DROP FUNCTION Statement

DROP FUNCTION Statement DROP FUNCTION

DROP FUNCTION statement Removes a user-defined function (UDF), so that it is not available for execution during Impala SELECT or INSERT operations.

To drop C++ UDFs and UDAs:

DROP [AGGREGATE] FUNCTION [IF EXISTS] [db_name.]function_name(type[, type...])

The preceding syntax, which includes the function signature, also applies to Java UDFs that were created using the corresponding CREATE FUNCTION syntax that includes the argument and return types. After upgrading to or higher, consider re-creating all Java UDFs with the CREATE FUNCTION syntax that does not include the function signature. Java UDFs created this way are now persisted in the metastore database and do not need to be re-created after an Impala restart.

To drop Java UDFs (created using the CREATE FUNCTION syntax with no function signature):

DROP FUNCTION [IF EXISTS] [db_name.]function_name

Because the same function name could be overloaded with different argument signatures, you specify the argument types to identify the exact function to drop.

The user ID that the impalad daemon runs under, typically the impala user, does not need any particular HDFS permissions to perform this statement. All read and write operations are on the metastore database, not HDFS files and directories.

The following example shows how to drop Java functions created with the signatureless CREATE FUNCTION syntax in and higher. Issuing DROP FUNCTION function_name removes all the overloaded functions under that name. (See for a longer example showing how to set up such functions in the first place.)