Re: [SQL] optimizing a query over tree-like structure

2008-09-30 Thread Oliveiros Cristina
or P, just with an F. Which info is to be retrieved, exactly in this case ? Best, Oliveiros - Original Message - From: <[EMAIL PROTECTED]> To: Sent: Tuesday, September 30, 2008 3:24 PM Subject: Re: [SQL] optimizing a query over tree-like structure another idea i just got, to dec

Re: [SQL] optimizing a query over tree-like structure

2008-09-30 Thread az
another idea i just got, to decrease the number of tables in one FROM, is to represent the first-level ORs with unions. but i'm not sure how exactly to do it: are these equivalent? FROM N,ownership,mm_N2R where ( N.dbid = ownership.N OR N.dbid = mm_N2R.left AND mm_N2R.right = ownership.R OR

Re: [SQL] optimizing a query over tree-like structure

2008-09-30 Thread Oliveiros Cristina
Hi, Svil I 'd like to first fully understand the background of your problem before figurin out if I can be of any help (or not). You have a tree, of which N is the root, is this correct? Then, what are the next sublevel? F, P and R? If so, why is R linked to a sibling (F) ? And the next one? O