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Re: Hot standby and GiST page splits (was Re: WIP: Fast GiST index build)

From: Simon Riggs <simon(at)2ndQuadrant(dot)com>
To: Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>
Cc: Alexander Korotkov <aekorotkov(at)gmail(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Hot standby and GiST page splits (was Re: WIP: Fast GiST index build)
Date: 2011-08-01 15:25:01
Message-ID: CA+U5nMJKRte51t3zdjnOpBTFVDjBfBKZ8zQy87EDH3s7nkLUvw@mail.gmail.com (view raw or flat)
Thread:
Lists: pgsql-hackers
On Mon, Aug 1, 2011 at 3:34 PM, Heikki Linnakangas
<heikki(dot)linnakangas(at)enterprisedb(dot)com> wrote:
> On 01.08.2011 17:26, Simon Riggs wrote:
>>
>> On Mon, Aug 1, 2011 at 2:29 PM, Heikki Linnakangas
>> <heikki(dot)linnakangas(at)enterprisedb(dot)com>  wrote:
>>>
>>> I believe we code acquire the locks in right order already, and the patch
>>> I
>>> posted fixes the premature release of locks at page split.
>>
>> Your patch is good, but it does rely on the idea that we're logging
>> the blocks in the same order they were originally locked. That's a
>> good assumption, but I would like to see that documented for general
>> sanity, or just mine at least.
>>
>> I can't really see anything in the master-side code that attempts to
>> lock things in a specific sequence, which bothers me also.
>
> All but the first page are unused pages, grabbed with either P_NEW or from
> the FSM. gistNewBuffer() uses ConditionalLockBuffer() to guard for the case
> that someone else chooses the same victim buffer, and picks another page.

Seems good. Thanks for checking some more for me.

-- 
 Simon Riggs                   http://www.2ndQuadrant.com/
 PostgreSQL Development, 24x7 Support, Training & Services

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