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Practical use of ESDS and RRDS VSAM files

 
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Abijoy

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Joined: 24 Mar 2010
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Location: Bangalore

PostPosted: Thu Mar 25, 2010 12:59 pm    Post subject: Practical use of ESDS and RRDS VSAM files
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Hi!

We use a KSDS when we need to read the file with a key and a flat file when only a sequential read is required. Can somebody give me some practical situations where we must use ESDS or RRDS file?
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expat

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Joined: 14 Mar 2007
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PostPosted: Thu Mar 25, 2010 1:07 pm    Post subject:
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An ESDS is the VSAM equivilent of a flat file, but with the added benefit of being able to utilise an alternate index to access the data in addition to sequential access.

RRDS is the VSAM equivilent of a DA file, and in all of my years in IT have rarely encountered the beast except for proprietry software packages.
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Abijoy

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PostPosted: Thu Mar 25, 2010 4:15 pm    Post subject: Reply to: Practical use of ESDS and RRDS VSAM files
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Thanks for the quick reply expat.
I am just curious to know in what situation is an ESDS preffered, rather than a flat file or a KSDS.
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expat

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PostPosted: Thu Mar 25, 2010 4:24 pm    Post subject:
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That depends on the application requirements.
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Robert Sample

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PostPosted: Thu Mar 25, 2010 5:02 pm    Post subject:
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A CICS application that is recording log-type data would be one case where an ESDS file would make sense.
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Nainesh A Jadwani

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PostPosted: Sun Feb 03, 2013 7:34 pm    Post subject: Reply to: Practical use of ESDS and RRDS VSAM files
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Hi,


I too was looking for examples of practical uses of RRDS VSAM files. Didn't find much on the net except for this PowerPoint presentation. (Note to Moderator: hopefully not any copyright issue? PPT is quite freely accessible in my google search).

It, basically, explains that the most appropriate use of an RRDS would be when there is an obvious relationship between your record key and your record's RRN. For example, if you are a telephone company that needs a customer file by telephone numbers. Or if you are a bank that needs customer files by SSN.

A randomizing algorithm would need to be used to avoid large areas of empty RRDS slots for the above cases. All very nicely explained in the above link.

Thought of adding it to this post in case other folks (like Abijoy and myself) are curious about this 'beast'. icon_smile.gif


Thank you,
Nainesh A Jadwani
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enrico-sorichetti

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PostPosted: Sun Feb 03, 2013 7:39 pm    Post subject: Reply to: Practical use of ESDS and RRDS VSAM files
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any reason to resurrect a 3 Years old topic ??? icon_cool.gif

and anyway the examples You described are just examples of RYO data bases ...

and it is quite a few years that they are not fashionable any more
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