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6 Replies Latest reply: Mar 2, 2011 4:27 AM by Rafi (Oracle DBA) RSS

oracle sql query works

836150 Newbie
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Can any body tell , how the sql select statement will works ? how it will come across the 3 phases 1.pharse 2.execute and 3. fetch


what is the parameter in oracle 9i and 10g for compress the dumpfile in export and import?
  • 1. Re: oracle sql query works
    John Stegeman Oracle ACE
    Currently Being Moderated
    A simple search, or even just reading the titles of the first pages of posts would find {thread:id=2184318}, which was asked and answered within the past few hours

    For your second question, all of the fine [url http://www.oracle.com/technetwork/indexes/documentation/index.html]documentation is online. You'll find the import/export information in the Utilities Guide of the DB documentation.
  • 2. Re: oracle sql query works
    Rafi (Oracle DBA) Pro
    Currently Being Moderated
    Hi,
    SQL query executes in 3 phases
    1)Parse
    2)Execute
    3)Fetch

    1)Parse: In this phase the query of user is converted into oracle format,where it performs the syntax check,symantic
    check and than it goes into execution phase.

    2)Execute: In this phase the optimizer help this query for taking execution plan,where the query executes depends
    on statistics collected.

    3)Fetch: In this phase after executing,The user is given the required result.This is also called as display.


    For compress parameter in oracle 9i and 10g check the below link:

    http://aprakash.wordpress.com/2009/11/14/compress/



    Best regards,

    Rafi.
    http://rafioracledba.blogspot.com/
  • 3. Re: oracle sql query works
    PavanKumar Guru
    Currently Being Moderated
    Hi,

    Welcome to forums.. !!
    Can any body tell , how the sql select statement will works ? how it will come across the 3 phases 1.pharse 2.execute and 3. fetch 
    Try to refer to : How the select Query Works
    Oracle documentation explains every thing, just spend some time.
    what is the parameter in oracle 9i and 10g for compress the dumpfile in export and import?
    You must check the Oracle documentation. From high level the compress parameter works different for both versions while allocations the extents.

    - Pavan Kumar N
  • 4. Re: oracle sql query works
    836150 Newbie
    Currently Being Moderated
    Thanks Rafi, this type of answer only i was expecting.
    thanks once again.

    Regards,
    Venkat
  • 5. Re: oracle sql query works
    836150 Newbie
    Currently Being Moderated
    Rafi,

    in these 3 phases what is the role of shared pool,data dictonray cache and library cache and DB CACHE. what exactly server process will do?

    Thanks
    Venkat
  • 6. Re: oracle sql query works
    Rafi (Oracle DBA) Pro
    Currently Being Moderated
    Hi Venkat,
    in these 3 phases what is the role of shared pool,data dictonray cache and library cache and DB CACHE. what exactly server process will do?

    Ans: Shared pool consists of Library cache and data dictionary cache

    1)Library cache: Library cache is a place where your sql and pl/sql statements are executed.

    2)Data dictionary cache: In this place user validation take places.

    DB cache: Database buffer cache is a place where server process bring back data from datafiles (physical portion)

    Note: DBWR writes data from database buffer cache to datafile server process do the reverse work.

    Hope it helps....Please mark the answer which help you so that other person can get to it easily.




    Best regards,

    Rafi.
    http://rafioracledba.blogspot.com/

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