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There is only one problem with hive distict and count operating reducer

2025-01-18 Update From: SLTechnology News&Howtos shulou NAV: SLTechnology News&Howtos > Internet Technology >

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Select count (distinct *) from table

Writing like this will generate a job with only one reducer execution, which can be changed to the following:

Select count (*) from (

Select distinct * from table) t

In this way, two job can be generated, and multiple reducer can be executed, thus improving efficiency.

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