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Limited support BMC provides limited support for this version of the product. As a result, BMC no longer accepts comments in this space. If you encounter problems with the product version or the space, contact BMC Support.BMC recommends upgrading to the latest version of the product. To see documentation for that version, see BMC AMI Ops Monitor for Db2 13.1 image-2024-5-19_8-5-1.png .

Main panels

The main panels for the Explain process are as follows:

  • Explain Object Specification allows you to specify criteria to retrieve an object or statement to Explain. Use this panel to:

    • Specify whether to list objects that you can select to Explain
    • Specify to Explain the specified objects in batch
    • Specify whether to provide additional Explain options
    Warning

    Note

    The appearance of this panel varies, depending on the route by which you enter the Explain function. For example, you might be asked to specify a subsystem ID for your Explain.

  • Explain Options is displayed when you select Explain Options on the Explain Object Specification panel or from the OPTIONS task bar. Use the Explain Options panel to specify or change Explain processing options.

    • Explain Object Selection List is displayed when you specify Processing Mode L, List object(s), on the Explain Object Specification panel, or when you execute BMCEX on objects from CATALOG MANAGER. Use the Explain Object Selection List to specify objects for an Explain operation. A task bar and action codes provide more room on this panel for displaying Explain information. You can also use the FIND, RFIND, and ZOOM commands on this panel.

      Because a plan can consist of DBRMs, a package list of collection IDs, or a mixture of both DBRMs and packages, the Object Selection List for plans shows both the DBRMs and package list.

      The appearance of the Explain Object Selection List is controlled by a member in a layout data set.

  • Explain Results displays the results of online Explain operations, including the following information:

    • The estimated cost (in timerons) of executing the SQL statement
    • The predicates used in the SQL statement
    • Whether a mismatch in data type or length might be causing the Db2 optimizer to choose a bad access path
    • Access path information
    • Expert rules regarding the syntax of the statement, the access path, and current statistics on the objects
    • Statistics from the Db2 catalog for tables referenced in the access path steps

    In addition, indexes referenced in the access path steps are displayed and highlighted with the table statistics, followed by indexes that are available but not referenced in the step. You can drill down further to display table and index columns, and their related statistics.

    The information on the Explain Results panel is divided into the following sections:

    • The Statement area is located at the top of the panel, this section shows information such as the type of Explain that was performed, the statement number, the cost in timerons, the statement text, and the cost in service units.

    • The Access path area is located at the bottom of the panel, this section displays information from the Db2 PLAN_TABLE. You can drill down to table and index columns and statistics for each query block.

      A task bar and action codes provide more room on this panel for displaying Explain information. From this panel, you can drill down to get more information, display reports on demand, edit SQL, and perform additional Explains. You can also use the FIND, RFIND, and ZOOM commands on this panel.

      The appearance of the Explain Results panel is controlled by the same layout data set that controls the display of the Explain Object Selection List.

Related topic

Overview-of-the-Explain-function


 

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BMC AMI Ops Monitor for Db2 12.2