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  1. #1
    Join Date
    Sep 2004
    Posts
    16

    Unanswered: About the Execution plan in Query Processing

    hi,

    When I was trying to understand the stages in Query Processing, I was not able to understand the Execution Plan concept that comes in the PARSE phase.

    Can anybody explain me what exact findings are listed in the Execution Plan during the Parse phase by the Server process.

    Also I am not clear how this Execution Plan is used in the next stage, "ExECUTION PHASE" of the Query Processing.

    help in this regard is greatly useful to me in understanding the concepts.

    Thanks in advance
    sudhav17

  2. #2
    Join Date
    Jul 2003
    Posts
    2,296
    Buy any of Tom Kite's books (or buy both!).
    Expert One-on-One or Effective Oracle by Design

    He explains these concepts in great (but easy to understand) detail
    and includes examples.

    You can also try his website and search under Explain Plan
    http://asktom.oracle.com
    - The_Duck
    you can lead someone to something but they will never learn anything ...

  3. #3
    Join Date
    Nov 2002
    Location
    Desk, slightly south of keyboard
    Posts
    697
    Hi,

    http://www.billmagee.co.uk/oracle/sqltune/index.html "explains!" the principle.

    Hth
    Bill
    Please don't email me directly with questions. I've probably just got home from the pub and cannot guarantee the sanity of my answers. In fact, I can't believe I actually made it home.

  4. #4
    Join Date
    Oct 2003
    Posts
    706
    An SQL query is a non-procedural statement of the problem. It only describes what results you want, not how to get them.

    Before the DBMS can actually do the work, it must evaluate your query, and the present state of the database, to determine exactly what to do. The result of this step is the "execution plan." This actually determines what the DBMS will physically do to carry-out this query. In the so-called "execution phase" it proceeds to do just that.
    ChimneySweep(R): fast, automatic
    table repair at a click of the
    mouse! http://www.sundialservices.com

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