On Thu, Aug 31, 2017 at 10:46 PM, Simon Riggs <simon@2ndquadrant.com> wrote:
> On 31 August 2017 at 17:48, Robert Haas <robertmhaas@gmail.com> wrote:
>
>> I would argue for
>> adding Andres's executor speedups and Amit's hash index work, too
>
> Do we have accepted/verified perf results we can quote?
>
The main benefit (as mentioned by Robert) of hash indexes is that now
they are durable, but they do better than btree indexes in some use
cases (in terms of size and raw TPS) as has been demonstrated with the
help of real world workload and by doing performance testing using
benchmark pgbench. Just to give some references, please see the posts
of some of the users on hackers.
Reference about size:
https://www.postgresql.org/message-id/20170704105728.mwb72jebfmok2nm2%40zip.com.au
Reference about the performance of Select:
https://www.postgresql.org/message-id/4575a870-1315-18ac-0516-c21a83a7afdf%40redhat.com
Apart from above, I and some of my colleagues have also done
performance testing, the results of which are summarized in my PGCon
presentation:
https://www.pgcon.org/2017/schedule/events/1039.en.html
Now, I don't want to say that hash indexes became better in terms of
size and performance only because of work in PG-10. However, there
has been substantial work done in PG-10 in both areas and the numbers
have been shared on hackers (in case you or others want to see, I can
dig down those emails and share it here).
I am not sure whether the work done on hash indexes in PG-10 makes it
a candidate for the major feature, but I think it is worth
considering.
--
With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com