public void setIOCxt(IOContext ioCxt) {
    this.ioCxt = ioCxt;
  }
Set the IOContext reference so that input path can be changed.
This is needed because there can be more than one inputs at play
at a given time, however, there is one IOContext which needs
correct input path. In other joins, even when there are multiple
inputs, they are read sequentially which is not the case here.
ql/src/java/org/apache/hadoop/hive/ql/exec/tez/tools/KeyValueInputMerger.java