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What is the internal representation of index

 
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yerra

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Joined: 24 May 2005
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PostPosted: Tue Jun 21, 2005 4:39 pm    Post subject: What is the internal representation of index
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When we use index in table , What is the datatype of the index(internal represenation) and what is the max length of the field
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mmwife

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Joined: 30 May 2003
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PostPosted: Wed Jun 22, 2005 5:50 am    Post subject:
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An index contains the offset in bytes from thhe beginning of the tbl to the beginning of the tbl elemmennt referenced. It's represented as a binary value. Not sure about the max size but I'd say it's sufficient to reference data in the largest table permissible (16,777,215 bytes).

Check out the link below:

http://publibz.boulder.ibm.com/cgi-bin/bookmgr_OS390/BOOKS/IGY3LR10/APPENDIX1.2?DT=20020920180651
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ravindra mudumby

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PostPosted: Sun Jul 03, 2005 4:48 pm    Post subject: ravindra --my explanation of internal representation
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When records are manipulated by the system, they're represented in a tree-structure, with data elements at the leaf nodes, and tags or variant components at the non-leaf nodes. The root-node identifies the schema that lends context to the tagging and structuring of the record. Imagine a simple record, consisting of a 'title' element and an 'author' element:

ROOT
TITLE "Zen and the Art of Motorcycle Maintenance"
AUTHOR "Robert Pirsig"


A slightly more complex record would have the author element consist of two elements, a surname and a first name:

ROOT
TITLE "Zen and the Art of Motorcycle Maintenance"
AUTHOR
FIRST-NAME "Robert"
SURNAME "Pirsig"


The root of the record will refer to the record schema that describes the structuring of this particular record. The schema defines the element tags (TITLE, FIRST-NAME, etc.) that may occur in the record, as well as the structuring (SURNAME should appear below AUTHOR, etc.). In addition, the schema establishes element set names that are used by the client to request a subset of the elements of a given record. The schema may also establish rules for converting the record to a different schema, by stating, for each element, a mapping to a different tag path.
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