As hive creates schema and append on top of an existing data file. One can have multiple schema for one data file, schema will be saved in hive’s metastore and data will not be parsed or serialized to disk in given schema. When we will try to retrieve data, schema will be used. For example if we have 5 column (name, job, dob, id, salary) in the data file present in hive metastore then, we can have multiple schema by choosing any number of columns from the above list. (Table with 3 columns or 5 columns or 6 columns).
But while querying, if we specify any column other than above list, will result in NULL values.
