Why is the Parquet read optimization not on by default? Optimizing Reads of Parquet-Backed Tables
Use the store.hive.optimize_scan_with_native_readers option to optimize reads of Parquet-backed external tables from Hive. When set to TRUE, this option uses Drill native readers instead of the Hive Serde interface, resulting in more performant queries of Parquet-backed external tables. (Drill 1.2 and later) Set the store.hive.optimize_scan_with_native_readers option as described in the section, "Planning and Execution Options" <http://kristinehahn.github.io/drill/docs/planning-and-execution-options/>.
