Date:         Tue, 20 Nov 2001 01:32:28 +0000
Reply-To:     Puddin' Man <pudding_man@POSTMARK.NET>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         Puddin' Man <pudding_man@POSTMARK.NET>
Subject:      Re: Second cousin, once removed, of Speed of SAS vs. COBOL vs.
Comments: To: Larry Bertolini <bertolini.1@OSU.EDU>
Content-Type: text/plain; charset="iso-8859-1"

Larry Bertolini wrote:

> Puddin' Man wrote:
>
> > The curious, curious fella that I am, of course, hadda
> > do exactly that.
> >
> > For your /* pair 1 */ I got  673 EXCP's.
> >
> > For your /* pair 2 */ I got   1291 EXCP's.
> >
> > What EXCP count would you expect if SAS
> > transferred only one 175 b. record from
> > DASD to memory? 1? 3?? 5???
> >
> > Direct access to a flat-file record with SAS?
> > This po' boy remains unconvinced.
> >
> >   Puddin'
>
> OK, on the unlikely chance that anyone cares,
> here are my EXCP counts for my tests:
>
> INFILE/INPUT method:     #records skipped  EXCPs   CPU time of SAS step
> --------------------     ----------------  -----   --------------------
> RECFM=N; INPUT @1750001    10,000            1     0.22 sec
> FIRSTOBS=10001             10,000           67     0.25 sec
> RECFM=N; INPUT @17500001  100,000            1     0.22 sec
> FIRSTOBS=100001           100,000          633     0.42 sec
>
> Note that I am counting EXCPs only to the file referenced by
> the INFILE; I'm not counting EXCPs to other datasets.
> (Data gathered from SMF Type 14 records.)
>
> The EXCP counts for the "FIRSTOBS=n" tests are relatively
> consistent with my expectation (LRECL=175,BLKSIZE=27825,
> 159 records per block).  SAS appears to start reading from
> the beginning of the file, and discarding records before the
> FIRSTOBS record.
>
> The EXCP counts for the "RECFM=N" tests suggest (to me,
> anyway) that SAS is going directly to the desired record.

Larry,

Your EXCP counts differ from mine.

I'm not even certain why we are testing.

What is SAS doing in reading your flat-file? QSAM??

From the Onlindoc:

--------------------------------------------------------------
RECFM=record-format
specifies the record format of the file. Valid values are :

N - indicates that the file is in binary format. The file is treated
as  a byte stream; that is, line boundaries are not recognized. This record
format is specific to the SAS System.
--------------------------------------------------------------

If "the file is treated as a byte stream", I frankly and
in the context of OS/390 access methods don't know _how_
SAS could read the Nth byte without transferring the first
N-1 b. from DASD to memory. No doubt you can enlighten po'
me (please include all the gory details <g>).

  Cheers,
  Puddin'