• Subject: Re: buffering
  • From: "Leif Svalgaard" <leif@xxxxxxxx>
  • Date: Sun, 8 Oct 2000 07:47:40 -0500

Thanks Richard,
The info about the option for blocking was just what I needed.
I hope the discussion has also been useful to other people listening
in on the list.
I also have the PRPQ manual, even an 8-inch diskette with the
compiler. Does me little good these days.
My first introduction to MI was Richards article in NEWS/38.
I still have a frayed copy of it.

----- Original Message -----
From: Richard Jackson <richardjackson@richardjackson.net>
To: <MI400@midrange.com>
Sent: Sunday, October 08, 2000 12:32 AM
Subject: RE: buffering

> No pain, no gain.  Except for the System/38-to-RISC hacking, I think we
> the right stuff here.  Create an RPG program to use as a stalking horse for
> offsets and I think we have it.  The block size settings are made as
> structures tagged onto the end of the UFCB before QDMCOPEN is called.  The
> trick is that the data structures are documented in the data areas manual
> the override structure and not documented on the UFCB structure.  It took
> half an hour to remember that.  I'm getting old and stupid.
> In 1984, my first MI program was an MI compiler.  It loaded data from a
> into a user space then called the PRM.  My version used blocked record IO
> and supported conditional nested include files, like C.  It was fairly fast
> .... :)  I never used more than one level of include after that but the
> education was fun.  It t'were a bit harder to write MI in those days that
> is now - no documentation except the PRPQ manual and one had to sign
> and confidentiality agreements to get more information.  My "assistance"
> contact was a private arrangement - he retired from IBM just last April.
> Richard Jackson
> mailto:richardjackson@richardjackson.net
> http://www.richardjacksonltd.com
> Voice: 1 (303) 808-8058
> Fax:   1 (303) 663-4325
> -|-----Original Message-----
> -|From: owner-mi400@midrange.com [mailto:owner-mi400@midrange.com]On
> -|Behalf Of Don
> -|Sent: Saturday, October 07, 2000 9:15 PM
> -|To: MI400 List
> -|Subject: Re: buffering
> -|
> -|Leif,
> -|
> -|Out of curiosity, why are you doing all this torture?  :)
> -|
> -|Don
> -|
> -|On Sat, 7 Oct 2000, Leif Svalgaard wrote:
> -|
> -|> As part of my ongoing investigation of sorting large files,
> -|> I'm reading the files myself into storage to sort them there.
> -|> I have a question about buffering. It doesn't make sense
> -|> that it takes 15 minutes to read 10Mb (1,000,000 records
> -|> of 10 bytes each), so I must not have the right buffering
> -|> set up. What controls that? I was under the (mistaken ?)
> -|> impression that suitable buffering was done by OS/400
> -|> so I don't have to worry about it. If that's the case, it
> -|> is doing a poor job. More likely, I need to do something
> -|> to get better buffering. What?
> -|>
> -|> Leif Svalgaard

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