On Tue, Jun 28, 2005 at 12:02:55PM -0500, John A Meinel wrote:
There has been discussion about changing the reading/writing code to be
able to handle multiple pages at once, (using something like vread())
but I don't know that it has been implemented.


that sounds promising

Also, this would hurt cases where you can terminate as sequential scan
early.

If you're doing a sequential scan of a 10G file in, say, 1M blocks I
don't think the performance difference of reading a couple of blocks
unnecessarily is going to matter.

And if the OS is doing it's job right, it will already do some
read-ahead for you.

The app should have a much better idea of whether it's doing a
sequential scan and won't be confused by concurrent activity. Even if
the OS does readahead perfectly, you'll still get a with with larger
blocks by cutting down on the syscalls.

Mike Stone


---------------------------(end of broadcast)---------------------------
TIP 5: Have you checked our extensive FAQ?

              http://www.postgresql.org/docs/faq

Reply via email to