RE: Risk of RULE mode in 10g+
- From: "Rich Jesse" <rjoralist@xxxxxxxxxxxxxxxxxxxxx>
- To: oracle-l@xxxxxxxxxxxxx
- Date: Mon, 15 Mar 2010 14:43:22 -0500 (CDT)
Hey Dick,
> OH Dear, I'll try to find the url that says this for you, but in 10g
> the rule based optimizer isn't deprecated, it's dead period. You can
> put rule in there all you want, but it will run in cost mode. Isn't
> suppose to cause problems with the result set that I've heard of, nor
> does it cause a problem with executing the sql.
On my 10.1.0.5.0 instances (with COMPATIBILITY set the same), this statement
explains and runs *much* better with RULE:
SELECT /*+ rule */
COUNT(*)
FROM v$rman_status
WHERE row_type = 'COMMAND'
AND operation = 'BACKUP'
AND status = 'COMPLETED'
AND start_time >= SYSDATE-1/24
AND command_id LIKE '%ARCH%'
AND sid = 0;
On my sole 10.2.0.3.0 instance, I don't perceive a difference although
autotrace consistently shows 13 memory sorts when using RULE versus only 1
without, giving empirical evidence that RULE is still (barely?) alive in
10g.
I'd be interested to see that article! :)
Rich
--
//www.freelists.org/webpage/oracle-l
Other related posts:
