Hello, I am using sqlite3 (3.7.15.2 at the moment) in a project.
I discovered that the order of columns in a group by affects the performance of a query. Is this expected? For example: Table: Column A int, Column B int, Column C int One Index: A,B (combined) Query 1: SELECT A,B,count(*) from tableTest group by A,B Query 2: SELECT A,B,count(*) from tableTest group by B,A Query 1 will use the index, while query 2 will not. (which makes Query 1 a lot faster with bigger tables). Both querys will result with the same data. I do not really understand why it doesn't use the index for both querys. I am also using a virtual table (based on a two dimensional array) (very nice feature btw, sad that it is so unknown). I am seeing the same behaviour there. It will only use the index if it has the exact same order as the columns in the group by. Thanks, Daniel _______________________________________________ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
