Query optimizer module?

Are there tools out there to allow me to build a query optimizer? My idea is that it accepts as input a description of the logical algebra, of the physical algebra, of the various equivalence relations, some cost factors and selectivity heuristics, and off we go...

Note that I'm _not_ using the relational algebra, so it's important for me to be able to use it for a different algebra than just the relational one.

Of course, if there is a query optimizer construction kit which requires me to do some programming, that's also fine.

tia,
kai

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