Re: proposal: Set effective_cache_size to greater of .conf value, shared_buffers

On 05/07/2014 01:36 PM, Jeff Janes wrote:
> On Wed, May 7, 2014 at 11:04 AM, Josh Berkus <josh@agliodbs.com> wrote:

>> Unfortunately nobody has the time/resources to do the kind of testing
>> required for a new recommendation for shared_buffers.

> I think it is worse than that.  I don't think we know what such testing
> would even look like.  SSD?  BBU? max_connections=20000 with 256 cores?
>  pgbench -N?  capture and replay of Amazon's workload?
> 
> If we could spell out/agree upon what kind of testing we would find
> convincing, that would probably go a long way to getting some people to
> work on carrying out the tests.  Unless the conclusion was "please have 3TB
> or RAM and a 50 disk RAID", then there might be few takers.

Well, step #1 would be writing some easy-to-run benchmarks which carry
out selected workloads and measure response times.  The minimum starting
set would include one OLTP/Web benchmark, and one DW benchmark.

I'm not talking about the software to run the workload; we have that, in
several varieties.  I'm talking about the actual database generator and
queries to run.  That's the hard work.

-- 
Josh Berkus
PostgreSQL Experts Inc.
http://pgexperts.com