Re:

> The performance enhancements achieved by the use of these files is not
> so much the result of them being memory-resident (or not), but rather
> because they can be searched by a binary search algorithm using
> memory-mapped I/O techniques.  In benchmark testing I did, doing lookups

...

Wow...that recalls memories from the past!  We did something like that
for a school back on the Classic HP 3000, around 1985 or so...
and got about a factor of 60 speed improvement.  (I recall that
we averaged 1/2 millisecond with our lookup vs. 30 milliseconds for an
IMAGE DBFIND/DBGET.)  In our case, we used a data segment to hold every nth
record, and then flat files to hold every record.  A binary search of the
data segment told us what file to then binary search.  (Today, of course,
we wouldn't use data segments :)


<plug>
If you want to determine if a file is in memory, the KLONDIKE tool from
Lund Performance Solutions will show you:

   :klondike count foo.pub.sys

   foo.pub.sys @ $699.0:  21 pages; InMem: 0 (0.0% of file, 0.00% of memory)

and, it can fetch it into memory for you:

   :klondike fetch foo.pub.sys

   21 pages; InMem: 21 (100.0% of file, 0.03% of memory); 21 Referenced

</plug>
Stan Sieler                                           [log in to unmask]
www.allegro.com/sieler/wanted/index.html          www.allegro.com/sieler

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