aa8d7cd2_Cost_Based_Oracle_Fundamentals__Comments
[Chapter] Chapter 13 [Last addendum] 1st Dec 2009 [Title] Sorting and Merge Joins [Comments] 
Sort/Merge joins exhibit features that you can’t get with hash joins. You can do Cartesian merge joins (and sometimes the optimizer does, even when you don’t think your SQL is supposed to); and you can do range-based joins with sort/merge joins. The cost calculations for such things show some surprising behavior. But sort/merge joins are just like hash joins in some ways: the cost calculations don’t match the run-time mechanism, and the results change dramatically with version and enabled features.
Cost Based Oracle Fundamentals
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