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From Serhii-Harnyk <...@git.apache.org>
Subject [GitHub] drill pull request #748: DRILL-5263: Prevent left NLJoin with non scalar sub...
Date Tue, 14 Feb 2017 17:02:10 GMT
Github user Serhii-Harnyk commented on a diff in the pull request:

    https://github.com/apache/drill/pull/748#discussion_r101086894
  
    --- Diff: exec/java-exec/src/main/java/org/apache/drill/exec/planner/physical/NestedLoopJoinPrule.java
---
    @@ -49,7 +49,7 @@ protected boolean checkPreconditions(DrillJoinRel join, RelNode left,
RelNode ri
           PlannerSettings settings) {
         JoinRelType type = join.getJoinType();
     
    -    if (! (type == JoinRelType.INNER || type == JoinRelType.LEFT)) {
    +    if (!(type == JoinRelType.INNER || (type == JoinRelType.LEFT && JoinUtils.hasScalarSubqueryInput(left,
right)))) {
    --- End diff --
    
    In the case when table joining with the result of the query with aggregate function, Drill
creates physical plan with left nested loop join.
    It is due to this code line:
    https://github.com/mapr/incubator-calcite/blob/DrillCalcite1.4.0/core/src/main/java/org/apache/calcite/sql2rel/SqlToRelConverter.java#L1078
    So to allow execution of such queries without changes in calcite - allow left nested loop
join for scalar subqueries.


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