Horton

Re: Temporary tables prevent autovacuum, leading to XID wraparound

Michael Paquier <michael@paquier.xyz>

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From: Michael Paquier <michael@paquier.xyz>
To: Andres Freund <andres@anarazel.de>
Cc: pgsql-hackers@lists.postgresql.org, "Tsunakawa, Takayuki" <tsunakawa.takay@jp.fujitsu.com>, Kyotaro HORIGUCHI <horiguchi.kyotaro@lab.ntt.co.jp>, "tgl@sss.pgh.pa.us" <tgl@sss.pgh.pa.us>, "robertmhaas@gmail.com" <robertmhaas@gmail.com>, "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>
Date: 2018-08-09T07:00:29Z
Lists: pgsql-hackers

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On Thu, Aug 09, 2018 at 08:32:32AM +0530, Andres Freund wrote:
> My point is that the documentation isn't sufficient. Not that there's an active problem.

OK.  Attached is the latest version if the patch I have that I was
preparing for commit.

On top of isTempNamespaceInUse I have this note:
+ * Note: this can be used while scanning relations in pg_class to detect
+ * orphaned temporary tables or namespaces with a backend connected to a
+ * given database.

Would you be fine if I add an extra note like what's in
BackendIdGetProc?  Say "The result may be out of date quickly, so the
caller must be careful how to handle this information."
--
Michael

Commits

  1. Clarify comment about assignment and reset of temp namespace ID in MyProc

  2. Make autovacuum more aggressive to remove orphaned temp tables

  3. Don't count background workers against a user's connection limit.