On Tue, 15 Jan 2019 at 13:17, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>
> David Rowley <david.rowley@2ndquadrant.com> writes:
> > I also did a quick benchmark of v6 and found the slowdown to be
> > smaller after the change made in build_simple_rel()
>
> Thanks for confirming. I was not very sure that was worth the extra
> few bytes of code space, but if you see a difference too, then it's
> probably worthwhile.
It occurred to me that a common case where you'll hit the new code is
INSERT INTO ... VALUES.
I thought I'd better test this, so I carefully designed the following
table so it would have as little INSERT overhead as possible.
create table t();
With fsync=off and a truncate between each pgbench run.
insert.sql = insert into t default values;
Unpatched:
$ pgbench -n -f insert.sql -T 60 postgres
tps = 27986.757396 (excluding connections establishing)
tps = 28220.905728 (excluding connections establishing)
tps = 28234.331176 (excluding connections establishing)
tps = 28254.392421 (excluding connections establishing)
tps = 28691.946948 (excluding connections establishing)
Patched:
tps = 28426.183388 (excluding connections establishing)
tps = 28464.517261 (excluding connections establishing)
tps = 28505.178616 (excluding connections establishing)
tps = 28414.275662 (excluding connections establishing)
tps = 28648.103349 (excluding connections establishing)
The patch seems to average out slightly faster on those runs, but the
variance is around the noise level.
--
David Rowley http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
