On 21.2.2015 00:14, Peter Geoghegan wrote: > On Fri, Feb 20, 2015 at 1:33 PM, Tomas Vondra > <tomas.von...@2ndquadrant.com> wrote: >> For example with the same percentile_disc() test as in the other >> thread: >> >> create table stuff as select random()::numeric as randnum from >> generate_series(1,1000000); >> >> analyze stuff; >> >> select percentile_disc(0) within group (order by randnum) from >> stuff; >> >> >> I get pretty much no difference in runtimes (not even for the >> smallest dataset, where the Datum patch speedup was significant). >> >> What am I doing wrong? > > So you're testing both the patches (numeric + datum tuplesort) at the > same time?
No, I was just testing two similar patches separately. I.e. master vs.
each patch separately.
> I can't think why this would make any difference. Did you forget to
> initdb, so that the numeric sortsupport routine was used?
No, but just to be sure I repeated the benchmarks and I still get the
same results. Each test run does this:
1) remove data directory
2) initdb
3) copy postgresql.conf (with minor tweaks - work_mem/shared_buffers)
4) start
5) create database
6) create test table
7) run a query 5x
I repeated this, just to be sure, but nope - still no speedup :-(
For master vs. patch, I do get these results:
master patched speedup
---------------------------------------------------------
generate_series(1,1000000) 1.20 1.25 0.96
generate_series(1,2000000) 2.75 2.75 1.00
generate_series(1,3000000) 4.40 4.40 1.00
So, no difference :(
Scripts attached, but it's really trivial test - hopefully I haven't
done anything dumb.
--
Tomas Vondra http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
reinit.sh
Description: application/shellscript
bench.sh
Description: application/shellscript
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