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| Date: | Fri, 3 Mar 2000 13:42:14 -0500 |
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I've just been looking over the blocking-factor messages in the 3000-L archives
and I'm afraid I'm still somewhat confused. It has been claimed that the best
blocking factor can be had by just not specifying one and letting MPE decide.
So I did some testing. Here is a sampling of the results:
BFTEST 1B FA 0 1 128 0 0 *
BFTEST 2B FA 0 1 128 0 0 *
BFTEST 3B FA 0 1 64 0 0 *
BFTEST 5B FA 0 1 42 0 0 *
BFTEST 7B FA 0 1 32 0 0 *
BFTEST 11B FA 0 1 21 0 0 *
BFTEST 17B FA 0 1 14 0 0 *
BFTEST 25B FA 0 1 9 0 0 *
BFTEST 38B FA 0 1 6 0 0 *
BFTEST 57B FA 0 1 4 0 0 *
BFTEST 86B FA 0 1 2 0 0 *
BFTEST 129B FA 0 1 1 0 0 *
BFTEST 194B FA 0 1 1 0 0 *
BFTEST 291B FA 0 1 1 0 0 *
BFTEST 437B FA 0 1 1 0 0 *
BFTEST 656B FA 0 1 1 0 0 *
BFTEST 985B FA 0 1 1 0 0 *
BFTEST 1477B FA 0 1 1 0 0 *
BFTEST 2216B FA 0 1 1 0 0 *
BFTEST 3325B FA 0 1 1 0 0 *
BFTEST 4987B FA 0 1 1 0 0 *
BFTEST 7481B FA 0 1 1 0 0 *
Looks to me like if you don't specify a blocking factor, MPE divides the
sector size (256 bytes) by the record size (adjusted upward to be an even
number if necessary) and drops any fractional portion to get the blocking
factor and that if the calculated number is less than one, it uses one.
Doesn't MPE deal with 4096-byte pages now? Does the blocking factor matter?
How does changing it change the efficiency of the storage or of the retrieval
of the data.
TIA for any answers,
Ted
--
Ted Ashton ([log in to unmask]), Info Sys, Southern Adventist University
==========================================================
The measure of our intellectual capacity is the capacity to feel less and
less satisfied with our answers to better and better problems.
-- Churchman, C. W.
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