|Subject||Re: Performance question|
> However, in the case in point, you probably have only twoI tested it on a table with 5'000'000 records.
> distinct values for GENDER, and no more than eight for COURSE.
> In a large table, indexes on those fields will have poor
> selectivity. So, a combined field might work. Test it on
> a large database before you commit yourself to a plan that
> makes the data harder to use and understand.
1) where SR.STYLEID = 8 and SR.COURSE = 2 and SR.GENDER = 1
2) where SR.COURSEGENDERSTYLE = 131336
the differences to run the query and fetch all records (about 50'000)
So I think, I will not put the values in on combined INTEGER field.
But my question is, if there is a type for an 8bit number in Firebird,
since COURSE and GENDER have less than 10 different values.