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.

«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»
«» FlyByNight Software         AS/400 Technical Specialists       «»
«» Eclipse the competition - run your business on an IBM AS/400.  «»
«»                                                                «»
«» Phone: +61 3 9419 0175      Mobile: +61 0411 091 400           «»
«» Fax:   +61 3 9419 0175      mailto: shc@flybynight.com.au      «»
«»                                                                «»
«» Windoze should not be open at Warp speed.                      «»
«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»«»
//--- 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.

+---
| This is the Midrange System Mailing List!
| To submit a new message, send your mail to MIDRANGE-L@midrange.com.
| To subscribe to this list send email to MIDRANGE-L-SUB@midrange.com.
| To unsubscribe from this list send email to MIDRANGE-L-UNSUB@midrange.com.
| Questions should be directed to the list owner/operator: david@midrange.com
+---