It depends what you mean by layout. If you add/remove/change the fields in the records, Drill can handle that. It can also handle a situation where you move from one format (say JSON) to another format (Parquet) and have mixed formats in a directory.
Drill is described as schema-free, but the data doesn't have to lack schema. Some data (Parquet, Avro) has schema, while some data (JSON, HBase, MongoDB) doesn't (ie, each record could have different fields). Drill is designed to allow queries on any data. Also, Drill leverages the structure that's embedded in the data without requiring IT to redundantly define schemas in a centralized schema repository. In other words, if there's a schema embedded in the Parquet file, why require the user to then go and maintain the same schema, explicitly, in Hive metastore?
Drill is described as schema-free, but the data doesn't have to lack schema. Some data (Parquet, Avro) has schema, while some data (JSON, HBase, MongoDB) doesn't (ie, each record could have different fields). Drill is designed to allow queries on any data. Also, Drill leverages the structure that's embedded in the data without requiring IT to redundantly define schemas in a centralized schema repository. In other words, if there's a schema embedded in the Parquet file, why require the user to then go and maintain the same schema, explicitly, in Hive metastore?