Re: Turning off HOT/Cleanup sometimes

On Mon, Apr 20, 2015 at 09:56:20PM +0100, Simon Riggs wrote:
> On 20 April 2015 at 20:28, Jeff Janes <jeff.janes@gmail.com> wrote:
>  
> 
>     But why should 1 SELECT or 20 SELECTs or 200 SELECTs have to do a job,
>     while the user waits, which is fundamentally VACUUM's duty to do in the
>     background? 
> 
> 
> Agreed. I don't see a % as giving us anything at all.
> 
> The idea is that we want to turn an O(N) problem for one query into an O(1)
> task.
>  
> 
>     The use case I see for this is when there is a mixed workload.  There is
>     one select which reads the entire table, and hundreds of thousands of
>     selects/updates/insert that don't, and of course vacuum comes along every
>     now and then and does it thing.  Why should the one massive SELECT have
>     horrible performance just because it was run right before autovacuum would
>     have kicked in instead of right after if finished?
> 
> 
> +1

You can +1 all you want, but if you ignore the specific workloads I
mentioned, you are not going to get much traction.

--  Bruce Momjian  <bruce@momjian.us>        http://momjian.us EnterpriseDB
http://enterprisedb.com
 + Everyone has their own god. +