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

From Kouber Saparev
Subject Re: DELETE takes too much memory
Date
Msg-id CAN4RuQt5GZEbkHdPmm=j-z2uE3m3U-USWFNhVRiqYAKv5BZqhg@mail.gmail.com
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In response to Re: DELETE takes too much memory  (Alvaro Herrera <alvherre@2ndquadrant.com>)
List pgsql-performance
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.

2016-07-04 20:04 GMT+03:00 Alvaro Herrera <alvherre@2ndquadrant.com>:
Kouber Saparev wrote:
> I tried to DELETE about 7 million rows at once, and the query went up to
> 15% of the RAM (120 GB in total), which pushed some indexes out and the
> server load went up to 250, so I had to kill the query.
>
> The involved table does not have neither foreign keys referring to other
> tables, nor other tables refer to it. The size of the table itself is 19 GB
> (15% of 120 GB). So why the DELETE tried to put the entire table in memory,
> or what did it do to take so much memory?

Are there triggers in the table?  Deferred triggers in particular can
use memory.

--
Álvaro Herrera                http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

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