Btw, the one good use for plan stability & stored outlines are poorly written 3rd party applications, where you can't even add a hint to code. I these cases you can compose a good execution plan yourself and set your statement to use it.
Tanel. ----- Original Message ----- To: "Multiple recipients of list ORACLE-L" <[EMAIL PROTECTED]> Sent: Thursday, December 04, 2003 10:14 PM > Hi Justin > > Didn't know you were on the list > > > A properly formed hint will cause the CBO to consider the > > hinted path to be > > less costly than it would otherwise consider it, but hints do > > not force a > > query to use that particular plan. For a moderately > > complicated query, > > you'd potentially need a fair number of hints to get things > > working the way > > you want. If the statistics of the table changed, though, > > your carefully > > hinted query might well decide to take another path. Even if > > things work, > > adding hints-- particularly adding multiple hints-- to a query > > significantly increases the maintenance costs as future > > developers have to > > unravel what all the hints are doing, why they're doing it, > > whether any > > hints need to be changed as a result of the modifications, > > whether future > > changes to the CBO or new Oracle functionality should cause > > the ideal plan > > to change, etc. > > > > If you want to force Oracle to use a particular plan, plan > > stability is > > orders of magnitude easier! > > Umm, but if you look at plan stability you will see that it is > implemented as hints (and query rewrite) - typically loads of them. A > hint *does* force you to do what it says, if it is being 'ignored' then > likely you haven't excluded alternative access paths. Of course for any > sufficiently complex query (in my case that means 3 or more joins) then > manually specifying an access path with hints becomes a too difficult > problem. > > Niall > > -- > Please see the official ORACLE-L FAQ: http://www.orafaq.net > -- > Author: Niall Litchfield > INET: [EMAIL PROTECTED] > > Fat City Network Services -- 858-538-5051 http://www.fatcity.com > San Diego, California -- Mailing list and web hosting services > --------------------------------------------------------------------- > To REMOVE yourself from this mailing list, send an E-Mail message > to: [EMAIL PROTECTED] (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). > -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: Tanel Poder INET: [EMAIL PROTECTED] Fat City Network Services -- 858-538-5051 http://www.fatcity.com San Diego, California -- Mailing list and web hosting services --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: [EMAIL PROTECTED] (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).
