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Difference between VSAM and ISAM files

 
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achusarath

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Joined: 21 Mar 2007
Posts: 26
Location: kerala

PostPosted: Mon Apr 16, 2007 4:50 pm    Post subject: Difference between VSAM and ISAM files
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hi,


please tell the difference ISAM and VSAM files
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superk

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Joined: 26 Apr 2004
Posts: 4648
Location: Raleigh, NC, USA

PostPosted: Mon Apr 16, 2007 5:00 pm    Post subject: Re: Difference between VSAM and ISAM files
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Indexed Sequential Access Method.

Virtual Storage Access Method.
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muthuvel

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Joined: 29 Nov 2005
Posts: 217
Location: Chennai

PostPosted: Mon Apr 16, 2007 5:06 pm    Post subject: Re: Difference between VSAM and ISAM files
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this is what the manual says

VSAM

Description: VSAM = Virtual Storage Access Method

a) An access method for direct or sequential processing of
fixed-and variable-length records on direct access
devices. The records in a VSAM data set or file can be
organized in logical sequence by a key field (key
sequence = KSDS), in the physical sequence in which they
are written on the data set or file (entry sequence =
ESDS), or by relative record number (RRDS).


ISAM

Description: ISAM = Indexed Sequential Access Method

An access method that can be used for either direct or
sequential update or retrieval. An index is stored on DASD
with the data set.

ISAM is a non VSAM data set.

If my guess is correct any data file that is sorted on a particular key is ISAM icon_wink.gif

Corrections are welcome..
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expat

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Joined: 14 Mar 2007
Posts: 8593
Location: Back in jolly old England

PostPosted: Mon Apr 16, 2007 5:06 pm    Post subject:
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And ISAM is no longer an access method supported by IBM. I think support for that died out in the 1980's.
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