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Change-Id: Ic10fd66d8a83d10c0900e93a00241d532902a759 Reviewed-on: http://gerrit.cloudera.org:8080/12496 Tested-by: Impala Public Jenkins <impala-public-jenkins@cloudera.com> Reviewed-by: Alex Rodoni <arodoni@cloudera.com>
83 lines
2.6 KiB
XML
83 lines
2.6 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 id="disable_codegen">
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<title>DISABLE_CODEGEN Query Option</title>
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<titlealts audience="PDF">
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<navtitle>DISABLE_CODEGEN</navtitle>
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</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="Impala Query Options"/>
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<data name="Category" value="Troubleshooting"/>
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<data name="Category" value="Performance"/>
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</metadata>
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</prolog>
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<conbody>
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<p>
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The <codeph>DISABLE_CODEGEN</codeph> is a debug option, and it's used to work around any
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issues with Impala's runtime code generation. If a query fails with an <q>illegal
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instruction</q> or other hardware-specific message, try setting
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<codeph>DISABLE_CODEGEN=true</codeph> and running the query again. If the query succeeds
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only when the <codeph>DISABLE_CODEGEN</codeph> option is turned on, submit the problem to
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<keyword keyref="support_org"> </keyword> and include that detail in the problem report.
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</p>
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<p>
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Most queries will run significantly slower with <codeph>DISABLE_CODEGEN=true</codeph>.
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</p>
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<p>
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In Impala 2.10 and higher, the <codeph>DISABLE_CODEGEN_ROWS_THRESHOLD</codeph>
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optimisation automatically disables codegen for small queries because short-running
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queries may run faster without the overhead of codegen.
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</p>
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<p>
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The following values are supported:
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<ul>
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<li>
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<codeph>TRUE</codeph> or <codeph>1</codeph>: Disables codegen.
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</li>
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<li>
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<codeph>FALSE</codeph> or <codeph>0</codeph>: Enables codegen.
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</li>
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</ul>
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</p>
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<p>
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<b>Type:</b> Boolean
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</p>
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<p conref="../shared/impala_common.xml#common/default_false_0"/>
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</conbody>
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</concept>
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