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Can we specify a key in a GSAM file

 
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Verma,Raman

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Joined: 13 Oct 2006
Posts: 15

PostPosted: Fri Feb 16, 2007 2:58 pm    Post subject: Can we specify a key in a GSAM file
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Hi ,

Can we have a key in a GSAM file.

I have to read a large volume of data into a GSAM file in a program that employs check pointing. I want to access this data in a random fashion in the subsequent steps.
Can a GSAM file have a key and can we access it with a GU call using the key?

The problem why I am not trying out VSAM is that I donot want to repeat the copy process in case I get an abend.

Thanks...
Raman
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dick scherrer

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Joined: 23 Nov 2006
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PostPosted: Sat Feb 17, 2007 2:43 am    Post subject:
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Hello,

If the dsorg for your GSAM file is PS, you cannot. Physical Sequential files have no keying mechanism.

I'd use VSAM for the random processing requirement and you can define as many keys as you need to support the processes that run after the first completes.
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superk

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Joined: 26 Apr 2004
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PostPosted: Sat Feb 17, 2007 2:49 am    Post subject: Re: Can we specify a key in a GSAM file
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I found these bullet items in the document Application Programming: Database Manager:


  • An IMS program can retrieve records and add records to the end of the GSAM database, but the program cannot delete or replace records in the database.
  • You use separate calls to access GSAM databases. (Additional checkpoint and restart considerations are involved in using GSAM.)
  • Your program must use symbolic CHKP and XRST calls if it uses GSAM. Basic CHKP calls cannot checkpoint GSAM databases.
  • When an IMS program uses a GSAM data set, the program treats it like a sequential nonhierarchic database. The MVS access methods that GSAM can use are BSAM on direct access, unit record, and tape devices; and VSAM on direct-access storage. VSAM data sets must be nonkeyed, non indexed, entry-sequenced data sets (ESDS) and must reside on DASD. VSAM does not support temporary, SYSIN, SYSOUT, and unit-record files.
  • Because GSAM is a sequential nonhierarchic database, it has no segments, no keys, and no parentage.
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Verma,Raman

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Joined: 13 Oct 2006
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PostPosted: Mon Feb 19, 2007 10:39 am    Post subject: Re: Can we specify a key in a GSAM file
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Hi Superk and Dick Scherrer,

Your guidance was really helpful.I have been able to find a lateral path to my problem because of the timely help.

Thanks...
Raman
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dick scherrer

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PostPosted: Tue Feb 20, 2007 1:20 am    Post subject:
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You're welcome.
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