On Mon, 2005-10-31 at 16:34, Tomeh, Husam wrote:
> My understanding that the current release of Postgres does not allow
> the DBA to pre-allocated space for the data files or tablespace in
> advance (as Oracle or SQL Server does). Am I correct on that ? If
> that's still the case, is this item on the TODO list or the white
> board? Pre-allocating space will prevent extending the datafile during
> loading massive data (batch processing) and would improve the overall
> batch write performance.
I can't see pre-allocation making much if any difference in any modern
OS, except it might lower fragmentation of the file a bit. Writing data
is writing data. It takes time, whether you're writing it into a file
that already exists with zeros in it or a new blank file you just
created.
Have you got any file system benchmarks that back up this assertion? I
would love to see something that shows one way or the other if that
really makes any difference.