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ALTER INDEX ... REBUILD builds an index that was created using the WITH DEFERRED REBUILD clause, or rebuilds a previously built index. If PARTITION is specified, only that partition is rebuilt.

Create/Drop Function

Temporary Functions

Create Temporary Function

CREATE TEMPORARY FUNCTION function_name AS class_name

This statement lets you create a function that is implemented by the class_name. You can use this function in Hive queries as long as the session lasts. You can use any class that is in the class path of Hive. You can add jars to class path by executing 'ADD FILESJAR' statements. Please refer to the CLI section Hive Interactive Shell Commands, including Hive Resources, for more information on how to add/delete files from the Hive classpath. Using this, you can register User Defined Functions (UDF's).

Also see Hive Plugins for general information about creating custom UDFs.

Drop Temporary Function

You can unregister a UDF as follows:

DROP TEMPORARY FUNCTION [IF EXISTS] function_name

In Hive 0.7.0 or later, DROP returns an error if the function doesn't exist, unless IF EXISTS is specified or the configuration variable hive.exec.drop.ignorenonexistent is set to true.

Permanent Functions

In Hive 0.13 or later, functions can be registered to the metastore, so they can be referenced in a query without having to create a temporary function each session.

Create Function

CREATE FUNCTION [db_name.]function_name AS class_name [USING JAR|FILE|ARCHIVE 'file_uri' [, JAR|FILE|ARCHIVE 'file_uri'] ]

This statement lets you create a function that is implemented by the class_name.  Jars, files, or archives which need to be added to the environment can be specified with the USING clause; when the function is referenced for the first time by a Hive session, these resources will be added to the environment as if ADD JAR/FILE had been issued.

The function will be added to the database specified, or to the current database at the time that the function was created. The function can be referenced by fully qualifying the function name (db_name.funciton_name), or can be referenced without qualification if the function is in the current database.

Drop Function

DROP FUNCTION [IF EXISTS] function_name

DROP returns an error if the function doesn't exist, unless IF EXISTS is specified or the configuration variable hive.exec.drop.ignorenonexistent is set to true.

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