This is the documentation for Cloudera Impala 1.4.0.
Documentation for other versions is available at Cloudera.com.

DOUBLE Data Type

An 8-byte (double precision) floating-point data type used in CREATE TABLE and ALTER TABLE statements.

Range: 4.94065645841246544e-324d .. 1.79769313486231570e+308, positive or negative

Conversions: Impala does not automatically convert DOUBLE to any other type. You can use CAST() to convert DOUBLE values to FLOAT, TINYINT, SMALLINT, INT, BIGINT, STRING, TIMESTAMP, or BOOLEAN. You can use exponential notation in DOUBLE literals or when casting from STRING, for example 1.0e6 to represent one million.

The data type REAL is an alias for DOUBLE.

Examples:

CREATE TABLE t1 (x DOUBLE);
SELECT CAST(1000.5 AS DOUBLE);

Related information: Literals, Mathematical Functions