Data source connections

The data source connection specifies the parameters needed to connect to the database, such as the location of the database and the timeout duration. A connection can include credential information and signons.

For more information about data source connections, see the IBM Cognos Analytics Administration and Security Guide. For information about the parameters to connect to your specific data source, see the vendor documentation.

Multiple data source connections

Each data source can have one or more physical connections to the database.

If you have access to more than one data source connection in a data source, you are prompted to select a data source connection when you open an IBM® Cognos® Framework Manager project. You can use multiple data source connections in a single data source to facilitate the migration from one environment to another and maintain the integrity of a project.

For example, you can use multiple data source connections to work with metadata from a test data source. Create a new project, using the GoSales data source connection. Create and modify the objects you want in the project, and test to ensure that the project is modeled the way you want. After you close the session, and reopen the Framework Manager project, you can select the production data source connection. When you publish the package to the IBM Cognos Analytics server, your users choose which data source connection they want to use in their report.

Multiple connections to the same data source must be defined in IBM Cognos Administration. If you want to support multiple connections for each data source, clear the data source catalog and schema names, and create a connection for each database in IBM Cognos Administration.

Tip: If you are working with multiple cubes containing unlike metadata, use separate data sources for each cube. To be able to expand an OLAP package in the Studios, the internal name of both cubes must be the same. If you want to run saved reports that use different data source connections, the cube name, as well as the dimension, hierarchy, level and attribute names, must be the same in both cubes. If you use a single data source with a separate connection for each cube, the internal names of all the cubes must be the same.

Isolation levels

The isolation level specifies how transactions that modify the database are handled. By default, the default object gateway is used. Not all types of databases support each isolation level. Some database vendors use different names for the isolation levels.

Queries that are executed by reports and analysis are intended to be read-only operations. The queries execute with a unit of work at the data source known as a transaction with either a default or administrator-defined isolation level. Report authors should not assume that queries that execute stored procedures commit any data written by the procedure. In some environments, changes made by a procedure may be committed due to features of the database. A stored procedure that is marked for-write in Framework Manager commits changes but can only be used by Event Studio.

If you need specific queries to run with different isolation levels, you must define different database connections.

For OLAP data sources, including SAP BW, the transaction unit of work is read-only.

The following sections list the isolation levels in increasing order of isolation. Each section contains a description of the isolation level and information about equivalent isolation levels in different databases.