Re: Re: Faster CREATE DATABASE by delaying fsync (was 8.4.1 ubuntu karmic slow createdb)

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Tue, 29 Dec 2009, Andres Freund wrote:

On Tuesday 29 December 2009 01:30:17 david@xxxxxxx wrote:
On Tue, 29 Dec 2009, Greg Stark wrote:
On Mon, Dec 28, 2009 at 10:54 PM, Andres Freund <andres@xxxxxxxxxxx>
wrote:
fsync everything in that pass.
Including the directory - which was not done before and actually might
be necessary in some cases.

Er. Yes. At least on ext4 this is pretty important. I wish it weren't,
but it doesn't look like we're going to convince the ext4 developers
they're crazy any day soon and it would really suck for a database
created from a template to have files in it go missin.

actually, as I understand it you need to do this on all filesystems except
ext3, and on ext3 fsync is horribly slow because it writes out
_everything_ that's pending, not just stuff related to the file you do the
fsync on.
I dont think its all filesystems (ext2 should not be affected...), but generally
youre right. At least jfs, xfs are affected as well.

ext2 definantly needs the fsync on the directory as well as the file (well, if the file metadata like size, change)

Its btw not necessarily nearly-safe and slow on ext3 as well (data=writeback).

no, then it's just unsafe and slow ;-)

David Lang

--
Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-performance

[Postgresql General]     [Postgresql PHP]     [PHP Users]     [PHP Home]     [PHP on Windows]     [Kernel Newbies]     [PHP Classes]     [PHP Books]     [PHP Databases]     [Yosemite]

  Powered by Linux