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Secondary Index concept in IMS DB

 
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srinis
Warnings : 1

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Joined: 04 Jun 2007
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PostPosted: Fri Jun 29, 2007 4:29 pm    Post subject: Secondary Index concept in IMS DB
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Hi,

i am not working on Ims db, but i know. i want a little bit explanation of Secondary Index concept.

Regards,
sree.
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dick scherrer

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Joined: 23 Nov 2006
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PostPosted: Fri Jun 29, 2007 7:22 pm    Post subject:
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Hello,

A secondary index in IMS (as well as vsam, db2, and any other database) provides additonal direct access to rows.

For example an "employee" table might have a primary key of "employee_id". Each employee also has their current department code in their employee table entry. If dept_no was a secondary index, a query could directly retrieve all of the people in a specific department without traversing the entire table.
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Bitneuker

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Joined: 07 Nov 2005
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PostPosted: Fri Jun 29, 2007 9:33 pm    Post subject:
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I wonder why I posted the sticky telling people where to find information about IMS icon_cry.gif Again: following the first link in this sticky and searching for 'SECONDARY INDEX' i.e. leads to this, and there's a lot more to find.
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Devzee

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Joined: 20 Jan 2007
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PostPosted: Sat Jun 30, 2007 10:04 am    Post subject:
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srinis Refer to
Quote:
d.sch.
post which has generic concept of secondary indexing.

Bitneuker Not everyone looks at the sticky or the links. People need direct answers without spending much time in reading the manuals or understanding the full concept.
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Bitneuker

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PostPosted: Sat Jun 30, 2007 11:15 pm    Post subject:
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Quote:
Bitneuker Not everyone looks at the sticky or the links. People need direct answers without spending much time in reading the manuals or understanding the full concept.


Devzee: They should IMHO. The original question posted tells us the guy wants to understand S.I. He didn't post a direct question to solve any problem so in this case I think leading him to the information via links is a good option. Please take my original post as 'non posted'.
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autobox

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PostPosted: Tue Jul 03, 2007 1:44 pm    Post subject:
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Simplly put, Secondary Index is that you can use a key other than the original key of root segment to access a certain segment occurence directly.
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Sandy Zimmer

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PostPosted: Wed Jul 04, 2007 4:56 pm    Post subject:
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Using an IMS utility to build secondary indices as individual databases is fast. You then read the secondary index as a database. Talk to your DBA. I wrote an HR system with 5 secondary indices. It worked great!
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