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Home -> Community -> Mailing Lists -> Oracle-L -> RE: Cost vs Rule
Interesting point . . . but the flip side of your argument is that by
putting hints in we, as the vendor, while not "requiring" you to use CBO
(since RBO will just ignore the hints) are saying, 'Hey, you had BETTER use
CBO if you want this thing to work the way we've designed it'
interesting to continue this discussion thread, although it's separate from the tuning issue I need to look at
-biill
-----Original Message-----
Sent: Thu, March 07, 2002 2:44 PM
To: Multiple recipients of list ORACLE-L
Bill - Are you saying that you switched to RBO for everything? I thought the
better procedure would be to remain CBO and put hints into individual SQL
queries. Is this a possibility in your environment? You mention that you are
a development shop. Does this mean that you create software and sell it to
others? Personally, I wouldn't be pleased if my company purchased some
software and found it required me to switch my database to RBO.
Dennis Williams
DBA
Lifetouch, Inc.
dwilliams_at_lifetouch.com
-----Original Message-----
Sent: Thursday, March 07, 2002 1:23 PM
To: Multiple recipients of list ORACLE-L
I work in a dev shop - most of the sql is canned and pretty basic. We've
been running CBO in all of our dev environments, but we have a few long txns
that just take forever. At the request of some savvy developers, I turned
on RBO, and it brought down execution times dramatically.
I've been analyzing affected tables often (we do a lot of bulk load/unload
for testing), and have played with partitioning and clustering, particularly
on one table that's just a dog. CBO will always do a FTS where RBO uses the
PK to retrieve data.
Where to go next? I've been unable to alter the costs dramatically enough
to make any real difference in execution time.
thx
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Author: Magaliff, Bill
INET: Bill.Magaliff_at_lendware.com
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Author: DENNIS WILLIAMS
INET: DWILLIAMS_at_LIFETOUCH.COM
Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051 San Diego, California -- Public Internet access / Mailing Liststo: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).
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