Re: Huge shared hit for small table

From: Scott Rankin <srankin(at)motus(dot)com>
To: Peter Geoghegan <pg(at)bowt(dot)ie>
Cc: Jeff Janes <jeff(dot)janes(at)gmail(dot)com>, "pgsql-performance(at)lists(dot)postgresql(dot)org" <pgsql-performance(at)lists(dot)postgresql(dot)org>
Subject: Re: Huge shared hit for small table
Date: 2019-11-04 21:00:15
Message-ID: D6F15B3F-A4CB-4BDD-AC08-3FABC81D4404@motus.com
Views: Raw Message | Whole Thread | Download mbox | Resend email
Thread:
Lists: pgsql-performance

I think we have a winner. I looked in and found a process that was 'idle in transaction' for a couple days - and once I killed it, query performance went back to normal.

Thank you all for the very quick responses on this.

On 11/4/19, 3:41 PM, "Peter Geoghegan" <pg(at)bowt(dot)ie> wrote:

On Mon, Nov 4, 2019 at 12:38 PM Scott Rankin <srankin(at)motus(dot)com> wrote:
> Definitely no long-running transactions on this table; in fact, this table is pretty infrequently updated – on the order of a few tens of rows updated per day.

But a long running transaction will have an impact on all tables --
not just the tables that happen to have been accessed so far in the
long running transaction. This is necessary because nothing stops the
long running transaction from SELECTing data from any table at any
time -- we need to pessimistically keep around the data required to
make that work.

--
Peter Geoghegan

This email message contains information that Motus, LLC considers confidential and/or proprietary, or may later designate as confidential and proprietary. It is intended only for use of the individual or entity named above and should not be forwarded to any other persons or entities without the express consent of Motus, LLC, nor should it be used for any purpose other than in the course of any potential or actual business relationship with Motus, LLC. If the reader of this message is not the intended recipient, or the employee or agent responsible to deliver it to the intended recipient, you are hereby notified that any dissemination, distribution, or copying of this communication is strictly prohibited. If you have received this communication in error, please notify sender immediately and destroy the original message.

Internal Revenue Service regulations require that certain types of written advice include a disclaimer. To the extent the preceding message contains advice relating to a Federal tax issue, unless expressly stated otherwise the advice is not intended or written to be used, and it cannot be used by the recipient or any other taxpayer, for the purpose of avoiding Federal tax penalties, and was not written to support the promotion or marketing of any transaction or matter discussed herein.

In response to

Browse pgsql-performance by date

  From Date Subject
Next Message Jeff Janes 2019-11-04 21:05:12 Re: Huge shared hit for small table
Previous Message Peter Geoghegan 2019-11-04 20:40:46 Re: Huge shared hit for small table