Horton

Re: Small improvement to compactify_tuples

Peter Geoghegan <pg@bowt.ie>

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From: Peter Geoghegan <pg@bowt.ie>
To: Юрий Соколов <funny.falcon@gmail.com>
Cc: Tom Lane <tgl@sss.pgh.pa.us>, Andres Freund <andres@anarazel.de>, Claudio Freire <klaussfreire@gmail.com>, Sokolov Yura <funny.falcon@postgrespro.ru>, Alvaro Herrera <alvherre@2ndquadrant.com>, Heikki Linnakangas <hlinnaka@iki.fi>, PostgreSQL-Dev <pgsql-hackers@postgresql.org>
Date: 2017-11-07T22:50:38Z
Lists: pgsql-hackers 
On Tue, Nov 7, 2017 at 2:40 PM, Юрий Соколов <funny.falcon@gmail.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

Commits

  1. Avoid looping through line pointers twice in PageRepairFragmentation().

  2. Reduce pinning and buffer content locking for btree scans.

  3. Speed up in-memory tuplesorting.