Re: Blocking excessively in FOR UPDATE

On Fri, Nov 4, 2011 at 1:26 PM, Kevin Grittner
<Kevin(dot)Grittner(at)wicourts(dot)gov> wrote:
> As already pointed out, SELECT FOR UPDATE will require a disk write
> of the tuple(s) read.  If these are glutting, increasing
> shared_buffers would tend to make things worse.

I thought shared_buffers improved write caching.
We do tend to write onto the same rows over and over.

> Hopefully you have a BBU RAID controller configured for write-back.
> If not you should.  If you do, another thing which might help is
> increasing the cache on that controller.

Write-back on the RAID is another issue.
The controller is old and has a very small cache, we're already in the
process of securing a replacement.

> Or you could move WAL to a
> separate file system on a separate controller with its own BBU
> write-back cache.

WAL is already on a separate controller and array.