Re: Load Distributed Checkpoints, revised patch - Mailing list pgsql-patches

From Heikki Linnakangas
Subject Re: Load Distributed Checkpoints, revised patch
Date
Msg-id 46751432.2010300@enterprisedb.com
Whole thread Raw
In response to Re: Load Distributed Checkpoints, revised patch  ("Simon Riggs" <simon@2ndquadrant.com>)
Responses Re: Load Distributed Checkpoints, revised patch
List pgsql-patches
Simon Riggs wrote:
> On Sun, 2007-06-17 at 08:51 +0100, Heikki Linnakangas wrote:
>>> Do we need to know it so exactly that we look
>>> at WALInsertLock? Maybe use info_lck to request the latest page, since
>>> that is less heavily contended and we need never wait across I/O.
>> Is there such a value available, that's protected by just info_lck? I
>> can't see one.
>
> XLogCtl->LogwrtRqst.Write

That's the Write location. checkpoint_segments is calculated against the
Insert location. In a normal OLTP scenario they would be close to each
other, but if you're doing a huge data load in a transaction; restoring
from backup for example, they could be really far apart.

--
   Heikki Linnakangas
   EnterpriseDB   http://www.enterprisedb.com

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