At 09:26 AM 9/19/01 -0400, Alexandre Kozlov wrote:

>Hi ALL,
>
>I just want to add that 'natural order' (or any other one) is much more
>effective when we
>explicitly get benefits from underlying software/hardware engine layer. In
>this vision
>it seemed 'read ahead' brings undoubtly great acceleration. I tested this
>approach on very
>large DB to speed up scannig operation drastically on main table.
>

Absolutely correct.

The precursor system to Interbase, Rdb/ELN, was designed to run
inside DEC's HSC disk controller. One of the goals of the index
handling schema was to be able to indentify all pages required
for a request, ask for them asynchronously, and handle the pages
as they showed. We never got that far, and with the possible
exception of VMS, no operating system delivers pages asynchronously
in order of convenience, so the feature has been been used.

Unfortunately, to exploit the feature, the super-server crap
would need to be ripped out and reimplemented with light weight
threads, not a easy undertaking.

Jim Starkey