IIRC, it makes no difference to the cost based optimizer what order the expression in the where clause are. I seem to recall that the old rule based one was sensitive to order of predicates in the where clause but that is not used in general anymore. It rarely pays to try to outsmart the optimizer unless you know a great deal about the data you are working with and are able to use hints to give it a little prod along the right path.
weird0 wrote: > You mean.... Rely on SQL Plus....... > > And it depends... not necessary the joining conditions or the fields > first > > On Nov 10, 11:33 pm, "MW Mann" <[EMAIL PROTECTED]> wrote: > >> Run explain plans on both to find out- I you are not familiar doing these in >> SQL Plus (although there is plenty resource material out there), most tools >> TOAD, PL\SQL developer etc have these. I suggest using oracle's free sql >> developer. Its great. >> It depends what optimizer your database is running, but its likely that it >> wont make a difference in this case. >> >> Always use explain plan though with these types of questions, not only will >> it give you the answer, but also get you more familiar with tuning and >> optimization, which I think is a huge and essential skill to have. >> >> Hope that helps. >> >> mike >> >> >> >> On Mon, Nov 10, 2008 at 5:54 PM, weird0 <[EMAIL PROTECTED]> wrote: >> >> >>> Would be it a more optimizable sol. to apply the joining conditions >>> first or apply the restrictions on fields like male gender. >>> >>> I believe applying the restrictions first, to min. the table and then >>> to join the tables is more optimized way. >>> >>> For example:- >>> >>> More optimized >>> -------------------- >>> >>> select a.col1,b.col1,c.col1 >>> from tbl_1 a, tbl_2 b, tbl_3 c >>> where a.gender='Male' >>> and a.type='Animal' >>> and a.id=b.id >>> and a.id=c.id >>> >>> Less optimized >>> ---------------------- >>> select a.col1,b.col1,c.col1 >>> from tbl_1 a, tbl_2 b, tbl_3 c >>> where a.id=b.id >>> and a.id=c.id >>> and a.gender='Male' >>> and a.type='Animal' >>> >>> Kindly, respond and give me refer me additional comprehensive good >>> links about >>> Query Optimizations. >>> >> -- >> Michael Mann >> > > > --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Oracle PL/SQL" group. To post to this group, send email to Oracle-PLSQL@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/Oracle-PLSQL?hl=en -~----------~----~----~----~------~----~------~--~---
