DBAsupport.com Forums - Powered by vBulletin
Results 1 to 4 of 4
  1. #1
    Join Date
    Dec 2005

    Need for the Extent storage structure


    I am trying hard to understand the Oracle database architecture. It is mainly due to my lack of knowledge, I suppose, that I cannot seem to understand the need for the Extent logical storage structure. Is it cumbersome to talk directly in terms of data blocks? Does dealing with extents vs dealing with data blocks directly reduce the storage management overhead for Oracle? What is the rationale behind having this intermediate storage structure between the segment and the data block? Please clarify.


  2. #2
    Join Date
    Apr 2001
    Bangalore, India
    Thomas Saviour(royxavier@yahoo.com)
    Technical Lead (Databases)
    Thomson Reuters (Markets)


  3. #3
    Join Date
    Aug 2002
    Colorado Springs
    It allows for growth of the segment in stages, where each stage is a contiguous set of blocks for that segment. The alternative would be to have individual blocks scattered around, which would be very inefficient to read with a full table scan and require another large structure to tell oracle where each one is.
    David Aldridge,
    "The Oracle Sponge"

    Senior Manager, Business Intelligence Development
    XM Satellite Radio
    Washington, DC

    Oracle ACE

  4. #4
    Join Date
    Dec 2002
    Bangalore ( India )
    Dave.. but do we know if the extents will be contigious for sure with RAID?.. if not we still have issues with FTS.. dont we?

    Extents is a logical structure which will want the blocks in it to be contigious but cannot be assured how OS allocates in disk..

    The rationale behind extent is to simplify the understanding of allocation process in a datafile/s.. and ofcourse it will be contigious most of the times and hence making the FTS process efficient.


    "I Dont Want To Follow A Path, I would Rather Go Where There Is No Path And Leave A Trail."

    "Ego is the worst thing many have, try to overcome it & you will be the best, if not good, person on this earth"

Posting Permissions

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

Click Here to Expand Forum to Full Width

We have made updates to our Privacy Policy to reflect the implementation of the General Data Protection Regulation.