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Mappers all on the same node?

Mappers all on the same node?

New Contributor

Hi,

I have a cluster of 3 datanodes and I'm launching a Hive query on MR.

The query is a join between two tambles which spawns 3 mappers.

Doubts:

 - the 3 mappers are all running on the same node. Is this normal?

 - the specified node is only using about 40$ of his CPU and the job takes ages to complete. Why? Considering the two tables I use are 3 blocks and 1 block respectively.

 

Any ideas? Thanks

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