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18927ac852
Genericize 3-part version numbers in "known issues". Genericize CDH version numbers in 'ports' topic. Genericize 'Cloudera' and hostnames in 'Tables' topic. Genericize the version numbers in 'added in' blurbs. Remove lots of CDH / Impala notices from release notes. Remove obsolete conref'able elements that weren't actually being called from anywhere, that contained CDH version number wording. Reword 'Cloudera recommends'. Remove more hidden or commented material with Cloudera-specific wording. Remove obsolete CDH references from 'incompatible changes'. Change 'cloudera' HDFS username for LOAD DATA examples. Remove material related to big lists of CDH fixed JIRAs. Genericize some CDH-related language. Change-Id: Iaa5db6c20f4d010972ade4945a3ea59b32ef95de Reviewed-on: http://gerrit.cloudera.org:8080/6267 Reviewed-by: Ambreen Kazi <ambreen.kazi@cloudera.com> Reviewed-by: John Russell <jrussell@cloudera.com> Tested-by: Impala Public Jenkins
146 lines
6.3 KiB
XML
146 lines
6.3 KiB
XML
<?xml version="1.0" encoding="UTF-8"?>
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<!--
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Licensed to the Apache Software Foundation (ASF) under one
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or more contributor license agreements. See the NOTICE file
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distributed with this work for additional information
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regarding copyright ownership. The ASF licenses this file
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to you under the Apache License, Version 2.0 (the
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"License"); you may not use this file except in compliance
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with the License. You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing,
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software distributed under the License is distributed on an
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"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
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KIND, either express or implied. See the License for the
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specific language governing permissions and limitations
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under the License.
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-->
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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="hidden">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">
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<p rev="2.5.0 IMPALA-2843">
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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">
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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="">
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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">
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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">
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create function my_func location '/user/impala/udfs/udf-examples.jar'
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symbol='org.apache.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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