private static Table createTableFromRelSchema(RelDataType relationalSchema) {
    return new AbstractTable() {
      public RelDataType getRowType(RelDataTypeFactory typeFactory) {
        return relationalSchema;
      }
    };
  }
QueryPlanner that uses calcite engine to convert the sql query to relational graph.
samza-sql/src/main/java/org/apache/samza/sql/planner/QueryPlanner.java