From: Merlin Moncure <mmoncure@gmail.com>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Mladen Gogala <mladen.gogala@vmsinfo.com>; pgsql-performance@postgresql.org
Sent: Wed, October 27, 2010 4:46:53 AM
Subject: Re: [PERFORM] Postgres insert performance and storage requirement compared to Oracle
On Tue, Oct 26, 2010 at 6:50 PM, Robert Haas <
robertmhaas@gmail.com> wrote:
> On Tue, Oct 26, 2010 at 5:54 PM, Mladen Gogala
> <
mladen.gogala@vmsinfo.com> wrote:
>> The table is created with "on commit obliterate rows" option which means
>> that there is no need to do "truncate". The "truncate" command is a heavy
>> artillery. Truncating a temporary table is like shooting ducks in a duck
>> pond, with a howitzer.
>
> This is just not true. ON COMMIT DELETE ROWS simply arranges for a
> TRUNCATE to happen immediately before each commit. See
> PreCommit_on_commit_actions() in tablecmds.c.
quite so. If you are doing anything performance sensitive with 'on
commit drop', you are better off organizing a cache around
txid_current() (now(), pid for older pg versions). Skips the writes
to the system catalogs and truncate.
merlin
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