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vch
New User
Joined: 01 Feb 2008 Posts: 16 Location: chennai
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Hi,
how to create alternate index for ESDS..?
what is the difference between QSAM and ESDS?? |
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References
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Posted: Fri Mar 21, 2008 3:21 pm Post subject: Re: How to create alternate index for ESDS |
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Gnanas SNG
Senior Member
Joined: 06 Sep 2007 Posts: 370 Location: India
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I think of these.
Sequential(QSAM) files can be created on tape while ESDS files cannot.
Also, you can have ALTINDEX for an ESDS while no such facility exists for QSAM files.
You can this for creating alternate index.
| Code: |
| DEFINE ALTERNATEINDEX .... |
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dbzTHEdinosauer
Senior Member
Joined: 20 Oct 2006 Posts: 903 Location: germany
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gnanas,
what would be the key? how would you define it? |
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Gnanas SNG
Senior Member
Joined: 06 Sep 2007 Posts: 370 Location: India
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Dick,
Alternate Index Key Type for ESDS may be either Unique key or
Nonunique key
Please correct me if I am worng. |
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Moved: Fri Mar 21, 2008 4:12 pm by mcmillan From JCL to Interview Questions |
vch
New User
Joined: 01 Feb 2008 Posts: 16 Location: chennai
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ganas,
how to define alternate index for ESDS? can you give me full syntax for taht? |
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Gnanas SNG
Senior Member
Joined: 06 Sep 2007 Posts: 370 Location: India
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Marso
Active User
Joined: 13 Mar 2006 Posts: 264 Location: Israel
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| vch wrote: |
Hi,
how to create alternate index for ESDS..? |
An alternate index ??? I'm quite sure you can't even have a primary index on ESDS files... |
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Anuj D.
Senior Member
Joined: 22 Apr 2006 Posts: 1124 Location: Mumbai, India
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Hi,
It seems relevant to have a definition of ESDS here:
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| A VSAM file whose records are loaded without respect to their contents, and whose relative byte addresses (RBAs) cannot change. Records are retrieved and stored by addressed access, and new records are added at the end of the file. |
And from Your link gnanas
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| The NONINDEXED keyword causes an ESDS to be defined. |
I hope you got the pointer why there are disagreement about Your post. And yes RBA is not INDEX. |
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Anuj D.
Senior Member
Joined: 22 Apr 2006 Posts: 1124 Location: Mumbai, India
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Hi,
A little more, sometimes I'm not satisfied of myself and keep pouring in..
An ESDS is essentially a sequential dataset where new records are always inserted at the end. You cannot access records directly with a key. However, you may access specific records with a relative byte address (RBA), if you have or can calculate it. In fact, it's fairly common to see CICS application use an ESDS as a log file to write records in sequential order while retrieving the new record's RBA from the RIDFLD operand of the EXEC CICS WRITE command. If the application squirrels away the RBA it can later retrieve the log record directly. Also note that you cannot physically delete a record from an ESDS. Instead, most applications utilize a "logical delete" scheme where a field in the ESDS record is set to a value indicating the record is no longer valid. |
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enrico-sorichetti
Global Moderator
Joined: 14 Mar 2007 Posts: 1845 Location: italy
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/ generic invitation on
please please review your vsam
From the manual
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RELATE(entryname)
names the alternate index's base cluster. The base cluster is an entry-sequenced cluster or a key-sequenced cluster to which the alternate index is to be related. You cannot relate an alternate index to a reusable cluster, to a relative record cluster, or to a VVDS (data set name 'SYS1.VVDS.Vvolser'). An SMS-managed alternate index has the same management class and storage class as its base cluster. |
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the_gautam
Active User
Joined: 05 Jun 2005 Posts: 100 Location: Bangalore
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here is a sample JCL to create the altenate Index on an ESDS.
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//STEP1 EXEC PGM=IDCAMS
//SYSPRINT DD SYSOUT=*
//SYSIN DD *
DEFINE AIX(NAME(A.B.C.AIX)-
RELATE(A.B.C)-
VOLUMES()-
TRK()-
KEYS()-
RECORDSIZE()-
FREESPACE()-
CISZ()-
UNIQUEKEY-
UPGRADE)
/*
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dbzTHEdinosauer
Senior Member
Joined: 20 Oct 2006 Posts: 903 Location: germany
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| that is what I like about this forum: reality or truth does not matter; each will continue to prattle-on showing how much he/she knows, when in reality, few can read, much less give a good answer. |
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Anuj D.
Senior Member
Joined: 22 Apr 2006 Posts: 1124 Location: Mumbai, India
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Hi,
Not sure if I'm also a victim here in this thread, if any how yes, please put your comments in, so that I can learn something new. |
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dbzTHEdinosauer
Senior Member
Joined: 20 Oct 2006 Posts: 903 Location: germany
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Anuj D.,
The only Victims in this thread are those (like yourself) who continue to post meaningful and correct information.
It has only been stated 3 times (by different individuals) that an ESDS dataset does not have 'ALTERNATE' nor 'PRIMARY' index. But, others continue to post 'JCL' to create that which is not 'creatable'.
But that is why these threads are so long. Few people bother to read, they are too busy posting. |
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vch
New User
Joined: 01 Feb 2008 Posts: 16 Location: chennai
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Thanks alot for all your responses..
I created an alternate index to an ESDS file successfully.
so it is confirmed that we can create an ESDS to an ESDS file. |
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