RE: Calculating the number of records parameter for batch extract

[Colin Williams <colin.williams@xxxxxxxxxxxxxxxxx>]

Cheers, just what I needed.
Colin.W

-----Original Message-----
From: Simon Coulter [mailto:shc@flybynight.com.au]
Sent: Sunday, March 26, 2000 12:15 AM
To: MIDRANGE-L@midrange.com
Subject: Re: Calculating the number of records parameter for batch
extract



Hello Colin,

Maximum block size is 32Kb on CISC, 64Kb on RISC (OS version is 
irrelevant).  You 
can, of course, use larger block sizes but they tend to be less 
efficient.

roundDown(BlockingFactor = BlockSize / RecordLength)

Specify the BlockingFactor on the OVRDBF command according to 
the effect you want to 
achieve:

OVRDBF NBRRCDS(BlockingFactor) controls the number of records 
brought from DASD to 
main store.

OVRDBF SEQONLY(*YES BlockingFactor) controls the number of 
records moved from main 
store to program storage (i.e., program record buffer).

NBRRCDS can be used for both sequential and keyed I/O.  SEQONLY 
can only be used for 
sequential I/O.

Sequential I/O + NBRRCDS + SEQONLY = BlindingSpeed

Fastest of all:  Allocate separate storage pool, pre-load the 
object using SETOBJACC, 
and avoid disk I/O entirely.

Simplified for the technically challenged -- a new approach I'm 
trying  :-)

Regards,
Simon Coulter.

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//--- forwarded letter 
-------------------------------------------------------
> X-Mailer: Internet Mail Service (5.0.1459.74)
> Date: Fri, 24 Mar 2000 11:55:08 +0000
> From: "Colin Williams" <colin.williams@technocrats.co.uk>
> To: "'MIDRANGE-L@midrange.com'" <MIDRANGE-L@midrange.com>
> Reply-To: MIDRANGE-L@midrange.com
> Subject: Calculating the number of records parameter for batch extract

> 
> I am running a batch extract on V4R2, and want to set the 
optimum number
> of records to read in using 
> the SEQONLY parameter on OVRDBF. 
> 
> Is it 4K Divided by RCDLEN  or 32K divided RCDLEN? 
> I realise there are other factors to consider, but I am just 
using this
> as a starting point.

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