[Info-vax] Databases versus RMS

[Paul Sture]

On Wed, 18 Apr 2012 08:57:16 -0400, David Froble wrote:

> If Cobol is doing a deferred write, ie; don't write the buffer until
> necessary, then that is NOT a "write to disk".

I've used COBOL's deferred write in combination with large read buffers 
to good effect for specific tasks, such as for print spool files or 
master file extracts.  If the job doesn't run to completion because of a 
system crash (or heaven forbid an app crash), you would want to rerun the 
entire job anyway.

For good ole batch processing where no vital files are updated, this can 
bring excellent performance gains.

Going back to PDP (and RK05) days, doing your own buffering at the app 
level for large printouts produced significant gains.  Reading in enough 
records in your app to fill an old fashioned 132x64 line printer page 
then zapping that page out in one go could easily cut the run time down 
from 45 or more minutes to 15.  It obviously didn't make sense to go that 
effort for small reports, but for price or stock level lists of 20,000 or 
more items it did.

-- 
Paul Sture