Here's a convincing stat for your architect:
There will be no RBO in a future version of Oracle. That version is
not far away (conjecture is perhaps as early as 10). As often
occurs, this is a case of do what we say, not what we do, since
RBO is still used in the data dictionary tables. Howev
[EMAIL PROTECTED] wrote:
>Well, since hints are implemented within comments, I would assume that other
>databases would simply ignore them. If anyone has direct experience, that
>would be interesting. Being completely database-agnostic may play against
>tuning.
>
it has been my experience that th
not much - desire is to keep sql ANSI compliant due to cross-platform issues
(want to be able to run the app on multiple db's)
-Original Message-
Sent: Thu, March 07, 2002 2:44 PM
To: Multiple recipients of list ORACLE-L
How much have you played with Oracle Hints???
-Joe
--- "Magaliff
> keep sql ANSI compliant due to cross-platform issues
> (want to be able to run the app on multiple db's)
They are telling you not to solve performance problems with hints. They
want to be ANSI compliant and run on multiple db's.
But it's OK solve performance problems by flipping the switch t
Title: RE: Cost vs Rule
Bill,
If you really want to use CBO I would have thought that the plan stability features of Oracle would be sufficient to squash any argument about predictability. I have not used these myself, but they seem to have been included because of the need to guarantee
I see a new MYTH developing, and that is that RULE is better than COST. I
have to believe that some thought has been put into the CBO. I also have to
believe that if we all switched to RULE in the next ten minutes that the
overwhelming response would not be "Wow, look at the incredible improveme
> At the request of some savvy developers, I turned
> on RBO, and it brought down execution times dramatically.
Maybe setting optimizer mode to first_rows would do the same. Then you
would still be using CBO, allowing your SQL to take advantage of
optimizations that are not available with RBO.
How much have you played with Oracle Hints???
-Joe
--- "Magaliff, Bill" <[EMAIL PROTECTED]> wrote:
> 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 requ
yes, everything analyzed.
sr tech arch has decided he wants to use RBO due to predictability in
production. not much I can do at this point, unless I can really come up
with convincing stats
-Original Message-
Sent: Wed, March 13, 2002 6:34 AM
To: Multiple recipients of list ORACLE-L
Well, since hints are implemented within comments, I would assume that other
databases would simply ignore them. If anyone has direct experience, that
would be interesting. Being completely database-agnostic may play against
tuning.
Just a thought. I suppose you analyzed all tables when yo
Bill,
In addition to the many excellent suggestions, may I also suggest generating
adequate number of histograms and using them by using literals instead of
bind variables (horrors!). You may also want to look at 9i - the CBO therein
looks at the value of the bind variables prior to parsing and c
This shouldn't be a problem, hints just look like comments to other db's.
John
[EMAIL PROTECTED] wrote:
not much - desire is to keep sql ANSI compliant due to cross-platform issues(want to be able to run the app on multiple db's)-Original Message-Sent: Thu, March 07, 2002 2:44 PMTo
by: Subject: Cost vs Rule
The following is from the Tim Gorman paper
· OPTIMIZER_INDEX_CACHING
This initialization parameter represents a percentage value, ranging between
the values of 0 and 99. The default value of 0 indicates to the CBO that 0%
of database blocks accessed using indexed access can be expected to
awesome article - tanks
-Original Message-
Sent: Thu, March 07, 2002 3:44 PM
To: Multiple recipients of list ORACLE-L
Tim Gorman wrote a good paper about using these parameters:
http://www.evdbt.com/SearchIntelligenceCBO.doc
Shaw John-P55297 wrote:
>
> have you tried adjusting opti
[EMAIL PROTECTED] wrote:
>Well, since hints are implemented within comments, I would assume that other
>databases would simply ignore them. If anyone has direct experience, that
>would be interesting. Being completely database-agnostic may play against
>tuning.
>
it has been my experience that th
just changed index_cost_adj from 100 to 1
what is index_caching?
-Original Message-
Sent: Thu, March 07, 2002 3:04 PM
To: Multiple recipients of list ORACLE-L
have you tried adjusting optimzer_index_caching and
optimizer_index_cost_adj?
-Original Message-
Sent: Thursday, March
always analyze - it's step 1 in any tuning I attempt
usually use compute, but if estimate it's at least 15 or 20%
-Original Message-
Sent: Thu, March 07, 2002 3:19 PM
To: Multiple recipients of list ORACLE-L
Well, since hints are implemented within comments, I would assume that other
da
Tim Gorman wrote a good paper about using these parameters:
http://www.evdbt.com/SearchIntelligenceCBO.doc
Shaw John-P55297 wrote:
>
> have you tried adjusting optimzer_index_caching and
> optimizer_index_cost_adj?
>
> -Original Message-
> Sent: Thursday, March 07, 2002 1:23 PM
> To:
Well, since hints are implemented within comments, I would assume that other
databases would simply ignore them. If anyone has direct experience, that
would be interesting. Being completely database-agnostic may play against
tuning.
Just a thought. I suppose you analyzed all tables when yo
have you tried adjusting optimzer_index_caching and
optimizer_index_cost_adj?
-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 e
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 c
.com>cc:
Sent by: Subject: Re: Cost vs Rule
root
not much - desire is to keep sql ANSI compliant due to cross-platform issues
(want to be able to run the app on multiple db's)
-Original Message-
Sent: Thu, March 07, 2002 2:44 PM
To: Multiple recipients of list ORACLE-L
How much have you played with Oracle Hints???
-Joe
--- "Magaliff
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 i
How much have you played with Oracle Hints???
-Joe
--- "Magaliff, Bill" <[EMAIL PROTECTED]> wrote:
> 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 requ
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 ana
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