"VANCE,JEFF (HP-Cupertino,ex1)" wrote:
> From what I know the blocking factor does not matter for disk files
> because MPE reads and pre-fetches their contents into memory and then
> just moves bytes from a memory buffer to your stack.

That's my understanding too.

You can verify it yourself by using :DEBUG to map your files into memory and
then displaying the records with dv.  All records are contiguous with no filler
bytes at all.

> However I seem
> to recall some cases where it may matter, but I am sorry to say I
> have forgotten the details.

One place it might matter is if you're doing MR-NOBUF I/O.  The FREAD intrinsic
can only read a maximum of 32766 (?) bytes at a time, and if you're doing
MR-NOBUF, you read records in block multiples.  So for best MR-NOBUF
performance, you'd want a block size that divides as evenly as possible into
32766.

- Mark B.