Major Description
Drill's documentation contains many references to the names "INTERVALYEAR" and "INTERVALDAY", usually referring to them as if they were SQL types.
However, although those names do exist in Drill internally and in programmatic interfaces, they are not SQL datatype names. (They are names of internal objects representing data types and internal names of those represented types, but they are not SQL data type names, and are not exposed in the SQL layer (e.g., "... CAST (... AS INTERVALYEAR) ..." is not accepted).)
For most references like "INTERVALYEAR and INTERVALDAY," which refer to what the SQL specification calls "interval data types" (e.g., in ISO/IEC 9075-2:2011(E) section 4.6.1), the documentation should instead say something like "interval types" or "interval data types" (or possibly "INTERVAL types").
For most references to "INTERVALYEAR" only, the documentation should say something like "year-month interval type" or "year-month intervals" (based on usage in ISO/IEC 9075-2:2011(E) sections 4.6.1 and 4.6.3).
Similarly, most references to "INTERVALDAY" only should refer to "day-time interval types," etc.