Re: row migaration

Mark D Powell wrote:
> No, row migration is where on update the new row size exceeds the space
> available to store the row in the block so Oracle migrates the row to a
> new datablock. The rowid remains the same as Oracle keeps a pointer to
> the new physical row piece location at the original location. This
> means an extra IO is required to fetch the row when the fetch is via
> randon IO since the indexes point to this original slot. When the
> fetches are done via a full table scan Oracle does not bother to fetch
> the row till it hits the physical block that holds the row.
Mark,

When are the tumbstones/forward pointers cleaned up? I recall a lot of debate recently about how Oracle doesn't need reorg. In DB2 excessive row-migration is fought with reorg....

Cheers
Serge

-- 
Serge Rielau
DB2 Solutions Development
DB2 UDB for Linux, Unix, Windows
IBM Toronto Lab