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Apache Hive - Single pass through query

Question asked by Lokesh on Aug 4, 2017
Latest reply on Aug 4, 2017 by MichaelSegel

Hi All,

 

I got this question from w3ii.com but finding it difficult to understand.

 

Query A:

hive> INSERT OVERWRITE TABLE sales SELECT * FROM history WHERE action = 'purchased';

hive> INSERT OVERWRITE TABLE credits SELECT * FROM history WHERE action = 'returned';

 

and Query B:

hive> FROM history

INSERT OVERWRITE sales SELECT * WHERE action = 'purchased' 

INSERT OVERWRITE credits SELECT * WHERE action = 'returned'

 

Which of them will make a single pass through?

A - Query A

B - Query B (This is the answer)

C - Both

D - None

 

I don't know if query B will even compile. There is no 'select * from table_name'. What is single pass through? Can somebody please explain this concept in detail taking above query as an example?

 

Regards,

Lokesh

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