Report Runs Slowly
The following list of questions can help you troubleshoot a slow report:
- Has the report always been slow, or did it recently become slow?
If it recently became slow, can you identify an event that occurred before the change? Events could include changes to configuration settings, an introduction of firewalls or proxies, changes to existing firewalls or proxies, changes to virus scans on temp directories. - Is the performance slow for all reports or just for one report?
If all reports are slow, the issue may be due to the PPM environment or database. If just one report is slow, the issue may be specific to a report element. - How many queries does your report contain?
The number of queries on the report will proportionally affect the report execution time. - Does the report run slowly for everyone, or for just one user?
If the report runs slowly for just one user, the issue may be due to something in the user's environment, such as virus scanning, page file size or location settings, or their location on the network. - Do your queries require local processing?
The following report elements require local processing: crosstabs and charts, master relationships, unions or joins, multiple fact queries. Local processing requires the Cognos server to compute operations on the result set returned by the database, which can impact the execution time.
Tips to improve report performance:
- Change the order in which items are queried from the database. For more information, see Working with Queries
- Share queries between lists and repeaters.
You can share an identical query between data containers that use it. To share a query, data containers must be lists, repeaters or repeater tables and must use the same grouping structure and list of properties. The data containers cannot be part of a master detail relationship. Sharing queries improves performance by minimizing the number of queries executed against the database.
To share a query, set the Share Result Set property for the data container to Yes. - Use Select & Search prompts instead of value prompts if your list of prompts is long. For more information, see Building Your Own Prompt and Prompt Page.
- Provide your own prompt values in a prompt to avoid accessing the database. For more information, see Specifying Prompt Values.
- Suppress null cells using filters. For more information, see Suppressing Null Cells Using Filters.
- Set page breaks without creating master detail relationships. For more information, see Creating a Page Break or Page Set.
- Do not put filters on non-identifiers.
- Avoid combining large hierarchy levels and sets in a drill-through report in a way that creates large queries.
- Use database functions when possible. See Using the Expression Editor.
- Use fixed width objects in PDF reports by setting their Size & Overflow properties. See Set List Properties, Formatting Crosstab Reports, Customizing Chart Properties and Setting Map Properties.
Overflow Error Occurs When a Value in a Crosstab is More than 19 Characters
In a crosstab report, values support a maximum of 19 characters, including the decimal point. If a value exceeds 19 digits, an overflow error occurs. By default, the decimal precision is set to 7 digits, which restricts the number of integers to 11 digits.
Note: The default is controlled by the Cognos configuration and is not user-configurable.
A Report Does not Run Because of Missing Items
You attempt to run a report and a message indicates that one or more items are missing or changed. Each missing item is listed by its MUN (member unique name). The MUN includes the complete path within the hierarchy for the item. When you place your cursor on an item in the Source tab, the MUN for that item is displayed in a tooltip.
The solution is to update your report to exclude items that may no longer be available (a custom field that was deleted, for example).
Drill-through links are Not Active in Safari
When viewing a PDF report in the Macintosh Safari browser, you cannot open hyperlinks. This is because Safari does not have the necessary Adobe Acrobat plug-in
To avoid this problem, use HTML format when creating drill-through reports that may be viewed in Safari.
Unable to View Active Reports in Mozilla Firefox
When you try to view an active report in the Mozilla Firefox browser, you may see a blank page or a message such as the one below appears.
Your report is ready and will download to your Web browser in a few moments.
However, the report never appears. This problem occurs when you try to run an active report from within Report Studio.
The issue is with the UnMHT add-on, and was reported on the UnMHT Warehouse Web site.
To work around the issue, in Report Studio use Download Active Report when clicking the Run button. If you select Run Active Report, the report will not render.