Re: Queries intermittently slow

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On 1/6/16, 10:38 AM, "Tom Lane" <tgl@xxxxxxxxxxxxx> 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
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