I believe that it is incorrect that it will intersect indexes. I understand that some people think this might be preferable, but I do not believe this logic has ever been coded in.
-----Original Message----- From: Charles Stevenson <stevenson.c...@gmail.com> To: U2 Users List <u2-users@listserver.u2ug.org> Sent: Tue, Oct 25, 2011 3:08 pm Subject: Re: [U2] UniBasic Question RetrieVe will use an index if it can, regardless of the order of the election criteria (& if not select list is already active). etrieVe will now do intersections of index reults if 2 indexed election criteria are specified. 'm not sure when or how good it does that. O.OPTIMIZE can override these attempts by RetrieVe. O.INDEX will prevent indexes being used. On 10/25/2011 5:00 PM, Steve Romanow wrote: I think we are bike-shedding this now :) I seem to recall that if the indexed field is _before_ the non indexed field, its benefit is not lost. I have not looked close at that in a long time. On Tue, Oct 25, 2011 at 5:42 PM, Woodward, Bob <bob_woodw...@k2sports.com> wrote: > Add a second selection criteria and the benefit of the index is washed > out. > > -----Original Message----- > From: u2-users-boun...@listserver.u2ug.org > [mailto:u2-users-boun...@listserver.u2ug.org] On Behalf Of Charles > Stevenson > Sent: Tuesday, October 25, 2011 2:39 PM > To: U2 Users List > Subject: Re: [U2] UniBasic Question > > True on UV, too. > Compare output of these using EXPLAIN keyword: > LIST FILE WITH indexed_field = "soemthing" EXPLAIN > LIST FILE WITH indexed_field = "soemthing" EXPLAIN NO.INDEX > > Or forget EXPLAIN, but do it with a large file and notice the speed > differnce. > > On 10/25/2011 4:29 PM, charles_shaf...@ntn-bower.com wrote: >>>> I don't know if I agree that SELECT is faster. If you are using >>>> indexed fields, SELECT is definitely not the good choice. >> Are you saying that when there is an index, the system does not need > to >> read the record at all? It just gets the SELECT list from the index? > Is >> this only true in Unidata? >> _______________________________________________ 2-Users mailing list 2-us...@listserver.u2ug.org ttp://listserver.u2ug.org/mailman/listinfo/u2-users _______________________________________________ U2-Users mailing list U2-Users@listserver.u2ug.org http://listserver.u2ug.org/mailman/listinfo/u2-users
