Query using UDF query syntax - Amazon Athena
SynopsisParameters
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Query using UDF query syntax

The USING EXTERNAL FUNCTION clause specifies a UDF or multiple UDFs that can be referenced by a subsequent SELECT statement in the query. You need the method name for the UDF and the name of the Lambda function that hosts the UDF. In place of the Lambda function name, you can use the Lambda ARN. In cross-account scenarios, the Lambda ARN is required.

Synopsis

USING EXTERNAL FUNCTION UDF_name(variable1 data_type[, variable2 data_type][,...])
RETURNS data_type
LAMBDA 'lambda_function_name_or_ARN'
[, EXTERNAL FUNCTION UDF_name2(variable1 data_type[, variable2 data_type][,...]) 
RETURNS data_type 
LAMBDA 'lambda_function_name_or_ARN'[,...]]
SELECT  [...] UDF_name(expression) [, UDF_name2(expression)] [...]

Parameters

USING EXTERNAL FUNCTION UDF_name(variable1 data_type[, variable2 data_type][,...])

UDF_name specifies the name of the UDF, which must correspond to a Java method within the referenced Lambda function. Each variable data_type specifies a named variable and its corresponding data type that the UDF accepts as input. The data_type must be one of the supported Athena data types listed in the following table and map to the corresponding Java data type.

Athena data type Java data type

TIMESTAMP

java.time.LocalDateTime (UTC)

DATE

java.time.LocalDate (UTC)

TINYINT

java.lang.Byte

SMALLINT

java.lang.Short

REAL

java.lang.Float

DOUBLE

java.lang.Double

DECIMAL (see RETURNS note)

java.math.BigDecimal

BIGINT

java.lang.Long

INTEGER

java.lang.Int

VARCHAR

java.lang.String

VARBINARY

byte[]

BOOLEAN

java.lang.Boolean

ARRAY

java.util.List

ROW

java.util.Map<String, Object>
RETURNS data_type

data_type specifies the SQL data type that the UDF returns as output. Athena data types listed in the table above are supported. For the DECIMAL data type, use the syntax RETURNS DECIMAL(precision, scale) where precision and scale are integers.

LAMBDA 'lambda_function'

lambda_function specifies the name of the Lambda function to be invoked when running the UDF.

SELECT [...] UDF_name(expression) [...]

The SELECT query that passes values to the UDF and returns a result. UDF_name specifies the UDF to use, followed by an expression that is evaluated to pass values. Values that are passed and returned must match the corresponding data types specified for the UDF in the USING EXTERNAL FUNCTION clause.

Examples

For example queries based on the AthenaUDFHandler.java code on GitHub, see the GitHub Amazon Athena UDF connector page.