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would pick out half of the 3rd cluster as each bucket would be composed of (32/64)=1/2 of a cluster.
For information about creating bucketed tables with the CLUSTERED BY clause, see Create Table (especially Inserting Data into Bucketed Tables) and Bucketed Tables.
Block Sampling
Block sampling is available starting with Hive 0.8. Addressed under JIRA - https://issues.apache.org/jira/browse/HIVE-2121
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