Re: Oracle Table Space Allocation

From: Dave Hau <davehau-no-spam-123_at_no-spam.netscape.net>
Date: Sat, 3 May 2003 08:06:36 -0700
Message-ID: <b90kok$ihe$1@slb6.atl.mindspring.net>

"Guy Honore" <guyh_at_attbi.com> wrote in message news:f9bc6138.0305030617.293f2d8f_at_posting.google.com...
> I was wondering how Oracle allocates space for a new row INSERT: does
> it require that all the space exist in the current block or extent for
> the row, or does it span the row across a second block/extent? Any
> help on the physical layout concepts involved would be greatly
> appreciated.

The new row is stored in a single data block if it fits. Otherwise, it is split up into multiple row pieces to be stored in different data blocks (can be across extents). Oracle calls this "row chaining". A row that contains more than 255 columns is also likely to be split up into multiple row pieces even within a single block, known as "intra-block chaining". Here's a good read:

http://download-west.oracle.com/docs/cd/B10501_01/server.920/a96524/c11schem.htm#2747

Cheers,
Dave Received on Sat May 03 2003 - 10:06:36 CDT