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8377b9949c
For this change to land in master, the audience="hidden" code review needs to be completed first. Otherwise, the doc build would still work but the audience="hidden" content would be visible rather than hidden as desired. Some work happening in parallel might introduce additional instances of audience="Cloudera". I suggest addressing those in a followup CR so this global change can land quickly. Since the changes apply across so many different files, but are so narrow in scope, I suggest that the way to validate (check that no extraneous changes were introduced accidentally) is to diff just the changed lines: git diff -U0 HEAD^ HEAD In patch set 2, I updated other topics marked audience="Cloudera" by CRs that were pushed in the meantime. Change-Id: Ic93d89da77e1f51bbf548a522d98d0c4e2fb31c8 Reviewed-on: http://gerrit.cloudera.org:8080/5613 Reviewed-by: John Russell <jrussell@cloudera.com> Tested-by: Impala Public Jenkins
79 lines
2.7 KiB
XML
79 lines
2.7 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="num_nodes">
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<title>NUM_NODES Query Option</title>
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<titlealts audience="PDF"><navtitle>NUM_NODES</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="Developers"/>
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<data name="Category" value="Data Analysts"/>
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<data name="Category" value="Troubleshooting"/>
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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">NUM_NODES query option</indexterm>
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Limit the number of nodes that process a query, typically during debugging.
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</p>
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<p>
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<b>Type:</b> numeric
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</p>
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<p>
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<b>Allowed values:</b> Only accepts the values 0
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(meaning all nodes) or 1 (meaning all work is done on the coordinator node).
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</p>
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<p>
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<b>Default:</b> 0
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</p>
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<p conref="../shared/impala_common.xml#common/usage_notes_blurb"/>
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<p>
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If you are diagnosing a problem that you suspect is due to a timing issue due to
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distributed query processing, you can set <codeph>NUM_NODES=1</codeph> to verify
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if the problem still occurs when all the work is done on a single node.
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</p>
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<p conref="../shared/impala_common.xml#common/num_nodes_tip"/>
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<note type="warning" rev="DOCS-1161">
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<p>
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Because this option results in increased resource utilization on a single host,
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it could cause problems due to contention with other Impala statements or
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high resource usage. Symptoms could include queries running slowly, exceeding the memory limit,
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or appearing to hang. Use it only in a single-user development/test environment;
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<b>do not</b> use it in a production environment or in a cluster with a high-concurrency
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or high-volume or performance-critical workload.
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</p>
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</note>
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</conbody>
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</concept>
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