Defining System Owned indexes with Offsets

Discussion created by ca.portal.admin on Sep 27, 2006
Latest reply on Sep 27, 2006 by ca.portal.admin
Hello Group,
Can anyone shed any insight on the pros and cons of using OFFSETS on the
WITHIN AREA clause while defining indexes. If defining several indexes
within a single area, Is it best to partition the indexes off based on
page range or percentages or could I just not use offsets and let the
indexes battle it out as to where they are within the area.

IDMS Public Discussion Forum


Re: Defining System Owned indexes with Offsets
"Hello Tim:

I agree with Kay 100%. I don't recommend that you put more than one index
into an area because there are to many issues to deal with.

For example, if you put multiple index sets into one area with offsets, what
happens if one of the indexes needs more space? You can do a number of
things such as changing the offsets or running an expand page. But, in this
example you only need to increase the space for one index and now you have to
expand the entire area. If you change the offsets of one index what will the
effect be on the other index sets in the area? A new analysis of all the index
sets would be required.

By isolating one index to one area you can deal with any issues a lot

You might consider putting multiple files in the area and isolating each
index to a specific file, but there are gotcha's with that technique as well.

My rule of thumb is one to one mapping when it comes to index sets.

Bill Allen

In a message dated 9/27/2006 12:52:25 P.M. Eastern Daylight Time,

If you are concerned about performance, each index should be isolated.
We put every index in its own area at our shop. This has the added
benefit of allowing you to use index-tuning features such as
displacements and page reserves. =20