Results 1 to 3 of 3
  1. #1
    Join Date
    Sep 2003

    Unanswered: How to read UNCOMMITED data in Oracle?


    I have these 2 problem? Is there a way in Oracle to read UNCOMMITED data. i.e. in Oracle the normal behaviour is that a user's updates to a table are visible to other users ONLY when the user commits. But in Informix there is this thing called ISOLATION LEVELS. For example by setting the ISOLATION LEVEL to DIRTY READ, a user will read dirty data, i.e. the last uncommited updated value of a field by some other user. Is this possible in Oracle by setting some parameter, say in the INIT file?

    Also WHAT IS THE DEFAULT LOCKING BEHAVIOUR IN ORACLE? I mean if I want Oracle to automatically issue a READ LOCK (so that nobody can update a record, but view only) everytime a table (or row) is read, and for this to be made effective for the ENTIER DATABASE, how can we achive this? Is there a parameter to change in some INIT file???

    Thanks & Regards,

  2. #2
    Join Date
    Mar 2002
    Reading, UK
    Why do you need to read uncommitted data, I dont think you can do this in Oracle.

    And if you want to lock on a read you usually use select ... for update which will lock the relevant records. To do this database wide though would cause locking issues. I would suggest you rework your app to work the way Oracle works (which is much better than most other socalled enterprise databases). In Oracle only writers block other writers, writers dont block readers and vice versa. See this article for more info and get the book if you can.

    there are more parts to this article so do a search on the site

  3. #3
    Join Date
    Jan 2003
    Vienna, Austria

    Re: How to read UNCOMMITED data in Oracle?

    afaik Oracle does NOT support any kind of 'dirty read'

    for different locking strategies please check the Oracle concepts Guide for 'Isolation Levels'

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts