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Chinnadu
New User
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Joined: 05 Mar 2009
Posts: 46
Location: Hyderabad
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| Can anyone tell me what is the difference between sequntial data set and a BDAM dataset. |
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dick scherrer
Moderator Emeritus
Joined: 23 Nov 2006
Posts: 19244
Location: Inside the Matrix
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Hello,
BDAM is used for direct access rather than sequential access.
The millionth record in a 5million record file can be read in one read rather than reading all of the records before it. |
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Terry Heinze
JCL Moderator
Joined: 14 Jul 2008
Posts: 1249
Location: Richfield, MN, USA
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| Also, BDAM is no longer supported by COBOL. It's function, for the most part, has been replaced by RRDS VSAM files. Some vendors still use it. I think Panvalet files are BDAM. Also, I think IAM files, although simulating VSAM, are actually BDAM files. |
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dick scherrer
Moderator Emeritus
Joined: 23 Nov 2006
Posts: 19244
Location: Inside the Matrix
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Hello,
The biggest use of BDAM that i've seen is in various database products. |
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Chinnadu
New User
Joined: 05 Mar 2009
Posts: 46
Location: Hyderabad
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Hi All,
Thank you very much for your clarifications, I have one more doubt.
What is the difference between BDAM and VSAM , functionality of both looks similar to me. Is there any difference.Please clarify. |
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Terry Heinze
JCL Moderator
Joined: 14 Jul 2008
Posts: 1249
Location: Richfield, MN, USA
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| Virtual Storage Access Method files can be Entry Sequenced Data Sets (similar to BSAM or QSAM), Relative Record Data Sets, Key Sequenced Data Sets (similar to the old ISAM files), or Linear Data Sets. Basic Direct Access Method files are most like RRDS. Google is your friend. |
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Anuj Dhawan
Superior Member
Joined: 22 Apr 2006
Posts: 6250
Location: Mumbai, India
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| Optionally, BDAM uses hardware keys. Hardware keys are less efficient than the optional software keys in virtual sequential access method (VSAM). |
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dick scherrer
Moderator Emeritus
Joined: 23 Nov 2006
Posts: 19244
Location: Inside the Matrix
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Hi Anuj,
| Quote: |
| Hardware keys are less efficient than the optional software keys in virtual sequential access method (VSAM). |
Maybe (i've not heard that particular thought before), but bdam (in every case that i've worked with) far outperforms vsam . . . |
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Terry Heinze
JCL Moderator
Joined: 14 Jul 2008
Posts: 1249
Location: Richfield, MN, USA
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| Quote: |
| ...bdam (in every case that i've worked with) far outperforms vsam . . . |
When I worked at a shop that converted from OS/VS COBOL to COBOL II, and therefore BDAM to RRDS VSAM, the BDAM files that some folks were used to had to be "pried from their cold, dead hands".  |
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