Re: Checkpoint_segments optimal value - Mailing list pgsql-general

From Prabhjot Sheena
Subject Re: Checkpoint_segments optimal value
Date
Msg-id CAOf_bQaRBDorZnjhBqM451mmsorac=9LSGP0b5ZNkUP9heo+OQ@mail.gmail.com
Whole thread Raw
In response to Re: Checkpoint_segments optimal value  (Tom Lane <tgl@sss.pgh.pa.us>)
Responses Re: Checkpoint_segments optimal value  (Potentialtech <wmoran@potentialtech.com>)
Re: Checkpoint_segments optimal value  (John R Pierce <pierce@hogranch.com>)
List pgsql-general
Thanks i have changed that to 64 and reloaded it.

When i had load issue today there was this exact same query that hits the db like 50 to 60 times from different machines in 3 to 4 minutes and was taking long time to execute and was holding up the database. i did recreate an index and it started performing better. My question is why it is not fetching the result from the memory since  its the same query that runs again and again.

This is the actual query i m taking about:

SELECT account.id, account.organization_id, run.application_id, work_unit.script, work_unit.id, work_unit.start_time, run.id, work_unit.priority  FROM work_unit, run, account  WHERE  work_unit.status = 3 AND work_unit.run_id = run.id AND work_unit.type != 1 AND run.status = 1 AND run.account_id = account.id

Pls suggest if i can do something to fix this


On Thu, Jul 17, 2014 at 11:06 AM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
Potentialtech <wmoran@potentialtech.com> writes:
> If the warning isn't happening too often, I would try increasing it only a
> little and see if it helps.  If it's not enough you can then increase it some
> more.  Various sources around the Internet suggest that you don't want to go
> much larger than 256 for this (if only because it's uncommon to do so and is
> probably indicative of other tuning that you need to do).  Unfortunatley, you
> need to restart PG for the change to take effect, so you have to balance
> experimenting with your tuning against how often you can get away with a server
> restart.

Huh?  You don't need a restart, just a reload (SIGHUP) to change that.

                        regards, tom lane

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