| From: | Peter Geoghegan <pg(at)bowt(dot)ie> |
|---|---|
| To: | Юрий Соколов <funny(dot)falcon(at)gmail(dot)com> |
| Cc: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Andres Freund <andres(at)anarazel(dot)de>, Claudio Freire <klaussfreire(at)gmail(dot)com>, Sokolov Yura <funny(dot)falcon(at)postgrespro(dot)ru>, Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>, Heikki Linnakangas <hlinnaka(at)iki(dot)fi>, PostgreSQL-Dev <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Small improvement to compactify_tuples |
| Date: | 2017-11-07 22:50:38 |
| Message-ID: | CAH2-WzkV3t4Y--RLoFCmeGL6ktPLFgdMyFyEc8yea2hTf6=AqA@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Tue, Nov 7, 2017 at 2:40 PM, Юрий Соколов <funny(dot)falcon(at)gmail(dot)com> wrote:
>> The same is true of unique indexes vs. non-unique.
>
> offtopic: recently I'd a look at setting LP_DEAD in indexes.
> I didn't found huge difference between unique and non-unique indices.
> There is codepath that works only for unique, but it is called less
> frequently than common codepath that also sets LP_DEAD.
I meant to say that this is only important with UPDATEs + contention.
The extra LP_DEAD setting within _bt_check_unique() makes quite a
noticeable difference, at least in terms of index bloat (though less
so in terms of raw TPS).
--
Peter Geoghegan
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