Re: Read/Write block sizes - Mailing list pgsql-performance

From Jeffrey W. Baker
Subject Re: Read/Write block sizes
Date
Msg-id 1124861121.11270.1.camel@noodles
Whole thread Raw
In response to Re: Read/Write block sizes  (Guy Thornley <guy@esphion.com>)
Responses Re: Read/Write block sizes  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-performance
On Wed, 2005-08-24 at 17:20 +1200, Guy Thornley wrote:
> As for the async IO, sure you might think 'oh async IO would be so cool!!'
> and I did, once, too. But then I sat down and _thought_ about it, and
> decided well, no, actually, theres _very_ few areas it could actually help,
> and in most cases it just make it easier to drive your box into lseek()
> induced IO collapse.
>
> Dont forget that already in postgres, you have a process per connection, and
> all the processes take care of their own I/O.

That's the problem.  Instead you want 1 or 4 or 10 i/o slaves
coordinating the I/O of all the backends optimally.  For instance, with
synchronous scanning.

-jwb


pgsql-performance by date:

Previous
From: Gavin Sherry
Date:
Subject: Re: Caching by Postgres
Next
From: Tom Lane
Date:
Subject: Re: Read/Write block sizes