Hive Function Meta commands:

Show Functions - Lists Hive functions and operators
Describe Feature [feature name] - Displays a brief description of the particular feature
Describe Extended Feature [feature name] - Displays an extended description of the particular feature

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Types of hive functions:
UDF (User Defined Functions): is a function that takes one or more columns of a row as arguments and returns a single value
UDTF (Tabular User Defined Functions): This function is used to produce multiple columns or rows of output by taking zero or more inputs
Macros: It is a function that uses other functions of Hive

User-defined aggregate functions: a user-defined function that takes multiple rows or columns and returns the aggregate of the data
User-defined table generation functions: a function that takes a column from a single record and splits it into multiple rows
Indexes – Indexes are created for quick access to database columns.

Syntax: Create index <INDEX_NAME> on table <TABLE_NAME>