Re: [MI400] Read and write performance Records VS Fields

["sas" <sas@xxxxxxxxxx>]

Thank you guys,
" Before I blind , But I can see now "
Regards,
Sas

----- Original Message -----
From: "Gary Guthrie" <garyguthrie@charter.net>
To: "MI Programming on the AS400 / iSeries" <mi400@midrange.com>
Sent: Thursday, January 23, 2003 11:43 AM
Subject: Re: [MI400] Read and write performance Records VS Fields

> The reasonable response would have indicated that the question was too
> broad and general for a specific answer. In other words - it depends.
>
> Regarding the O/S handling caching correctly - caching may not even be
> an option to the O/S, depending on access method and such.
>
> The reasonable response would also mention hardware rather than software
> issues. Disk access involves actual moving parts. In other words -
> relatively slow.
>
> I think it reasonable to say that it is basically preposterous to think
> that 100 reads of small amounts of data would ever perform BETTER than 1
> read of all the data. At most, I'd say performance characteristics would
> be identical. Unless, of course, the code that governs the movement of
> data (and I suppose device microcode for DASD, too) is written such that
> it's goal is to devise a scheme where 100 reads would perform better
> than 1 for whatever perverted reason!
>
> Gary Guthrie
>
> Leif Svalgaard wrote:
> >
> > well, it is the same number of bytes to be read, so if the
> > O/S handles caching correctly it shouldn't matter (as the
> > time to make 100 calls vs. one call can be neglected).
> > But the original question was a bit silly (sorry sas).
> > Without information about record sizes, field sizes, how
> > many times the program will be run, etc., no reasonable
> > answer can be given.
>
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