On Tue, Jul 20, 2010 at 04:43:26PM +0400, Max Vlasov scratched on the wall: > Hi, > as long as I see currently bitwise right does not use index
Doing this requires recognizing when an inverse expression exists, and then computing it. It is extremely difficult in the general case. If you want to use an index, you need to refer to a direct value. > But the first syntax is more straightforward. Having a proper column is even more straightforward. It also makes this whole issue go away and makes your indexes work correctly. > Btw, actually, sometimes when several small fields exists and they should be > indexed, one can pack them into id(rowid) to save space and the first syntax > will allow querying more naturally This breaks First Normal Form and is very un-relational. If you want the database to do what it does best, use it properly. Doing stuff like this is thinking like a C programmer, not a database programmer. In the case of SQLite, it is also very unlikely to save space. In fact, because of the way integer values are stored, it is very likely to use more space. It also screams of premature optimization. In most cases it won't save you much, if anything, and will cause all kinds of problems (like this!). You also loose the ability to index anything other than the left-most field. Finally, bit operations are not part of the SQL standard, making this kind of approach very non-portable. Many databases don't even use binary integers to store natural-number values. -j -- Jay A. Kreibich < J A Y @ K R E I B I.C H > "Intelligence is like underwear: it is important that you have it, but showing it to the wrong people has the tendency to make them feel uncomfortable." -- Angela Johnson _______________________________________________ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
