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From Knut Anders Hatlen <Knut.Hat...@Sun.COM>
Subject Re: Bitsets in IndexRowToBaseRowResultSet
Date Fri, 15 Dec 2006 11:13:02 GMT
Dyre.Tjeldvoll@Sun.COM writes:

> It seems to me that the constructor for IndexRowToBaseRowResultSet
> takes a bitset describing the columns coming from the heap and a
> bitset describing the columns coming from the index. But in every
> IndexRowToBaseRowResultSet one also has to compute _all_ referenced
> columns (union of heap and index bitsets), and frequently also those
> columns _only_ coming from the heap (set difference between heap and
> index).
> But the value of these "set products" seem _only_ to depend on objects
> that are fixed at compile time (in IndexToBaseRowNode), so would it
> not be cleaner (and possibly more efficient) to compute these products
> in IndexToBaseRowNode as well, and just refer to them when creating
> IndexRowToBaseRowResultSets? Or would this have some undesirable side
> effect that I'm not aware of?

I can't answer whether this is safe, but if it is, I agree that it
would be a good thing to move it to the compilation. The more
computations we can move from run time to compile time, the better, if
you ask me.

Knut Anders

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