Re: Pre-Allocate tablespace on disk

Not only that, but if your "disk" is really a bunch of disks behind a hardware RAID controller, or SAN, or iSCSI or NFS server - what is contiguous for the OS may not be contiguous on the physical drives (and vice versa).
Which is why performance can (but may not) improve if you disable linux kernel IO schedulers that attempt to optimize blocks to be sequential.



On 11/19/2010 5:01 AM, Florian Weimer wrote:

* Chris Ruprecht:

Other database that I have worked with before and that I'm still
working with, allow you to pre-allocate disk space so you get huge
chunks of contiguous space at one, which has major impacts on
database performance.

PostgreSQL's write patterns do not trigger significant fragmentation
with most file systems, even when other database systems (Oracle
Berkeley DB comes to my mind) would create heavily fragmented files.