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The default value for hive.auto.convert.join was false in Hive 0.10.0. Hive 0.11.0 changed the default to true (HIVE-3297). Note that hive-default.xml.template incorrectly gives the default as false in Hive 0.11.0 through 0.13.1.
MAPJOINs are processed by loading the smaller table into an in-memory hash map and matching keys with the larger table as they are streamed through. The prior implementation has this division of labor:
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