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This patch adds documentation for AGG_MEM_CORRELATION_FACTOR and LARGE_AGG_MEM_THRESHOLD option introduced in Apache Impala 4.4.0. IMPALA-12548 fix behavior of AGG_MEM_CORRELATION_FACTOR. Higher value will lower memory estimation, while lower value will result in higher memory estimation. The documentation in ImpalaService.thrift, however, says the opposite. This patch fix documentation in thrift file as well. Testing: - Run "make plain-html" in docs/ dir and confirm the output. - Manually check with comments in PlannerTest.testAggNodeMaxMemEstimate() Change-Id: I00956a50fb7616ca3c3ea2fd75fd11239a6bcd90 Reviewed-on: http://gerrit.cloudera.org:8080/21793 Tested-by: Impala Public Jenkins <impala-public-jenkins@cloudera.com> Reviewed-by: Michael Smith <michael.smith@cloudera.com>
69 lines
2.5 KiB
XML
69 lines
2.5 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="large_agg_mem_threshold" rev="4.4.0">
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<title>LARGE_AGG_MEM_THRESHOLD Query Option (<keyword keyref="impala44"/> or higher only)</title>
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<titlealts audience="PDF">
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<navtitle>LARGE AGG MEM THRESHOLD</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="Performance"/>
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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 rev="4.4.0">
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<indexterm audience="hidden">LARGE_AGG_MEM_THRESHOLD query option</indexterm>
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The threshold for the query planner to determine whether memory estimation for an
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aggregation node is large or not. Together with <codeph>AGG_MEM_CORRELATION_FACTOR</codeph>,
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the planner will use this value to lower memory estimation for a large aggregation node.
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</p>
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<p>
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Users can set this option value to 0.0 so the planner stays using the default
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NDV multiplication based-estimation. See <codeph>AGG_MEM_CORRELATION_FACTOR</codeph>
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documentation for more detail.
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</p>
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<p conref="../shared/impala_common.xml#common/type_integer"/>
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<p conref="../shared/impala_common.xml#common/default_blurb"/>
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<p>
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<codeph>536870912</codeph> (512 MB)
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</p>
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<p conref="../shared/impala_common.xml#common/units_blurb"/>
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<p conref="../shared/impala_common.xml#common/added_in_440"/>
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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_agg_mem_correlation_factor.xml"/>
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</p>
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</conbody>
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</concept>
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