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TEZ - How to enable Fetch Task instead of MapReduce Job for simple query in Hive

By Dinesh

 

Certain simple Hive queries can utilize fetch task, which can avoid the overhead of starting MapReduce job.

hive.fetch.task.conversion

This parameter controls which kind of simple query can be converted to a single fetch task.
Value "none" is added in Hive 0.14 to disable this feature
Value "minimal" means SELECT *, FILTER on partition columns (WHERE and HAVING clauses), LIMIT only.

hive.fetch.task.conversion.threshold

This parameter controls input threshold (in bytes) for applying hive.fetch.task.conversion.

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