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Re: testing HS/SR - 1 vs 2 performance

From: Dimitri Fontaine <dfontaine(at)hi-media(dot)com>
To: Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>
Cc: Erik Rijkers <er(at)xs4all(dot)nl>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: testing HS/SR - 1 vs 2 performance
Date: 2010-04-14 08:24:45
Message-ID: 87fx2ywieq.fsf@hi-media-techno.com (view raw or flat)
Thread:
Lists: pgsql-hackers
Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com> writes:
>  Changing the KnownAssignedXids data structure from
> hash table into something that's quicker to scan. Preferably something
> with O(N), where N is the number of entries in the data structure, not
> the maximum number of entries it can hold as it is with the hash table
> currently.

So that's pretty good news RedBlack Trees made it in 9.0, isn't it? :)

> A quick fix would be to check if there's any entries in the hash table
> before scanning it. That would eliminate the overhead when there's no
> in-progress transactions in the master. But as soon as there's even one,
> the overhead comes back.

Does not sound like typical, does it?
-- 
dim

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