Horton

Re: [HACKERS] GSoC 2017: weekly progress reports (week 6)

Alvaro Herrera <alvherre@alvh.no-ip.org>

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From: Alvaro Herrera <alvherre@alvh.no-ip.org>
To: Teodor Sigaev <teodor@sigaev.ru>
Cc: Dmitry Ivanov <d.ivanov@postgrespro.ru>, Shubham Barai <shubhambaraiss@gmail.com>, Alexander Korotkov <a.korotkov@postgrespro.ru>, Andrey Borodin <x4mmm@yandex-team.ru>, Thomas Munro <thomas.munro@enterprisedb.com>, pgsql-hackers <pgsql-hackers@postgresql.org>, Andrew Borodin <amborodin86@gmail.com>, Kevin Grittner <kgrittn@gmail.com>
Date: 2018-03-29T17:24:46Z
Lists: pgsql-hackers 
Teodor Sigaev wrote:
> 
> Alvaro Herrera wrote:
> > I don't quite understand the new call in gininsert -- I mean I see that
> > it wants to check for conflicts even when fastupdate is set, but why?
> If fastupdate is set then we check conflict with whole index, not a
> particular pages in it. Predicate lock on penging list pages will be
> effectively a lock over index, because every scan will begin from pending
> list and each insert will insert into it. I

Oh, right, that makes sense.  I'm not sure that the comments explain
this sufficiently -- I think it'd be good to expand that.


Given this patch, it seems clear that serializable mode is much worse
with fastupdate than without it!

-- 
Álvaro Herrera                https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

Commits

  1. Re-think predicate locking on GIN indexes.

  2. Predicate locking in GIN index