On 09/30/2014 09:10 PM, Gregory Smith wrote:
> On 9/29/14, 2:30 PM, Andres Freund wrote:
>>> Can we explain those reasons in the form of documentation?
>> Yes. Try and benchmark it. It'll be hardware and workload dependant.
>
> I missed this whole thing, and eventually I have to circle back to it.
> I could do it this week.
Ah, that would be great!
> Could you (or someone else familiar with the
> useful benchmarks) give me more detail on how to replicate one case
> where things should improve? I can do that, and I have a lab full of
> hardware if it's easier to spot on one type of server. That exercise
> will probably lead to a useful opinion on the feature in its final form,
> any associated GUC, tunables, and necessary level of associated
> documentation in a day or two.
To see the most improvement from the patch, try a workload that's
otherwise bottlenecked on XLogInsert. For example, with pgbench:
psql postgres -c "create table foo (id int4)"
pgbench postgres -n -f fooinsert.sql -c 4 -T10
and in the test script:
insert into foo select g from generate_series(1, 10000) g;
- Heikki
