Skip site navigation (1) Skip section navigation (2)

Re: Streaming replication on win32, still broken

From: Magnus Hagander <magnus(at)hagander(dot)net>
To: Fujii Masao <masao(dot)fujii(at)gmail(dot)com>
Cc: Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Streaming replication on win32, still broken
Date: 2010-02-18 11:14:50
Message-ID: 9837222c1002180314g56e82fd0g472845ed28b6deec@mail.gmail.com (view raw or flat)
Thread:
Lists: pgsql-hackers
2010/2/18 Fujii Masao <masao(dot)fujii(at)gmail(dot)com>:
> On Thu, Feb 18, 2010 at 7:04 PM, Heikki Linnakangas
> <heikki(dot)linnakangas(at)enterprisedb(dot)com> wrote:
>> Magnus Hagander wrote:
>>> O_DIRECT helps us when we're not going to read the file again, because
>>> we don't waste cache on it. If we are, which is the case here, it
>>> should be really bad for performance, since we actually have to do a
>>> physical read.
>>>
>>> Incidentally, that should also apply to general WAL when archive_mdoe
>>> is on. Do we optimize for that?
>>
>> Hmm, no we don't. We do take that into account so that we refrain from
>> issuing posix_fadvice(DONTNEED) if archive_mode is on, but we don't
>> disable O_DIRECT. Maybe we should..
>
> Since the performance of WAL write is more important than that of WAL
> archiving in general, that optimization might offer little benefit.

Well, it's going to make the process that reads the WAL cause actual
physical I/O... That'll take a chunk out of your total available I/O,
which is likely to push you to the limit of your I/O capacity much
quicker.

-- 
 Magnus Hagander
 Me: http://www.hagander.net/
 Work: http://www.redpill-linpro.com/

In response to

Responses

pgsql-hackers by date

Next:From: Fujii MasaoDate: 2010-02-18 11:37:18
Subject: Re: Re: [COMMITTERS] pgsql: Make standby server continuously retry restoring the next WAL
Previous:From: Heikki LinnakangasDate: 2010-02-18 11:14:15
Subject: Re: Streaming replication and unfit messages

Privacy Policy | About PostgreSQL
Copyright © 1996-2014 The PostgreSQL Global Development Group