Hi all, As I recall, as long as the value to the left of the "=" matches a key, then Rushmore will use it.
So if you use a compound key (index on city + state + padl(allt(str(radius)),6,'0') tag MyTag) , it will only be fast if you use something like: Select * from MyTable where city + state + padl(allt(str(radius)),6,'0') = "some value with padded spaces, etc." In most cases, this would be silly. But there are exceptions - yours is not apparently one of them as indexes on the individual fields will always be faster. Keep in mind that if you have an index on radius or even str(radius), the following still will not be optimized: Select * from MyTable where padl(allt(str(radius)),6,'0') = " 342342" You would have to actually have an index build on padl(allt(str(radius)),6,'0') - not very useful. The key question is, once you have filtered by city and state, how many records will you then have? If many (>10,000 or so), then an additional filter option might help. But VFP can filter 10,000 (and usually much more) records very fast, even without indexes - so only testing would help. Anyway, hope things worked out for you, Fletcher Fletcher Johnson fletchersjohn...@yahoo.com LinkedIn.com/in/FletcherJohnson beknown.com/FletcherJohnson twitter.com/fletcherJ strava.com/athletes/fletcherjohnson 408-946-0960 - work 408-781-2345 - cell -----Original Message----- From: ProFox [mailto:profox-boun...@leafe.com] On Behalf Of Frank Cazabon Sent: Friday, November 3, 2017 5:22 PM To: profox@leafe.com Subject: Re: Reminder about VFP compound indexes and best strategy Individual indexes on each field should work, not an index on the compound expression. On 3 November 2017 17:09:39 GMT-04:00, mbsoftwaresoluti...@mbsoftwaresolutions.com wrote: >VFP9SP2 free table > >I've got a table with this structure: > >city c(30) >state c(2) >radius i >distance i > >My query is looking for city, state, and radius, to get back those >whose distance is <= InputParameter. > >select * > from MyTable > where city = m.tcCity and state = m.tcState and radius <= m.tiRadius > >Not sure if I should >index on city tag city >index on state tag state >index on radius tag radius > >or > >index on city + state + padl(allt(str(radius)),6,'0') tag MyTag > >??? > >I know I can use SYS(3054) to get my answer but I'm getting ready to be > >away from the office for a bit and was hoping someone knew the obvious >answer. Otherwise I'll run my testing later tonight. > >(At the very least, hopefully somebody learned about SYS(3054,x,y) >today.) > [excessive quoting removed by server] _______________________________________________ Post Messages to: ProFox@leafe.com Subscription Maintenance: http://mail.leafe.com/mailman/listinfo/profox OT-free version of this list: http://mail.leafe.com/mailman/listinfo/profoxtech Searchable Archive: http://leafe.com/archives/search/profox This message: http://leafe.com/archives/byMID/profox/056301d359b1$ce55a880$6b00f980$@yahoo.com ** All postings, unless explicitly stated otherwise, are the opinions of the author, and do not constitute legal or medical advice. This statement is added to the messages for those lawyers who are too stupid to see the obvious.
