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

    oracle sql query works

    836150
      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
          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)
            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
              Pavan Kumar
              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
                Thanks Rafi, this type of answer only i was expecting.
                thanks once again.

                Regards,
                Venkat
                • 5. Re: oracle sql query works
                  836150
                  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)
                    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/