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Performance issue of VSAM when compared to Table

 
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harry143

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Joined: 05 Nov 2007
Posts: 21
Location: hyd

PostPosted: Thu Mar 13, 2008 5:58 pm    Post subject: Performance issue of VSAM when compared to Table
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Hi,

Please see the below two points:

1) Random search in a VSAM File
2) Storing the VSAM file in an occurs table and Searching in it with the matching fields using perform statement.

Can any body suggest which one is the best when coming to performance issue??
I have a large amount of records to be searched.
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Craq Giegerich

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Joined: 19 May 2007
Posts: 1512
Location: Virginia, USA

PostPosted: Thu Mar 13, 2008 6:02 pm    Post subject:
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It would depend. How many times are you going to be searching the table, how big would the table be, does the vsam file have a key to use for the search?
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harry143

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Joined: 05 Nov 2007
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Location: hyd

PostPosted: Thu Mar 13, 2008 6:08 pm    Post subject:
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Craq Giegerich wrote:
It would depend. How many times are you going to be searching the table, how big would the table be, does the vsam file have a key to use for the search?


The table would be an occurs of 3000.
Yes the VSAm file has the key to search.
for each record nearly two to three times i have to serach.
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Bill O'Boyle

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Joined: 14 Jan 2008
Posts: 2502
Location: Atlanta, Georgia, USA

PostPosted: Thu Mar 13, 2008 6:22 pm    Post subject: Performance issue of VSAM when compared to Table
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If there's someone in your shop that writes Assembler, you could call an Assembler sub-program (which issues a SHOWCB Macro) and it can return the number of records and (if needed) the LRECL of the target VSAM file which you want to load into memory.

Then, you can define your table in LINKAGE, with an OCCURS DEPENDING ON and acquire dynamic storage via the LE Callable Service routine "CEEGTST" or an Assembler sub-program which issues an MVS "GETMAIN".

By doing it this way, you won't have to worry about defining an OCCURS table in WS, which could spill over at 3:00am, causing someone to increase the OCCURS, re-compile the program and cross their fingers.

However, if it spills over once, it will spill over again.

Murphy is alive and well ya know. icon_wink.gif

HTH....

Regards,

Bill
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