LiuJi created FLINK-11425:
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             Summary: Support of “Hash Teams” in Hybrid Hash Join
                 Key: FLINK-11425
                 URL: https://issues.apache.org/jira/browse/FLINK-11425
             Project: Flink
          Issue Type: New Feature
          Components: Core, Optimizer
            Reporter: LiuJi


Hybrid Hash Join is already supported in current version. The join starts 
operating in memory and gradually starts spilling contents to disk, when the 
memory is not sufficient.

 

Current hash join only support two inputs,  so when a job contains multiple 
hash joins which have the same join keys, it will consume some unnecessary 
resources (I/O, memory, etc) because some upstream output data may useless for 
downstream hash join.

 

According to the above observations, we want to provide a HashTeamManager to 
implement multiway inputs hash join by combining several two way hash join 
which have same join keys. HashTeamManager manage the relations of multiple 
HashTables and improve efficiency in memory use and lower I/O operations by 
joining multiple relations at one time.



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