On Thu, Sep 8, 2016 at 10:41 PM, Ashutosh Bapat <
ashutosh(dot)bapat(at)enterprisedb(dot)com> wrote:
>
>
> I think we should try to measure performance gain because of aggregate
> pushdown. The EXPLAIN
> doesn't show actual improvement in the execution times.
>
I did performance testing for aggregate push down and see good performance
with the patch.
Attached is the script I have used to get the performance numbers along with
the results I got with and without patch (pg_agg_push_down_v3.patch). Also
attached few GNU plots from the readings I got. These were run on my local
VM having following details:
Linux centos7 3.10.0-327.28.3.el7.x86_64 #1 SMP Thu Aug 18 19:05:49 UTC
2016 x86_64 x86_64 x86_64 GNU/Linux
RAM alloted: 8 GB
CPUs alloted: 8
postgresql.conf is default.
With aggregate push down I see around 12x performance for count(*)
operation.
In another test, I have observed that if number of groups returned from
remote server is same as that of input rows, then aggregate push down
performs
slightly poor which I think is expected. However in all other cases where
number of groups are less than input rows, pushing down aggregate gives
better
performance than performing grouping on the local server.
I did this performance testing on my local setup. I would expected even
better
numbers on a specialized high-end performance machine. I would be more than
happy if someone does this testing on such high-end machine.
Let me know if you need any help.
Thanks
--
Jeevan B Chalke
Principal Software Engineer, Product Development
EnterpriseDB Corporation
The Enterprise PostgreSQL Company
