Hive functions
Command :
SHOW FUNCTIONS (to see all in-built functions)
- To show Complete details of in-built function.
Descibe function concat
Calling Functions:
Select concat(fname,lname) as fullname from emp
Functions Types
1. Standard Functions : round(), floor(), abs(), reverse(), cocat() , ucase()
2. Aggregate , Functions:Sum(), avg(), min(),max()
3. Table Generating Functions:explode(),array()
Types of UDF
- 1. Regular UDF: operates on a single row and produces a single row as its output.
- 2. User Defined Aggregate functions: works on multiple input rows and creates a single output row.
- 3. User defined table generated functions: operates on a single row and produces multiple rows—a table—as output.
Conditions of UDF
- • A UDF must be a subclass of org.apache.hadoop.hive.ql.exec.UDF.
- • A UDF must implement at least one evaluate() method.