Preparing to work with your external data

To work with your external data, follow the process in this section.

There are four steps to preparing to work with your external data. The following diagram details these steps.

Figure 1. Process to prepare to work with external data
a diagram of the four steps of the process, as described in the next sections
  1. Prepare your external data file for import.

    Ensure that your external data file matches your enterprise data for your reporting needs. For example, if your external data file contains sales values by month, ensure that the formatting of months in your file matches the formatting used in your enterprise data source. Ensure that you can uniquely link at least one column from your external data file, such as product codes or years, with your enterprise data source.

    The maximum file size that you can import is 2.5 MB, with a maximum of 20000 rows. You can import a maximum of one external data file per package. Your IBM® Cognos® modeler can override these governors in IBM Cognos Framework Manager.

  2. Import your external data.

    You import your external data file from your own computer or from a location on your network into an existing IBM Cognos package.

    A step-by-step wizard guides you through importing your data. If you want to create reports that contain data from both your external data file and your enterprise data source, you must link data items from the two data sources. You can import all or a subset of data columns from your external file.

    By adding external data, you extend an existing IBM Cognos package definition with the new data items from your file and you create a new package.

  3. Create reports with your external data file.

    After you import and link your external data, it appears as a new namespace in the data tree of the Source tab source tab and is integrated with the IBM Cognos content.

    You can then create reports with your data and perform any operation, such as filtering, sorting, grouping, or adding calculations. When you run the report, it uses data items from your external data file.

    You can save reports that contain your external data within the My content area of the IBM Cognos Analytics portal.

  4. Determine whether you want to share your reports that use external data with other people in your organization. If you decide to share, take into account these considerations.

Working with Date Data

If the data that you import contains dates, ensure that the dates use the format yyyy-mm-dd.

Working with Dimensional Data Sources

If your enterprise data source is dimensional, such as OLAP or dimensionally-modeled relational, and you want to link your external data with your enterprise data, you must first create a tabular or list report. Create and save a list report with your enterprise data that contains the data items that you want to use to link with your external data. Ensure that you remove the aggregate rows that are automatically added in the footer of the list. This list is a projection of your dimensional data source.

When you import your external data, use the list report that you created to link your external data with the query subject from your enterprise data.

Data in your external file is relational by nature because it consists of tables and rows. If your enterprise data source is dimensional, you can still import and work with your external data. However, you cannot mix relational data from your external data files, and dimensional data from your enterprise data source within the same query. For example, a data container, such as a list, crosstab, or chart, uses one query and you cannot mix relational and dimensional data within the same list, crosstab, or chart. Doing so will cause an error.

If you want to use data from both the external data file and the original package within the same query, you must link the external data to a query subject within the current package instead of another report.

Working with External Data in an Unsecured IBM Cognos Application

If your IBM Cognos application is not secured, and users can log on anonymously, you may encounter issues if multiple people import external data in the same package.

For example, Robert imports his external data into package A and saves the package and reports he created in My content. Then, Valerie also imports her external data into the same package A and saves the package in My content. Valerie has therefore overwritten Robert's external data in package A. Now, if Robert tries to run one of his reports, he encounters errors because his external data is no longer in package A.

To avoid this problem,

  • save packages that contain external data with a unique name.
  • apply security to your IBM Cognos applications so that users do not share the same My content area.