How to populate the time component of a cube?

Question

We have a question regarding how to populate the time component of a cube. Let me explain:
We are using OWB 10gR2. We have created a cube with several dimensions. We are now building the mapping to load the cube. The cube operator has two columns for every dimension (e.g., "customer" and "customer_id" for the "customer" dimension).
We understand that, in this case, "customer_id" stands for the dimension business key, so we create an arrow from the business key in the source table to the "customer_id" column in the cube operator.
So far so good. The mapping works all right, and the cube is loaded correctly.
Now we need to do the same for the time dimension. We have already created the time dimension and we have loaded it. We have also included it in the cube, so now we have two new columns in it: "time_day_code" and "time", both NUMBER data type.
We have the "sale_date" column (DATE data type), in the source system and, of course, now we want to populate the date column in the cube. We suppose that, somehow, we have to translate the "sale_date" field into the numeric column of the surrogate key of the time dimension. How should do we do this? I suppose that OWB must do the translation for us, just as it does for the other dimensions, but how? We have been looking into the manuals, and we have found no explanation on how to go about this.
Any help would be appreciated.
Best regards
Juan Algaba

Answer 1

Hi Juan
You are right this should have been in the manuals, checked and there is only a brief mention (Using a Time Dimension in a Cube Mapping section)
The identifier format should have been documented for each level and will involve creating the formatted attribute for input to the cube operator's time dimension reference attribute.
The time dimension business keys are stored as follows;
Day Level - YYYYMMDD
Month Level - YYYYMM
Week Level - YYYYWW
Quarter - YYYYQ
Year - YYYY
If you have a source that has a SQL date datatype for example and want to construct the key for a cube's time dimension at the day level something like the following expression can be used to construct the time reference from a SQL date...
to_number(to_char( time_key, 'YYYYMMDD'))
The result of this expression can be used as input to the cube's time dimension attribute.
Cheers
David