aa8d7cd2_Cost_Based_Oracle_Fundamentals__Comments
[Chapter] Chapter 12 [Title] Hash Joins [Comments] 
Although the hash join appeared in Oracle long after the sort/merge join, I’ve tackled it before the sort/merge – partly because it’s easier to deal with, partly because it seems to be used so much more than the sort/merge in modern systems. In this chapter, we see that the model doesn’t really match the run-time mechanism; moreover that the cost calculations change quite sharply with version and enabled features.
Cost Based Oracle Fundamentals
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