[GitHub] storm issue #1681: STORM-1444 Support EXPLAIN statement in StormSQL

[HeartSaVioR <gi...@git.apache.org>]

Github user HeartSaVioR commented on the issue:

    https://github.com/apache/storm/pull/1681
  
    FYI:
    Flink seems not support explain yet. 
    https://github.com/apache/flink/pull/2485 is proposed for adding this feature.
    
    As I described to JIRA issue, Spark supports explain and output seems to be more user friendly.
    (Note that Spark doesn't use Calcite.)
    
    ```
    scala> spark.sql("SELECT GRPID, COUNT(*) AS CNT, MAX(AGE) AS MAX_AGE, MIN(AGE) AS MIN_AGE, AVG(AGE) AS AVG_AGE, MAX(AGE) - MIN(AGE) AS DIFF FROM FOO WHERE ID > 2 GROUP BY GRPID").explain
    == Physical Plan ==
    *HashAggregate(keys=[GRPID#64], functions=[count(1), max(AGE#67), min(AGE#67), avg(cast(AGE#67 as bigint)), max(AGE#67), min(AGE#67)])
    +- Exchange hashpartitioning(GRPID#64, 200)
       +- *HashAggregate(keys=[GRPID#64], functions=[partial_count(1), partial_max(AGE#67), partial_min(AGE#67), partial_avg(cast(AGE#67 as bigint)), partial_max(AGE#67), partial_min(AGE#67)])
          +- *Project [grpid#64, age#67]
             +- *Filter (isnotnull(ID#63) && (ID#63 > 2))
                +- LocalTableScan [id#63, grpid#64, name#65, addr#66, age#67]
    ```


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