[Monetdb-developers] semantics of aggregation operations

S.Idreos at cwi.nl S.Idreos at cwi.nl
Thu May 18 15:35:53 CEST 2006


Hi all,

I would like to open a discussion on the semantics of  operations.

I just noticed for example that the sum operation will return nil if one
or more of the BUNs in the BAT is nil.

That is probably not the semantics that someone would expect, i.e., I
would like to see the actual result by ignoring the nils.

Given the current semantics the code that SQL generates has to first
remove nils (with a select operation) and then apply the sum operation on
a BAT. That costs more time and also results in one more intermediate
result.

What about updating the sum implementation to ignore nils? How much would
affect that the various projects on top of MonetDB?

Regards,
Stratos




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