How to improve Discoverer performance by using summary folders How to improve query performance by optimizing the SQL that Discoverer generates

10-4 Oracle Fusion Middleware Configuration Guide for Oracle Business Intelligence Discoverer Note : After editing the pref.txt file, you must run the applypreferences script to apply the preference changes you have made for more information, see Section 9.4, How to set default user preferences for all users . Then stop and restart the Oracle BI Discoverer Service for more information, see Section 4.3, How to start, stop, and restart the Discoverer preferences server component using opmnctl . If the value of ObjectAlwaysAccessible is not 0, Discoverer does not perform the security check when the query is built and assumes that the tables are accessible. Note : Database security is always respected. The security check is made when the query runs, instead of when the query is built. As a result, Discoverer displays the list of folders more quickly. Disabling the security check is likely to be more appropriate on systems where users’ access rights change relatively infrequently. Note : If a user selects a folder based on a table to which they do not have database access, Discoverer ensures database security when the query runs and no rows are returned.

10.3.3 How to improve Discoverer performance by using summary folders

When used correctly, Discoverer summary folders significantly improve query response times. For example, queries that use summary folders might take only seconds to run, whereas queries that return the same result set but do not use summary folders might take several hours. Summary folder management is the key to good performance with Discoverer implementations. Summary folders can be based on materialized views or summary tables, with the following differences in behavior: ■ if a Discoverer query includes a summary folder that is based on a materialized view, the database automatically rewrites the query to use the materialized view ■ if a Discoverer query includes a summary folder that is based on a summary table, Discoverer automatically rewrites the query to use the summary table providing the summary table has been registered with the EUL Use the SQL Inspector dialog to view the path taken by the query, and to find out whether the database has rewritten the query. For more information about how Discoverer manages summary folders, see Oracle Fusion Middleware Administrators Guide for Oracle Business Intelligence Discoverer.

10.3.4 How to improve query performance by optimizing the SQL that Discoverer generates

To improve query performance Discoverer optimizes the SQL that it generates, in the following three areas: ■ item trimming Discoverer removes references to irrelevant or unused columns and expressions in the query SQL, improving performance. To enable item trimming, set the value of the user preference SQLItemTrim to 1. ■ join trimming Discoverer detects and eliminates joins where possible from queries without affecting the result set, which improves query performance. To enable join trimming, set the value of the user preference SQLJoinTrim to 1. Optimizing Oracle BI Discoverer Performance and Scalability 10-5 ■ flattening Discoverer minimizes the use of inline views in the query SQL, which makes it easier for the database to efficiently parse the SQL and select an optimal execution path. To enable flattening, set the value of the user preference SQLFlatten to 1. For more information about: ■ the user preferences SQLItemTrim, SQLJoinTrim, SQLFlatten, see Section 9.6, List of Discoverer user preferences ■ the join properties to choose to improve performance, see the Oracle Fusion Middleware Administrators Guide for Oracle Business Intelligence Discoverer

10.3.5 How to improve Discoverer performance by using Discoverer Administrator hints