From: Richard Huxton <dev@archonet.com>
To: Matthew <matthew@flymine.org>
Cc: pgsql-performance@postgresql.org
Subject: Re: Benchmark Data requested
Date: Tue, 05 Feb 2008 16:09:36 +0000
Message-ID: <47A88A40.5090502@archonet.com> (raw)
In-Reply-To: <Pine.LNX.4.64.0802051554010.20402@aragorn.flymine.org>
References: <1202150236.4252.521.camel@ebony.site>
<Pine.GSO.4.64.0802041500460.799@westnet.com>
<47A797E5.4000507@sun.com>
<200802051506.51581.dfontaine@hi-media.com>
<1202221496.4252.680.camel@ebony.site>
<47A87618.1090203@archonet.com>
<1202223268.4252.707.camel@ebony.site>
<Pine.LNX.4.64.0802051523470.20402@aragorn.flymine.org>
<47A8862A.1060205@archonet.com>
<Pine.LNX.4.64.0802051554010.20402@aragorn.flymine.org>
Matthew wrote:
> On Tue, 5 Feb 2008, Richard Huxton wrote:
>>> Why would you need to lock the table?
>>
>> Because you're not really writing the WAL, which means you can't let
>> anyone else get their data into any of the blocks you are writing
>> into. You'd basically want to write the disk blocks then "attach" them
>> in some way.
>
> So what's wrong with "reserving" the space using the WAL, then everyone
> else will know. After all, when you write the data to the WAL, you must
> have an idea of where it is meant to end up. My suggestion is that you
> go through all the motions of writing the data to the WAL, just without
> the data bit.
Well, now you're looking at page-level locking for the data blocks, or
at least something very similar. Not sure what you'd do with indexes
though - don't see a simple way of avoiding a large lock on a btree index.
If you reserved the space in advance that could work. But you don't know
how much to reserve until you've copied it in.
You could of course have a set of co-operating processes all
bulk-loading while maintaining a table-lock outside of the those. It
feels like things are getting complicated then though.
--
Richard Huxton
Archonet Ltd
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Reply to all the recipients using the --to and --cc options:
reply via email
To: pgsql-performance@postgresql.org
Cc: dev@archonet.com, matthew@flymine.org
Subject: Re: Benchmark Data requested
In-Reply-To: <47A88A40.5090502@archonet.com>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox