RE: Question about Dual
- From: Connor McDonald <hamcdc@xxxxxxxxxxx>
- To: oracle-l@xxxxxxxxxxxxx
- Date: Sun, 12 Sep 2004 11:19:55 +0100 (BST)
I'd guess its reduction in latching costs. There's no such thing as consistent
read with x$
tables, so you don't need to latch them etc etc - you just go grab the data and
you're done.
Interestingly, Oracle seem to have "given up" on people's predilection with
unneccesarily querying
from dual. In v10, there's a new optimization which skips the query to dual
altogether.
Cheers
Connor
--- ryan_gaffuri@xxxxxxxxxxx wrote:
> does anyone know why x$dual has the reduce overhead? How is Oracle managing
> the memory
> structure? Most x$tables incur serious performance problems. I would be
> hesitant to use it,
> unless I knew more about what was going on internally.
> -------------- Original message --------------
>
=====
Connor McDonald
Co-author: "Mastering Oracle PL/SQL - Practical Solutions"
ISBN: 1590592174
web: http://www.oracledba.co.uk
web: http://www.oaktable.net
email: connor_mcdonald@xxxxxxxxx
Coming Soon! "Oracle Insight - Tales of the OakTable"
"GIVE a man a fish and he will eat for a day. But TEACH him how to fish,
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