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A couple of lightning strikes zapped my attempts to reply yesterday. At this
stage I have only a couple of thoughts left ....
In my experience a data step (or SQL) view works like an internal pipe. When
it executes it streams data from sources and directs them to a display or to
another level of a program. It appears to use the same buffers, other memory
caches, and temporary files that ordinary SAS data steps and procedures use.
On that score, as others have said, Biff rules.
Biff's former friend can still argue effectively against using a view in
some situations. Let's say that data updates occur at night, and that during
the day an average of five people per day request a summary by region of a
large set of data. Rather than read and summarize the data set five times
daily, it would make better sense to execute the summary immediately
following each overnight update and store the result as a table instead of a
view.
Views make better sense when data sources can change continuously. In those
cases, creating a work or permanent dataset will serve no particular purpose
and will require more resources.
Sig
-----Original Message-----
From: Biff Henderson [mailto:tango_zebra2002@YAHOO.COM]
Sent: Tuesday, July 23, 2002 4:55 PM
To: SAS-L@LISTSERV.UGA.EDU
Subject: Settle an argument about a view
A colleague of mine insists that when a data step view
is called, SAS creates a full physical copy of the
"view" somewhere in its workspace prior to the next
data step or proc. I say that is not exactly true. I
believe that no output data set is created when the
view is called. I think each output record is fed
into the next data step or proc. (There may be some
temporary datasets built, however).
Her arguments against a view was something like "...
if 5 people call that view at the same time, SAS has
to generate 5 physical copies. Where is that space
savings now...?"
Again, I don't believe this to be true. Can some
straighten us out?
Thanks,
Biff
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