Note 1: OBIEE offers two calculation types for measure in the repository:
logical
physical
You can define calculations in either of the following ways:
* Before the aggregation, in the logical table source.
* After the aggregation, in a logical column derived from two other logical columns. For example: sum(col A)
* sum(col B)
Note 2: A measure column is a column unlike the baseline column that has a default aggregation rule defined in the Aggregation tab of the Logical Column dialog in the repository.
Measure columns always calculate the aggregation with which they are defined.
Measures need to be defined in a logical fact. Any column with an aggregation rule is a measure.

Query Limits. You can limit queries by the number of rows received, by maximum run time, and by restricting to particular time periods. You can also allow or disallow direct database requests or the Populate privilege.
See figure below.

Object-level security controls the visibility to business logical objects based on a user's role. You can set up object-level security for metadata repository objects, such as subject areas and presentation folders, and for Web objects, such as dashboards and dashboard pages, which are defined in the Presentation Catalog.
1) Business logic object
This controls access to objects, such as:
* subject areas
* presentation tables
* presentation columns
For example, users in a particular department can view only the subject areas that belong to their department.
2) Web object security
This provides security for objects stored in the Web Catalog, such as dashboards, dashboard pages, folders, and reports. You can view only the objects for which you are authorized. For example, a mid-level manager may not be granted access to a dashboard containing summary information for an entire department.

Example (see step 4 and 5 below): Getting Top-N Sales Reps for Year and Year-1
1. Under the "Business Model and Mapping" Layer, right click the "F1 Revenue" and select "New Object" ->
"Logical Column..."
2. In the "Logical Column" Window give for Name: Year Ago Revenue as seen below:

3. Goto the "Column Source" Tab and select "Derived from existing columns using an expression" radio button then click on the "Edit Expression" icon.
4. Enter the following expression in the "Expression Builder" Window by selecting "Functions" in the
"Category:" list, "Time Series Functions" in the "Functions:" list then "Ago" "Time Series Functions:" section.
5. Select the "<<Measure>>" in the "Ago( )" function, then select "Logical Tables" in the "Category:" list,
"F1 Revenue" in the "Logical Tables:" list, then double click the "Revenue" in the "Columns:" list.
Etc.

Creating Logical Time Dimensions
Compared to modeling an ordinary dimension, the time dimension requires just two additional steps: selecting the Time option in the Logical Dimension dialog, and designating a chronological key for every level of every dimension hierarchy.
Note: Time dimensions and chronological keys. You can identify a dimension as a time dimension. At least one level of a time dimension must have a chronological key. The following is a list of some guidelines you should use when setting up and using time dimensions:
* At least one level of a time dimension must have a chronological key.
* All time series measures using the AGO, TODATE, and PERIODROLLING functions must be on time levels. AGO, TODATE, and PERIODROLLING aggregates are created as derived logical columns.