For a dimension to be recognized as a time dimension, you need to select the Time Dimension check box in the Dimension dialog box and at least one level of a time dimension must have a chronological key
for more information refer this
Time dimension is created where you need to have time series calculations like the AGO, TODATE and new 11g feature PERIODROLLING.
Creating a time dimension is initially the same as creating a regular dimension, except on the dimension properties dialog you tick the “Time dimension” tickbox.
Please refer the below for good understanding:
Hope this helps to resolve.
Hi, What is the chronological key use?
A. Typically time dimension differs from all other dimensions in one way and that is,
all other dimensions dont care about the order of the values in it.
e.g. 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 dimensiion 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 chronolgocial key?
Analyse it yourself. If you kept year as chro 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 oif the dimension which needs to be the chronological key. In the abouve case it should be date.
You can select either date or date_id(this could be a sequence generator values).
2. what is the use time dimension?
A.If all you want is to achieve drills from Month, Quarter and Year then treat it as a normal dimension and create the levels. But if you want to do calculations like YTD, QTD and MTD then you need to create a time dimension.
Refer the above link for time dimension.
Award points it is useful.
Edited by: Satya Ranki Reddy on May 2, 2012 12:29 AM