Hi Günther, > I need to join 2 tables A and B on 3 columns, ie. > > "select A.4, B5 where A1 = B1 and A2 = B2 and A3 = B3" > > the columns B1, B2, B3 are individually indexed, I also have an > index of > (B1,B2,B3).
> The query is very slow, I don't understand why, can someone please > tell > me where my mistake is? You don't need the individual indexes for that query. You need an index on (B1, B2, B3) as well. So in all you need: create table A (A1, A2, A3, A4, A5); create table B (B1, B2, B3, B4, B5); create index AI on A (A1, A2, A3); create index BI on B (B1, B2, B3); Your select statement looks odd to me. I guess you mean: select A4, B5 from A, B where A1 = B1 and A2 = B2 and A3 = B3; or: select A4, B5 from A join B on A1 = B1 and A2 = B2 and A3 = B3; HTH, Tom _______________________________________________ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
