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Thread: Explain

  1. #1
    Join Date
    Feb 2005
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    Unanswered: Explain

    I need a manual about EXPLAIN/SQL

  2. #2
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    May 2003
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    First try the Must Read Before Posting thread. Then move on to the Useful DB2 Stuff thread.
    M. A. Feldman
    IBM Certified DBA on DB2 for Linux, UNIX, and Windows
    IBM Certified DBA on DB2 for z/OS and OS/390

  3. #3
    Join Date
    Feb 2005
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    118

    create access plan

    The CREATE ACCESS PLAN from the command center (in db2 ver7.2 for windows) creates a visual display of the access path for the SQL in the script. The visual display can be seen by clicking on the ACCESS PLAN tab on the command center.
    Is it this facility that is called the visual explain or is it something that needs to installed seperately ?

    Anil

  4. #4
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    The EXPLAIN functionality depends on which operating system DB2 is running on (OS/390, UNIX etc.), but it comes with DB2 and does not have to be installed separately. However, in some cases it may be necessary to run some IBM supplied DDL to create the DB2 tables used for EXPLAIN.
    M. A. Feldman
    IBM Certified DBA on DB2 for Linux, UNIX, and Windows
    IBM Certified DBA on DB2 for z/OS and OS/390

  5. #5
    Join Date
    Feb 2005
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    118
    I am using a DB2 UDB ver 7.2 client on Windows 2000. How would I invoke the tool VISUAL EXPLAIN ?
    Now if I go the command center, there are four tabs 'Interactive, Script, Query Results, and Access Plan'. Now depending on which tab you click, the menu bar options change. for 'interactiev', and 'script' tabs, there is also a corresponding option in the menu bar. If you click on the menu bar option (say for tab 'script', menu bar option 'script'), there is an option CREATE ACCESS PLAN.
    Then after executing the script click on the tab 'Access Plan', and this time you can use the different access plan menu options to view the explained SQL.
    So my question is, is it this feature that is called VISUAL EXPLAIN, or is it a different option like CLP, CCA, CC etc

    thanks.
    Anil

  6. #6
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    There is a batch explain program called db2expln and the related explain table format tool called db2exfmt. See the Command Reference.

    I don't recall if V7 has visual explain (V7 is no longer supported by IBM) but if it did exist, it was an option in the Control Center (maybe right click option?). I don't have a V7 client to check, so I don't recall.

    You could try searching the Master Index manual for Version 7.
    M. A. Feldman
    IBM Certified DBA on DB2 for Linux, UNIX, and Windows
    IBM Certified DBA on DB2 for z/OS and OS/390

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