Q:
There are several types of builtin Hive Functions.

String Functions
 concat() used for concatenation.
 lower()/upper()  to convert upper to lower and viceversa.
 trim()  to remove whitespaces.

Date Functions
 todate()  to convert string to date format.
 year()/month()/day()  to retieve the year,month,day respectively.

Mathematical Functions
 round()/rand()  to get the round off value, generate sequence of random numbers respectively.
 sqrt()/abs()  to get the square root and absolute value of the operation respectively.

Collection Functions
 size(Map<K.V>)  will represent elements number in map type.
 size(Array<T>)  will represent elements in array type.

Conditional Functions