Chronological Key

Def : Uniquely identify data on each level in Dimensional hierarchy

All other dimensions don’t care about the order of the values in it.

Example : In region_dim the values are north, south, west and east. Here nobody wants to see whether north comes first or south comes first. I.e. no order is required here.

In the case of time dimension there needs to be a particular order for all the values present in it.

e.g. 2010 is earliest and 2004 is older. Dec-10 is earliest and jan-10 is older. I.e. the values in the time dimension needs to follow a particular sorting order. So the chronological key is the key which tells the obiee that the data is incrementing based on the chronological column.

Here you may get another doubt. i.e. you are having columns like year, half_year, quarter, month, week and day. Here which one should become the chronological key?

Analyze it yourself. If you kept year as chronological key then obiee will be confused whether jan-10 is earliest or feb-10 is earliest. Because it knows only that 2010 is earliest and 2009 is older.

So always it should be the lowest level of the dimension which needs to be the chronological key. In the above case it should be date.

You can select either date or date_id(this could be a sequence generator values). 

Thanks and Regards 

Rakesh Patil
rakeshpatil002@gmail.com

OBIEE Foundation Suite 11g Certified Implementation Specialist