Hive - Hadoop: The Definitive Guide - page 587

Category Type Description Literal examples

array(1, 2) [ a ]

Complex An ordered collection of fields. The fields must all be

of the same type.

ARRAY

An unordered collection of key-value pairs. Keys
must be primitives; values may be any type. For a
particular map, the keys must be the same type, and
the values must be the same type.

MAP map('a', 1, 'b', 2)

A collection of named fields. The fields may be of
different types.

STRUCT struct('a', 1,

1.0) , [ b ]
named_struct('col1',
'a', 'col2', 1,
'col3', 1.0)

A value that may be one of a number of defined data
types. The value is tagged with an integer (zero-in-
dexed) representing its data type in the union.

UNION create_union(1, 'a',

63)

[ a ] The literal forms for arrays, maps, structs, and unions are provided as functions. That is, array , map , struct , and
create_union are built-in Hive functions.

[ b ] The columns are named col1 , col2 , col3 , etc.

Primitive types

Hive's primitive types correspond roughly to Java's, although some names are influenced
by MySQL's type names (some of which, in turn, overlap with SQL-92's). There is a
BOOLEAN type for storing true and false values. There are four signed integral types:
TINYINT , SMALLINT , INT , and BIGINT , which are equivalent to Java's byte ,
short , int , and long primitive types, respectively (they are 1-byte, 2-byte, 4-byte, and
8-byte signed integers).

Hive's floating-point types, FLOAT and DOUBLE , correspond to Java's float and
double , which are 32-bit and 64-bit floating-point numbers.
The DECIMAL data type is used to represent arbitrary-precision decimals, like Java's
BigDecimal , and are commonly used for representing currency values. DECIMAL val-
ues are stored as unscaled integers. The precision is the number of digits in the unscaled
value, and the scale is the number of digits to the right of the decimal point. So, for ex-
ample, DECIMAL(5,2) stores numbers between −999.99 and 999.99. If the scale is
omitted then it defaults to 0, so DECIMAL(5) stores numbers in the range −99,999 to
99,999 (i.e., integers). If the precision is omitted then it defaults to 10, so DECIMAL is