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  1. #1
    Join Date
    Dec 2002

    Unanswered: Serialization level

    Hi all,

    I want to know what's the correct command that I can use inside a SQL Statement that provides me to read uncommited transactions belonging to other users?
    For instance, I submit this select:
    Select * from employees;
    What can I do in the sql statement above to read also all the records in the employees table that were not commited by other users...
    I hope somebody will answer me,

  2. #2
    Join Date
    Oct 2003
    Oracle does not allow dirty reads, and hence does not even support the read uncommitted isolation level

    To Oracle, dirty reads are EVIL (and I do agree). You might want to have a look at the following site and search for "dirty read"

    Read committed
    This is the default transaction isolation level. Each query executed by a transaction sees only data that was committed before the query (not the transaction) began. An Oracle query never reads dirty (uncommitted) data.

  3. #3
    Join Date
    Sep 2003
    Virginia, USA
    I agree and would like to add that serialization determines the point in time from which you can see committed data. Either you can see new commits during your query, or you only data that was committed prior to your query. There is no way to see uncommitted data.

    When a user updates a row, an flag is set on that row which tells all other users to use data stored in the rollback/undo segment. You cannot unset that flag, and so you have no way to see the uncommitted data.

    Oracle9i OCP

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