RE: RE: Optimizing File I-O in RPG IV/ I-Series

I think the actual number is 131,072.

The buffer is 128K.  1 kilobyte = 1,024 bytes.  1,024 * 128 = 131,072. 

I usually use 128,000 though as it's easier to remember.

Rick

-----Original Message-----
From: rpg400-l-bounces@xxxxxxxxxxxx
[mailto:rpg400-l-bounces@xxxxxxxxxxxx]On Behalf Of Tony Carolla
Sent: Wednesday, November 30, 2005 1:41 PM
To: RPG programming on the AS400 / iSeries
Subject: Re: RE: Optimizing File I-O in RPG IV/ I-Series


You know, I hate to nit-pick (I have been called a tweeker before), but this
confuses me.  It says in the article that 128k (131072 bytes) is the size of
a single I/O, and you should set the block size to the number of records
that would fit in this size (I wrote a VB to calc it, BTW).  But then it
shows the formula, and uses 128,000 as the number to use in the
calculation.  I know, I know, we are arguing about 1K (1024 bytes), but what
is the right answer?  I usually use 128000, because I am not sure, and I
figure it is better to not spill over (which could be a throwback to my
high-school job in the coffee shop).

So what is the answer, 128000 or 131027?

On 11/30/05, Hewitt, Rory <rory.hewitt@xxxxxx> wrote:
>
> Kurt wrote:
>
> >Nevermind... Just saw Rory's followup email.
>
> Kurt, I should have said that the ODP buffer size on RISC boxes is 128K
> (rather than the 32K used on CISC boxes). OS/400 only uses the first 4K of
> the buffer when it does its default blocking, so they 'waste' 124K of usable
> buffer space on a RISC box...!
>
> Therefore you should use:
>
> OVRDBF...SEQOBLY(*YES blocking-number)
>
> where blocking-number = (131072 / physical-file-record-length) and round
> that down. Of course the IBM article explains it much better than me
> (including the fact that
>
> HTH,
>
> Rory
>

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