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VSAM - calculate the RECSZ for alt index

 
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ShwetaG

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Joined: 26 May 2010
Posts: 5
Location: Pune

PostPosted: Fri Feb 18, 2011 1:32 pm    Post subject: VSAM - calculate the RECSZ for alt index
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Hello..Can you please look and advice.

If RECSZ of base cluster for KSDS is changed. How will it impact the RECSZ of the alternate index for the same base ksds cluster. If in case it impacts the alternate index RECSZ then how will we calculate the RECSZ for alt index.





For examplet:



RECSZ(259,259) for KSDS cluster changed to



RECSZ(268,268) .



currently Alter index record length is RECSZ(259,130400).How should we change this

record length corresponds to above base cluster record length.


Thanks.
ShwetaG.
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expat

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Joined: 14 Mar 2007
Posts: 8593
Location: Back in jolly old England

PostPosted: Fri Feb 18, 2011 1:45 pm    Post subject:
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What happened when you tried it out with no changes.

Have you read the IDCAMS manual to see how to calculate the RECSZ for an AIX

These are things that you SHOULD have done before posting.
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Robert Sample

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Joined: 06 Jun 2008
Posts: 8117
Location: East Dubuque, Illinois, USA

PostPosted: Fri Feb 18, 2011 3:46 pm    Post subject:
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You DO realize, I hope, that the record size for an alternate index has absolutely no relationship to the base cluster record size? If you read the manual (Access Method Services for Catalogs, accessible from the manuals link at the top of the page) about DEFINE ALTERNATEINDEX you will learn much and be able to answer your own questions.
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ShwetaG

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Joined: 26 May 2010
Posts: 5
Location: Pune

PostPosted: Fri Feb 18, 2011 5:43 pm    Post subject:
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Thanks Expat and Robert for coming back.

To calculate the record sixe of the AIX we use the formula:
RECSZ = 5 + AIXKL + (n x BCKL) where where:

- RECSZ is the average record size.

- AIXKL is the alternate-key length (see the KEYS parameter).

- BCKL is the base cluster's prime-key length (you can issue the
access method services LISTCAT command to determine the base
cluster's prime-key length).

- n = 1 when UNIQUEKEY is specified (RECSZ is also the maximum
record size).

- n = the number of data records in the base cluster that contain
the same alternate-key value, when NONUNIQUEKEY is specified.


So in the above formula we dont use the RECORD SIZE OF THE PRIMARY key so that also proofs that we don't need to change the RECSZ of AIX if we are changing RECSZ for base cluster.Only if we are changind the keys lenght then we require RECSZ to be changed for AIX.

Thanks again.
ShwetaG.
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