'Changing Dimension' option??

From: Graeme Scott [MSFT] (graemes_at_online.microsoft.com)
Date: 04/26/04 

Date: Mon, 26 Apr 2004 07:47:20 -0700

Hi,

Dimensions that are defined as "Changing" dimensions are
optimised to support dimension structure change. A
common scenario is for a dimension member to change from
having one parent member to have another existing parent
member.

For scenarios where you only add dimension members to an
existing dimension structure, the dimension does not have
to be defined as "Changing". This dimension modification
can be accommodated by performing an increment update.

When deleting dimension members from a dimension the
dimension will have to be fully reprocessed. Any cubes
using this dimension will also have to be reprocessed.

In your scenario the decision to define a dimension as
a "Changing" dimension depends on the type of dimension
update and if you with to avoid fully reprocessing the
dimension and the cubes that use the dimension.

Using "Changing" dimensions has an impact on the initial
aggregations available within cubes after the cubes have
been processed.

For more information the following white paper contains
useful information about changing dimensions:

http://www.microsoft.com/technet/treeview/default.asp?
url=/technet/prodtechnol/sql/maintain/Optimize/AnSvcsPG.as
p

Graeme Scott [MS]

This posting is provided "AS IS" with no warranties, and
confers no rights.

>-----Original Message-----
>Hi,
>
>Can someone please help me understand what the 'Changing
Dimension'
>option is? (we come across this under the advanced
options on one of the
>dimension wizard' screens)
>
>The description says "..this options allows to add,
remove, and move
>move dimension members without having to re-process the
cube". I hope
>you will not bawl out at me for not understanding the
obvious or going
>through the BOL first. I did, but sometimes find it
difficult to apply
>the description in BOL... so my apologies in advance ;)
>
>In my scenario 4 out of 6 dimensions updated daily (i.e.
the underlying
>tables on which these 4 dimensions are based are updated
daily using
>ETL). So given this scenario, my questions are:
>
>1) Should I use the 'Changing Dimension' options for
these 4 dimensions
>
>2) What advantages will I get (I hope there are more
than just the
>description which I copy/pasted above)
>
>3) Will I still have to process the cube if the
remaining 2 dimensions
>which it uses are shared (not private) but are not
changed that
>frequently i.e. maybe once every 15-20 days
>
>Many TIA for helping me understand.
>
>.
>

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