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Does Path have a copy of base data

 
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sumithar
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Joined: 22 Sep 2006
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PostPosted: Wed Jul 31, 2019 3:48 pm    Post subject: Does Path have a copy of base data Reply with quote

Excuse me for asking such a basic question...

When I create an AIX and path for a VSAM dataset does the path have a copy of the base data but sorted in the order of the AIX? I did fair bit of googling but most sites just say that for each AIX you need to define a Path w/o specifying what exactly is in the Path.

When I browse the Path I can indeed see that the same records exist but in the order of the AIX.
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kolusu
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PostPosted: Wed Jul 31, 2019 5:52 pm    Post subject: Reply with quote

sumithar,

In simple terms Path is nothing but an alias to AIX. when you refer to the path , it is actually referring to the AIX as well the base cluster associated with it. If you did a LISTCAT ALL ENTRY('Your Path Name') and in the output look for "Associations" and you will notice that the PATH has related all component parts of the alternate index cluster and the base record cluster.

Here is the actual definition of the Path from "VSAM Demystified"

Before you access a KSDS or ESDS through an alternate index, a path must be defined in the catalog. A path is the means by which a base cluster is accessed through its alternate indexes. A path is defined and named by using the IDCAMS DEFINE PATH command. At least one path must be defined for each of the alternate indexes through which they access the base cluster. The path name refers to the base cluster and alternate index pair. When a program opens a path for processing, both the base cluster and the alternate index are opened. A base cluster plus all its AIX is called a sphere.
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sumithar
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Joined: 22 Sep 2006
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PostPosted: Thu Aug 01, 2019 7:48 am    Post subject: Reply with quote

Thank you, that clears it up well. I did download VSAM DeMystified but evidently didn't read it properly. bonk
So just to confirm, if I choose to view the Path via the File Manager product, say, I am seeing a "view" of the base data that has been reordered on the fly in the sequence of the AIX.
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