Row chaining
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Thread: Row chaining

  1. #1
    Join Date
    Feb 2006
    Posts
    162

    Row chaining

    Hi,

    Please anyone explain me,what is row chaining & row migration?

    Thanks,
    Malru

  2. #2
    Join Date
    Mar 2006
    Posts
    40
    When a row is initially inserted into a table and the row is too large to fir in one data block, the row is "chained" in multiple blocks.
    When a row is already inserted in the bklock in it fits in it, but later it is updated and becomes bigger and does not fit any more in the block - the entire block is "migradted" to another block. The initial block contains a link to the migrated block so the initial rowid is not changed.
    Both of these occurences decrease I/O performance when reading these blocks.
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  3. #3
    Join Date
    Nov 2000
    Location
    London
    Posts
    94
    Seems to me that you've posted a lot of threads in a short space of time asking questions, mostly about fairly basic DBA tasks. Have you tried searching the web first?

  4. #4
    Join Date
    Sep 2002
    Location
    England
    Posts
    7,331
    rhetorical question if ever I saw one there

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