Implement non-staged MapJoin

select a.* from src a join src b on a.key=b.key;

STAGE PLANS:
  Stage: Stage-4
    Map Reduce Local Work
      Alias -> Map Local Tables:
        a 
          Fetch Operator
            limit: -1
      Alias -> Map Local Operator Tree:
        a 
          TableScan
            alias: a
            HashTable Sink Operator
              condition expressions:
                0 {key} {value}
                1 
              handleSkewJoin: false
              keys:
                0 [Column[key]]
                1 [Column[key]]
              Position of Big Table: 1

  Stage: Stage-3
    Map Reduce
      Alias -> Map Operator Tree:
        b 
          TableScan
            alias: b
            Map Join Operator
              condition map:
                   Inner Join 0 to 1
              condition expressions:
                0 {key} {value}
                1 
              handleSkewJoin: false
              keys:
                0 [Column[key]]
                1 [Column[key]]
              outputColumnNames: _col0, _col1
              Position of Big Table: 1
              Select Operator
                File Output Operator
      Local Work:
        Map Reduce Local Work
  Stage: Stage-0
    Fetch Operator

  Stage: Stage-3
    Map Reduce
      Alias -> Map Operator Tree:
        b 
          TableScan
            alias: b
            Map Join Operator
              condition map:
                   Inner Join 0 to 1
              condition expressions:
                0 {key} {value}
                1 
              handleSkewJoin: false
              keys:
                0 [Column[key]]
                1 [Column[key]]
              outputColumnNames: _col0, _col1
              Position of Big Table: 1
              Select Operator
                  File Output Operator
      Local Work:
        Map Reduce Local Work
          Alias -> Map Local Tables:
            a 
              Fetch Operator
                limit: -1
          Alias -> Map Local Operator Tree:
            a 
              TableScan
                alias: a
          Has Any Stage Alias: false
  Stage: Stage-0
    Fetch Operator