Re: Changing database to SQL from DDS

Simple answer .. 

Single level store means (essentially) that the physical configuration
of the storage is hidden from all of the system except for those OS
routines associated with disk I/O.

Blocking is similar in concept to cacheing . . . even though a program
will read one record at a time, a "block" of records is brought into the
job memory area, speeding the the program access to the individual
records.

Hope this helps.

>>> james@eaerich.com 01/08/03 03:54PM >>>
On Wed, 8 Jan 2003, Leif Svalgaard wrote:

> excuse me, but isn't the Single Level Store supposed to make all
this
> talk about blocking irrelevant? We used to hear that "traditional
> computers" were worse than SLS because data had to transferred
> from the disk into blocks of memory before being processed. SLS was
> supposed to make that obsolete. No?

Old 36 code has a lot of blocking parms in it, so blocking apparently
made
a difference.  When disk is read it is read into something, that
something
is unlikely to be the CPU cache, even on a single level store system. 
The
CPU can't do its work directly on the disk or even directly on the
RAM.
The read operation must store what it reads from disk somewhere where
the
cpu can merge the data with the instruction stream and then execute.

James Rich

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