Re: "extract" command enhancement (subfiles and BIFs)

[Jim Langston <jlangston@xxxxxxxxxxxxxxxx>]

Hmm... I've noticed something similar when using display on a database file 
(option
5 using PDM).  If I type +10000 on a large file, it takes a long time to move 
to that
record, but if I type in the record number I want to go to directly, it goes 
there almost
instantaneously.

This method does require that you can read an array element (record number) 
almost
immediately, otherwise you will have the problem you described, the OS reads 
every
record from one to what you're looking for, then you give it a new record # and 
it
reads one to this new record number all over again.

How are you reading the 4096th record from your file?

Regards,

Jim Langston

David Morris wrote:

> Jim,
>
> I recently spent some time trying to optimize a page by page subfile 
>positioning
> routine.  I started by reading every 4096th record until I hit a greater key 
>and then
> went back/forth by half until I hit 1 or the key.  Worked pretty good, but it 
>was slower
> than my sequential search which just read every 64th record and then backed up
> when it found a key greater.  I found out that with a scrollable cursor, to 
>get the
> record n records away the system actually performed I/O for all of the inner
> records.  Seems odd to that the system performs I/O when simply counting index
> entries would do.
>
> David Morris

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