Re: [WIP] cache estimates, cache access cost

On Tue, Jun 14, 2011 at 1:10 PM, Greg Smith <greg(at)2ndquadrant(dot)com> wrote:
> On 06/14/2011 11:04 AM, Robert Haas wrote:
>> Even if the data were accurate and did not cause plan stability, we
>> have no evidence that using it will improve real-world performance.
>
> That's the dependency Cédric has provided us a way to finally make progress
> on.  Everyone says there's no evidence that this whole approach will improve
> performance.  But we can't collect such data, to prove or disprove it helps,
> without a proof of concept patch that implements *something*.  You may not
> like the particular way the data is collected here, but it's a working
> implementation that may be useful for some people.  I'll take "data
> collected at ANALYZE time" as a completely reasonable way to populate the
> new structures with realistic enough test data to use initially.

But there's no reason that code (which may or may not eventually prove
useful) has to be incorporated into the main tree. We don't commit
code so people can go benchmark it; we ask for the benchmarking to be
done first, and then if the results are favorable, we commit the code.

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company