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These are refugees from doc_prototype. They can be rendered with the DITA Open Toolkit version 2.3.3 by: /tmp/dita-ot-2.3.3/bin/dita \ -i impala.ditamap \ -f html5 \ -o $(mktemp -d) \ -filter impala_html.ditaval Change-Id: I8861e99adc446f659a04463ca78c79200669484f Reviewed-on: http://gerrit.cloudera.org:8080/5014 Reviewed-by: John Russell <jrussell@cloudera.com> Tested-by: John Russell <jrussell@cloudera.com>
128 lines
5.6 KiB
XML
128 lines
5.6 KiB
XML
<?xml version="1.0" encoding="UTF-8"?>
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<!DOCTYPE concept PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd">
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<concept rev="1.2" id="drop_function">
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<title>DROP FUNCTION Statement</title>
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<titlealts audience="PDF"><navtitle>DROP FUNCTION</navtitle></titlealts>
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<prolog>
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<metadata>
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<data name="Category" value="Impala"/>
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<data name="Category" value="SQL"/>
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<data name="Category" value="DDL"/>
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<data name="Category" value="Impala Functions"/>
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<data name="Category" value="UDFs"/>
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<data name="Category" value="Schemas"/>
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<data name="Category" value="Developers"/>
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<data name="Category" value="Data Analysts"/>
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</metadata>
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</prolog>
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<conbody>
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<p>
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<indexterm audience="Cloudera">DROP FUNCTION statement</indexterm>
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Removes a user-defined function (UDF), so that it is not available for execution during Impala
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<codeph>SELECT</codeph> or <codeph>INSERT</codeph> operations.
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</p>
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<p conref="../shared/impala_common.xml#common/syntax_blurb"/>
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<p>
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To drop C++ UDFs and UDAs:
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</p>
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<codeblock>DROP [AGGREGATE] FUNCTION [IF EXISTS] [<varname>db_name</varname>.]<varname>function_name</varname>(<varname>type</varname>[, <varname>type</varname>...])</codeblock>
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<note rev="2.5.0 IMPALA-2843 CDH-39148">
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<p rev="2.5.0 IMPALA-2843 CDH-39148">
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The preceding syntax, which includes the function signature, also applies to Java UDFs that were created
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using the corresponding <codeph>CREATE FUNCTION</codeph> syntax that includes the argument and return types.
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After upgrading to <keyword keyref="impala25_full"/> or higher, consider re-creating all Java UDFs with the
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<codeph>CREATE FUNCTION</codeph> syntax that does not include the function signature. Java UDFs created this
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way are now persisted in the metastore database and do not need to be re-created after an Impala restart.
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</p>
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</note>
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<p rev="2.5.0 IMPALA-2843 CDH-39148">
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To drop Java UDFs (created using the <codeph>CREATE FUNCTION</codeph> syntax with no function signature):
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</p>
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<codeblock rev="2.5.0">DROP FUNCTION [IF EXISTS] [<varname>db_name</varname>.]<varname>function_name</varname></codeblock>
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<!--
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Examples:
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CREATE FUNCTION IF NOT EXISTS foo location '/path/to/jar' SYMBOL='TestUdf';
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CREATE FUNCTION bar location '/path/to/jar' SYMBOL='TestUdf2';
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DROP FUNCTION foo;
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DROP FUNCTION IF EXISTS bar;
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-->
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<p conref="../shared/impala_common.xml#common/ddl_blurb"/>
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<p conref="../shared/impala_common.xml#common/usage_notes_blurb"/>
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<p>
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Because the same function name could be overloaded with different argument signatures, you specify the
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argument types to identify the exact function to drop.
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</p>
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<p conref="../shared/impala_common.xml#common/restrictions_blurb"/>
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<p conref="../shared/impala_common.xml#common/udf_persistence_restriction"/>
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<p conref="../shared/impala_common.xml#common/cancel_blurb_no"/>
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<p conref="../shared/impala_common.xml#common/permissions_blurb"/>
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<p rev="CDH-19187">
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The user ID that the <cmdname>impalad</cmdname> daemon runs under,
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typically the <codeph>impala</codeph> user, does not need any
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particular HDFS permissions to perform this statement.
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All read and write operations are on the metastore database,
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not HDFS files and directories.
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</p>
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<p conref="../shared/impala_common.xml#common/example_blurb"/>
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<p rev="2.5.0 IMPALA-2843 CDH-39148">
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The following example shows how to drop Java functions created with the signatureless
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<codeph>CREATE FUNCTION</codeph> syntax in <keyword keyref="impala25_full"/> and higher.
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Issuing <codeph>DROP FUNCTION <varname>function_name</varname></codeph> removes all the
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overloaded functions under that name.
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(See <xref href="impala_create_function.xml#create_function"/> for a longer example
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showing how to set up such functions in the first place.)
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</p>
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<codeblock rev="2.5.0 IMPALA-2843 CDH-39148">
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create function my_func location '/user/impala/udfs/udf-examples-cdh570.jar'
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symbol='com.cloudera.impala.TestUdf';
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show functions;
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+-------------+---------------------------------------+-------------+---------------+
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| return type | signature | binary type | is persistent |
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+-------------+---------------------------------------+-------------+---------------+
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| BIGINT | my_func(BIGINT) | JAVA | true |
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| BOOLEAN | my_func(BOOLEAN) | JAVA | true |
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| BOOLEAN | my_func(BOOLEAN, BOOLEAN) | JAVA | true |
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...
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| BIGINT | testudf(BIGINT) | JAVA | true |
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| BOOLEAN | testudf(BOOLEAN) | JAVA | true |
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| BOOLEAN | testudf(BOOLEAN, BOOLEAN) | JAVA | true |
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...
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drop function my_func;
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show functions;
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+-------------+---------------------------------------+-------------+---------------+
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| return type | signature | binary type | is persistent |
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+-------------+---------------------------------------+-------------+---------------+
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| BIGINT | testudf(BIGINT) | JAVA | true |
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| BOOLEAN | testudf(BOOLEAN) | JAVA | true |
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| BOOLEAN | testudf(BOOLEAN, BOOLEAN) | JAVA | true |
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...
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</codeblock>
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<p conref="../shared/impala_common.xml#common/related_info"/>
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<p>
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<xref href="impala_udf.xml#udfs"/>, <xref href="impala_create_function.xml#create_function"/>
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</p>
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</conbody>
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</concept>
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