On 07/13/2017 04:36 PM, Adrien Nayrat wrote:
> Hello hackers,
>
> From: Peter Geoghegan <pg@bowt.ie>
>> Date: Wed, 5 Jul 2017 15:19:57 -0700
>> Subject: Re: [BUGS] BUG #14722: Segfault in tuplesort_heap_siftup, 32 bit overflow
>> On pgsql-bugs@postgresql.org
>
> On 07/06/2017 12:19 AM, Peter Geoghegan wrote:
>> In Postgres 10, tuplesort external sort run merging became much faster
>> following commit 24598337c8d. It might be noticeable if such a machine
>> were using Postgres 10 [...]
>
> Should-we mention this improvement in release notes?
>
> Regards,
>
Hello,
After seeing theses slides (especially 52) :
https://speakerdeck.com/peterg/sort-hash-pgconfus-2017
I noticed several commits which improves performance of hash tables. Commit's
messages mentions performance improvements for bitmap scans, hash aggregation
and (according to Peter Geoghegan's conference) hash join :
commit b30d3ea824c5ccba43d3e942704f20686e7dbab8
Author: Andres Freund <andres@anarazel.de>
Date: Fri Oct 14 16:05:30 2016 -0700
Add a macro templatized hashtable.
[...]
In queries where these use up a large fraction of the time, this has been measured to lead to performance
improvementsof over 100%.
commit 75ae538bc3168bf44475240d4e0487ee2f3bb376
Author: Andres Freund <andres@anarazel.de>
Date: Fri Oct 14 16:05:30 2016 -0700
Use more efficient hashtable for tidbitmap.c to speed up bitmap scans.
[...]
For bitmap scan heavy queries speedups of over 100% have been measured.
commit 5dfc198146b49ce7ecc8a1fc9d5e171fb75f6ba5
Author: Andres Freund <andres@anarazel.de>
Date: Fri Oct 14 17:22:51 2016 -0700
Use more efficient hashtable for execGrouping.c to speed up hash aggregation.
[...]
Improvements of over 120% have been measured.
Should we mention it ?
Regards,
--
Adrien NAYRAT
http://dalibo.com - http://dalibo.org