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Abijoy
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Joined: 24 Mar 2010
Posts: 12
Location: Bangalore
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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
Global Moderator
Joined: 14 Mar 2007
Posts: 8797
Location: Welsh Wales
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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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Joined: 24 Mar 2010
Posts: 12
Location: Bangalore
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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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Joined: 14 Mar 2007
Posts: 8797
Location: Welsh Wales
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| That depends on the application requirements. |
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Robert Sample
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Joined: 06 Jun 2008
Posts: 8696
Location: Dubuque, Iowa, USA
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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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Joined: 15 Jan 2013
Posts: 6
Location: India
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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'. 
Thank you,
Nainesh A Jadwani |
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enrico-sorichetti
Superior Member
Joined: 14 Mar 2007
Posts: 10873
Location: italy
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any reason to resurrect a 3 Years old topic ??? 
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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