"News" <news_connection_at_yahoo.fr> wrote in message
news:dit8d1$c20$1_at_apollon.grec.isp.9tel.net...
> "DA Morgan" <damorgan_at_psoug.org> wrote in message
> news:1129418200.7123_at_yasure...
> could you tell me if each block in Oracle points to the next and previous
> blocks ?
Ok there's no such thing because blocks are contiguous within extent. So for
table scan without index, Oracle reads the content of extents within
segments in the order in which they are declared in the header of the
segment ? and within the extent it reads adjacent data blocks as a whole.
Extents are not contiguous so the order in which it reads extents varies
since allocation deallocation of extents may happen meanwhile when
inserts/deletes occur.
So I think the right answer is not from top to bottom or bottom to top but
arbitrary?
Received on Sun Oct 16 2005 - 05:54:46 CDT
