreSQL Experts Inc.
http://pgexperts.com