I understand similar sharing as : - Exact sharing for the columns histogram. - Exact sharing for the columns used as range predicates(between, >=, >, <=, <, ...) - Force sharing for the columns none of aboves Similar sharing with the histogramed-columns and/or ranged-columns would generate tons of child cursors and reparse would occur for each child cursor. ================================ Dion Cho - Oracle Performance Storyteller http://dioncho.wordpress.com (english) http://ukja.tistory.com (korean) http://sites.google.com/site/otpack (tpack) ================================ 2010/11/30 Ram Raman <veeeraman@xxxxxxxxx> > > Thanks for the pointer Carol. > > I was reading up on the ML note and I saw this: "This parameter is > generally overly restrictive in what it actually allows to be shared. > SIMILAR tells oracle to try and share cursors by replacing all literals with > binds for legacy applications, but directs that sharing only be performed > when all the replaced literal values were exactly the same (in the case of > predicates referencing columns with histograms or using inequality operators > such as BETWEEN, <, and !=) " > > I am confused by what "but directs that sharing only be performed when all > the replaced literal values were exactly the same" means. I thought SIMILAR > would make Oracle use the already existing plan without having to reparse in > case of **different** literal values. Is that the right understanding of > 'sharing of the cursor' ? If sharing is performed only when replaced literal > values are the exactly same, wouldnt that make it EXACT and not SIMILAR? > > Thanks. > > 2010/11/25 <Laimutis.Nedzinskas@xxxxxx> > >> nice, one more AI decoration gone. >> >> >> >> --------------------------------------------------------------------------------- >> >> Please consider the environment before printing this e-mail >> >> >> >> Carol Dacko >> <dackoc@xxxxxxxxx >> > To >> Sent by: Oracle-L Freelists >> oracle-l-bounce@f <oracle-l@xxxxxxxxxxxxx> >> reelists.org cc >> >> Subject >> 2010.11.23 18:49 Thank you Oracle Support - >> cursor_sharing = similiar is >> deprecated! >> Please respond to >> dackoc@xxxxxxxxx >> >> >> >> >> >> >> >> >> Maybe I am the last person to the know but Doc ID: 1169017.1 is the >> announcement that cursor_sharing = similar is now deprecated in 11g! And >> the write up is very good. And it is great that they also included in the >> references the Optimizer Team's blog about it too. >> >> So yes, thank you Oracle Support! I really do appreciate this! This will >> now be one more battle I don't need to fight! >> >> Warm regards, >> Carol Dacko >> University of Michigan >> >> >> >> -- >> //www.freelists.org/webpage/oracle-l >> >> >> >