On Fri, 22 Aug 2003, Mike Mascari wrote:
> In addition to Jan's points, using a single pre-allocated file also
> reduces file descriptor consumption, although I don't know what the
> costs are regarding maintaining the LRU of file descriptors, the price
> of opens and closes, the price of having a high upper limit of file
> descriptors, etc.
>
another thought I had - I wonder how much fragmentation affects postgres
(and others). On Informix when you use "cooked files" it needs to
preallocate all the space. I figured part of it was to 1. make the file
seem more like a device 2. reduce fragmentation 3. guarantee that 2GB
"chunk" can never have an out of space issue.
On a dedicated pg box there is probably not much fragmentation (and thanks
to today's modern filesystems, it isn'ttoo big of a deal in any case)..
but it would still be interesting to have numbers..
--
Jeff Trout <jeff@jefftrout.com>
http://www.jefftrout.com/
http://www.stuarthamm.net/