Cardinality was: cardinalism

I'm not Joe, but here's my two cents.

It depends on how the optimizer in the database engine works.

In Oracle Rdb since auld lang syne, and in Oracle RDBMS since version 7.x, there is a cost based optimizer.

In the cost based optimizer, the selectivity of an index is a very important consideration. Tables with large cardinality are more likely to have highly selective indexes than tables with small cardinality. This is a gross oversimplification, but maybe you get the idea.

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>What role does cardinality play as a criterion for selecting the
>indexes, and performance tuning?
Received on Mon Jul 10 2000 - 00:00:00 CEST