Re: PG 10 release notes

On 07/13/2017 04:36 PM, Adrien Nayrat wrote:
> Hello hackers,
>
> From: Peter Geoghegan <pg(at)bowt(dot)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(at)postgresql(dot)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(at)anarazel(dot)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 improvements of over 100%.

commit 75ae538bc3168bf44475240d4e0487ee2f3bb376
Author: Andres Freund <andres(at)anarazel(dot)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(at)anarazel(dot)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

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