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eadd35f6d5
The recent documentation formatting changes introduced the navigation panel on the left. However, due to the length of the query options navigation title these could overlap with the documentation paragraphs. This commit removes the underscores from the navigation titles of the query options, so browsers can break them into multiple lines. Additionally, the "SET" and "Query Options for the SET Statement" pages are merged to save some more space for the query option navigation titles. Testing: - Built the documentation and tested manually Change-Id: Icec787d7a2af848aaaff65be2ecf311a5ce8fe7f Reviewed-on: http://gerrit.cloudera.org:8080/20556 Tested-by: Impala Public Jenkins <impala-public-jenkins@cloudera.com> Reviewed-by: Jason Fehr <jfehr@cloudera.com> Reviewed-by: Peter Rozsa <prozsa@cloudera.com> Reviewed-by: Tamas Mate <tmater@apache.org>
87 lines
4.4 KiB
XML
87 lines
4.4 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="2.3.0" id="live_summary">
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<title>LIVE_SUMMARY Query Option (<keyword keyref="impala23"/> or higher only)</title>
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<titlealts audience="PDF"><navtitle>LIVE SUMMARY</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="Impala Query Options"/>
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<data name="Category" value="Querying"/>
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<data name="Category" value="Performance"/>
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<data name="Category" value="Reports"/>
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<data name="Category" value="impala-shell"/>
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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="2.3.0"> When the <codeph>LIVE_SUMMARY</codeph> query option is set
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to <codeph>TRUE</codeph>, Impala displays the same output as the
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<codeph>SUMMARY</codeph> command for queries submitted through the
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<cmdname>impala-shell</cmdname> command, with the measurements updated
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in real time as the query progresses. When the query finishes, the final
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<codeph>SUMMARY</codeph> output remains visible in the
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<cmdname>impala-shell</cmdname> console output. </p>
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<p>Starting in <keyword keyref="impala31"/>, the summary output also
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includes the queuing status consisting of whether the query was queued and
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what was the latest queuing reason.</p>
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<p><b>Type:</b>
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<codeph>Boolean</codeph></p>
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<p><b>Default:</b>
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<codeph>FALSE (0)</codeph></p>
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<p conref="../shared/impala_common.xml#common/command_line_blurb"/>
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<p> You can enable this query option within <cmdname>impala-shell</cmdname>
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by starting the shell with the <codeph>--live_summary</codeph>
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command-line option. You can still turn this setting off and on again
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within the shell through the <codeph>SET</codeph> command. </p>
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<p conref="../shared/impala_common.xml#common/usage_notes_blurb"/>
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<p> The live summary output can be useful for evaluating long-running
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queries, to evaluate which phase of execution takes up the most time, or
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if some hosts take much longer than others for certain operations,
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dragging overall performance down. By making the information available in
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real time, this feature lets you decide what action to take even before
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you cancel a query that is taking much longer than normal. </p>
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<p> For example, you might see the HDFS scan phase taking a long time, and
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therefore revisit performance-related aspects of your schema design such
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as constructing a partitioned table, switching to the Parquet file format,
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running the <codeph>COMPUTE STATS</codeph> statement for the table, and so
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on. Or you might see a wide variation between the average and maximum
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times for all hosts to perform some phase of the query, and therefore
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investigate if one particular host needed more memory or was experiencing
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a network problem. </p>
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<p conref="../shared/impala_common.xml#common/live_reporting_details"/>
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<p> For a simple and concise way of tracking the progress of an interactive
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query, see <xref href="impala_live_progress.xml#live_progress"/>. </p>
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<p conref="../shared/impala_common.xml#common/restrictions_blurb"/>
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<p
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conref="../shared/impala_common.xml#common/impala_shell_progress_reports_compute_stats_caveat"/>
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<p
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conref="../shared/impala_common.xml#common/impala_shell_progress_reports_shell_only_caveat"/>
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<p conref="../shared/impala_common.xml#common/added_in_230"/>
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<p
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conref="../shared/impala_common.xml#common/live_progress_live_summary_asciinema"
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/>
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</conbody>
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</concept>
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