Re: Queries intermittently slow

On 1/6/16, 10:38 AM, "Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:

>
>A possible theory is that the slow cases represent times when the desired
>page is not in cache, but you'd have to have a seriously overloaded disk
>subsystem for a disk fetch to take hundreds of ms. Unless maybe this is
>running on some cloud service with totally unspecified I/O bandwidth?

This intrigues me. We are running on a, shall we say, less than name-brand cloud provider at the moment (transitioning to AWS later this month). Is there a reasonably straightforward way of confirming this hypothesis? We have had many performance issues with this vendor in the past, so I wouldn’t be surprised.

>
>> I will look at changing the deadlock_timeout, but that might have to wait for the weekend since this is a production system.
>
>You needn't restart the server for that, just edit postgresql.conf and
>SIGHUP the postmaster.

Yep, we just try to limit any database changes until off-hours unless it’s an emergency.

>
>regards, tom lane

Thanks,
Scott
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.