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aggregation in mysql
Posted by: luca ghionna
Date: February 27, 2010 11:03AM

Hello there!

my question is related to the way mysql optmizes aggregate/group-by queries. Very conventional systems usually perform the evaluation of all joins in the query and then apply on the resulting table the requested aggregation(s)/group-by. However, one can easily perform smarter methods, e.g., in many cases multiple "early" aggregations can be used to reduce the size of intermediate relations as well as to count the overall number of tuples needed to solve a particular aggregate. What about mysql? Which kind of optimization for aggregation is provided?

Thank you,

have a nice day.

Luca.

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