Hello, My English is not very good but try to communicate ... At about the creation of composite or simple index. Doubts: 1- If I create a composite index and then, in a join, I realize bases crossing using only one of the fields present in my composite index, this is not very performative, correct? In the future I'll use others fields presents in this composite index but at the present moment, in a determined join that I have to do, only one of the fields involved in this composite index I really need to use. It would be the best way if I create an index only for the field that I want to use now and create another (a second) composite index for the fields that will be used in the future? 2- The second doubt involves the following situation ... have a base of 30,000 records that will be my main base on a left join, the other base, that is may right side in this left join, has no less than 187 million records ... the second contain CPF (it's the name of field that we use in Brazil to identify a person... like a ID...) ... my question is ... the customer does not know yet that they wants to extract, what kind of information they'll use... I think that instead of crossing a giant base like this ... I should use a copy of this giant base but divided into periods, example ... base1, base2, base3, or even a copy that already contain deleted inactive customers ... but as I said ... the problem that I have is the customer will still decide what information they prefer to work for example, for campaign of marketing in future... but .... to cross 30,000 records (my left base in left join) with 187 million records (my right base), even using a index, it' ll take an eternity, I'm correct?
Thanks all.
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