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From Jeszy <>
Subject Re: How many threads impala start for handling partitioned join?
Date Wed, 25 Oct 2017 14:08:33 GMT
Hello JJ,

No, currently Impala uses one thread to execute the join (without
regard for the amount of partitions that fit into memory).


On 25 October 2017 at 05:44, 俊杰陈 <> wrote:
> Hi
> When Impala does a partitioned join on a node, it split the build input
> into partitions until a partition can fit into memory and consume the probe
> input then do the join and output rows.
> My question is will impala schedule multiple tasks to do join if multiple
> partitions fit into memory, or iterate over partitions? And for one
> partition does it use multiple threads to do join?  Thanks in advanced.
> JJ

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