[jira] [Created] (IMPALA-11163) To scan small dimensional tables, the number of nodes selected by FE can be less

["Qifan Chen (Jira)" <ji...@apache.org>]

Qifan Chen created IMPALA-11163:
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             Summary: To scan small dimensional tables, the number of nodes selected by FE can be less
                 Key: IMPALA-11163
                 URL: https://issues.apache.org/jira/browse/IMPALA-11163
             Project: IMPALA
          Issue Type: Improvement
            Reporter: Qifan Chen


In Impala, FE determines the # of exec nodes to use for scan based on the # of local/remote nodes hosting data blocks. For example for a dimensional table,  assume its #local nodes = 3, and its #remote nodes = 17. Then # of exec nodes for scan is 20. The final value is min(20, #exec nodes in cluster).

In the case of a partitioned join(f, d) where f is the fact table and d is the dimensional table, the # of network opens from join to table d can be made less (say 2 instead of 20). Therefore, the system can handle more # of queries.



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