private RexToJavaCompiler createExpressionCompiler(RelRoot relRoot) {
    RelDataTypeFactory dataTypeFactory = relRoot.project().getCluster().getTypeFactory();
    RexBuilder rexBuilder = new SamzaSqlRexBuilder(dataTypeFactory);
    return new RexToJavaCompiler(rexBuilder);
  }
Since Drill has different mechanism and rules for implicit casting,
ensureType() is overridden to avoid conflicting cast functions being added to the expressions.
samza-sql/src/main/java/org/apache/samza/sql/translator/TranslatorContext.java