Re: DELETE takes too much memory - Mailing list pgsql-performance

From Kouber Saparev
Subject Re: DELETE takes too much memory
Date
Msg-id CAN4RuQtDxv0tAs=bY-6RyhSfUxPRc=XJV-6iLrP+yyE9snJDQQ@mail.gmail.com
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In response to Re: DELETE takes too much memory  (Josh Berkus <josh@agliodbs.com>)
Responses Re: DELETE takes too much memory  (Jim Nasby <Jim.Nasby@BlueTreble.com>)
List pgsql-performance
Well, basically there are only INSERTs going on there (it is a table holding audit records for each DML statement). I do not see how a DELETE statement could block an INSERT?

You are correct that rebuilding the table will be faster, but then, there is a chance that some INSERT's will be blocked and eventually will fail (depending on the duration of the rebuilding, the exact moment I run it, and the involved operations on the other tables).

Could such a memory consumption be related to a GET DIAGNOSTICS plpgsql block? The delete itself is within a stored procedure, and then I return the amount of the deleted rows from the function:

DELETE FROM
  audits.audits
WHERE
  id <= last_synced_audits_id;

GET DIAGNOSTICS counter = ROW_COUNT;

RETURN counter;


2016-07-05 21:51 GMT+03:00 Josh Berkus <josh@agliodbs.com>:
On 07/04/2016 10:10 AM, Kouber Saparev wrote:
> No. There are AFTER triggers on other tables that write to this one
> though. It is an audits table, so I omitted all the foreign keys on purpose.

Is it possible that the DELETE blocked many of those triggers due to
locking the same rows?

Incidentally, any time I get into deleting large numbers of rows, I
generally find it faster to rebuild the table instead ...

--
--
Josh Berkus
Red Hat OSAS
(any opinions are my own)

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