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Hive supports SORT BY which sorts the data per reducer. The difference between "order by" and "sort by" is that the former guarantees total order in the output while the latter only guarantees ordering of the rows within a reducer. If there are more than one reducer, "sort by" may give partially ordered final results.

Note: It may be confusing as to the difference between SORT BY alone of a single column and CLUSTER BY. The difference is that CLUSTER BY partitions by the field and SORT BY if there are multiple reducers SORT BY partitions randomly in order to distribute data (and load) uniformly across the reducers.

Basically, the data in each reducer will be sorted according to the order that the user specified. The following example shows

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