Kurt Young created FLINK-5185:
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             Summary: Decouple BatchTableSourceScan with TableSourceTable
                 Key: FLINK-5185
                 URL: https://issues.apache.org/jira/browse/FLINK-5185
             Project: Flink
          Issue Type: Improvement
          Components: Table API & SQL
    Affects Versions: 1.2.0
            Reporter: Kurt Young
            Assignee: zhangjing
            Priority: Minor


As the components' relationship show in this design doc:
https://docs.google.com/document/d/1PBnEbOcFHlEF1qGGAUgJvINdEXzzFTIRElgvs4-Tdeo/
We found it's been annoying for BatchTableSourceScan directly holding 
TableSourceTable, and refer to TableSource further. It's ok if the relationship 
is immutable, but when we want to change the TableSource when applying 
optimizations, it will cause some conflicts and misunderstanding. 

Since there is only one way to change TableSource, which is creating a new 
TableSourceTable to hold the new TableSource, and create a new 
BatchTableSourceScan pointing to that TableSourceTable which just created. The 
annoying part is the RelOptTable comes from the super class TableScan still 
holds the connection to the original TableSourceTable and TableSource. It will 
cause some misunderstanding, which one should the Scan rely to, and what's 
difference between these tables. 

Besides, TableSourceTable is not very useful in BatchTableSourceScan, the only 
thing Scan cares is the RowType it returns, since this is and should be decided 
by TableSource. So we can let BatchTableSourceScan directly holding TableSource 
instead of holding TableSourceTable.If some original information are needed, 
find table through RelOptTable. 




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