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From Jeszy <jes...@gmail.com>
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).

HTH

On 25 October 2017 at 05:44, 俊杰陈 <cjjnjust@gmail.com> 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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