Horton

Re: Assert failure due to "drop schema pg_temp_3 cascade" for temporary tables and \d+ is not showing any info after drooping temp table schema

Mahendra Singh Thalor <mahi6run@gmail.com>

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From: Mahendra Singh <mahi6run@gmail.com>
To: Michael Paquier <michael@paquier.xyz>
Cc: Kyotaro Horiguchi <horikyota.ntt@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2019-12-26T14:50:14Z
Lists: pgsql-bugs, pgsql-hackers 
On Thu, 26 Dec 2019 at 19:23, Michael Paquier <michael@paquier.xyz> wrote:
>
> On Wed, Dec 25, 2019 at 12:24:10PM +0900, Michael Paquier wrote:
> > Arf.  Yes, this had better be isAnyTempNamespace() so as we complain
> > about all of them.
>
> Okay, finally coming back to that.  Attached is an updated patch with
> polished comments and the fixed logic.

Thanks Michael for patch.

Patch is fixing all the issues.

I think, we can add a regression test for this.
postgres=# create temporary table temp(c1 int);
CREATE TABLE
postgres=# drop schema pg_temp_3 cascade ;
ERROR:  cannot drop temporary namespace "pg_temp_3"
postgres=#

I have one doubt. Please give me your opinion on below doubt.
Let suppose, I connected 10 sessions at a time and created 1 temporary
table to each session. Then it is creating schema from pg_temp_3 to
pg_temp_12 (one schema for each temp table session).  After that, I
closed all the 10 sessions but if I connect again any session and
checking all the schema, It is still showing pg_temp_3 to pg_temp_12.
Is this expected behavior ? or we should not display any temp table
schema after closing session. I thought that auto_vacuum wlll drop all
the temp table schema but it is not drooping.

Thanks and Regards
Mahendra Singh Thalor
EnterpriseDB: http://www.enterprisedb.com

Commits

  1. Avoid failure if autovacuum tries to access a just-dropped temp namespace.

  2. Revert "Forbid DROP SCHEMA on temporary namespaces"

  3. Forbid DROP SCHEMA on temporary namespaces

  4. Make autovacuum more aggressive to remove orphaned temp tables

  5. Code review for early drop of orphaned temp relations in autovacuum.