[jira] [Created] (TAJO-939) Refactoring the column resolver in LogicalPlan

["Hyunsik Choi (JIRA)" <ji...@apache.org>]

Hyunsik Choi created TAJO-939:
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             Summary: Refactoring the column resolver in LogicalPlan
                 Key: TAJO-939
                 URL: https://issues.apache.org/jira/browse/TAJO-939
             Project: Tajo
          Issue Type: Bug
          Components: planner/optimizer
            Reporter: Hyunsik Choi
            Assignee: Hyunsik Choi
             Fix For: 0.9.0


The main role of the column resolver is to find the exact column in a relation or a temporal column to which a variable name points. We have used a monolithic column resolver to deal with lots of cases.

But, resolving a name should play different roles according to at which the name is placed. 

For example, 1) a column name in select list always points one of fields in relations, 2) a column name in WHERE clause can point to one of fields in relations or one of aliased temporal fields in select list. If there are duplicated, the column name firstly chooses the field in relations. 3) a column name in ORDER BY clause is similar to that in WHERE clause, but it firstly chooses one of aliased temporal fields in select list.



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