Re: Row Migration

On Wed, 18 Jul 2007 16:21:04 -0000, Rahul <rahul.nimmagadda_at_gmail.com> wrote:

>My Query --
>Instead of having a pointer from the original block to the new block,
>why doesn't oracle server delete the information about that particular
>row in the row directory slot of the original block and put the
>information about the row in the row directory slot of the new block
>as it is anyway moving the entire row to a new block. This can
>increase I/O performance as the number of I/Os required are less than
>the previous scenario.

The obvious answer to this one is that in that case Oracle would also have to update all index-entries associated with this record. This will result in yet more I/O and more redo. Also, row migration many times is simply the result of improper design. In that case one better fixes the design compared to implement additional kludges.

-- 

Sybrand Bakker
Senior Oracle DBA