Re: Possible causes of sometimes slow single-row UPDATE with trivial indexed condition?

Vlad Romascanu wrote:
> Problem occurs when running (in production) Postgres 8.3.7 64-bit (from
> RPM) on Ubuntu 8.04.2, on an Amazon EC2 (xen) "Large" instance (8GB
> RAM), with the DB on a 50GB EC2 block device.
> Problem does not occur when running (in staging/pre-production) Postgres
> 8.3.5 32-bit (from RPM) on Ubuntu 8.04.1, on a less beefy Amazon EC2
> (xen) "Small" instance, with the DB on a 5GB EC2 block device.
>
> I am running with slow query logging on, and somewhat inexplicably I've
> been getting the following slow UPDATE query several times in the past
> weeks (I'm also including some context lines above and below):
>

I'm not sure how Amazon vm's work, but are there multiple vm's on one
box?  Just because your vm has zero cpu/disk does not mean the host
isn't pegged out of its mind.

Does Amazon give any sort of host stats?

-Andy