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https://issues.apache.org/jira/browse/TAJO-939?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14060551#comment-14060551
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ASF GitHub Bot commented on TAJO-939:
-------------------------------------

Github user jihoonson commented on a diff in the pull request:

    https://github.com/apache/tajo/pull/71#discussion_r14873320
  
    --- Diff: 
tajo-core/src/main/java/org/apache/tajo/engine/planner/LogicalPlanner.java ---
    @@ -1192,8 +1204,12 @@ public ScanNode visitRelation(PlanContext context, 
Stack<Expr> stack, Relation e
         Set<String> newlyEvaluatedExprsReferences = new 
LinkedHashSet<String>();
         for (Iterator<NamedExpr> iterator = 
block.namedExprsMgr.getIteratorForUnevaluatedExprs(); iterator.hasNext();) {
           NamedExpr rawTarget = iterator.next();
    +//      if (rawTarget.getExpr().getType() == OpType.Column) {
    --- End diff --
    
    Please remove commented out codes.


> 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.
> The current column resolver does not consider the above rules. As a result, 
> it works incorrectly in some cases where a sql statement includes the same 
> name references, actually indicating one field in relation and one aliased 
> temporal field in select list. We should fix it.



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