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ff5d1ceb0d
A number of 'CDH' by itself were turned into substitution variables resolving to 'Apache Hadoop'. Also fixed some stray instances of CDH version numbers. In some cases, 'CDH' or 'CDH 5' by itself was superfluous and was just removed. Change-Id: I979ea73ccaa5873d4108545f18f598072fb5e05f Reviewed-on: http://gerrit.cloudera.org:8080/6352 Reviewed-by: John Russell <jrussell@cloudera.com> Tested-by: Impala Public Jenkins
123 lines
4.2 KiB
XML
123 lines
4.2 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 audience="hidden" id="date" rev="2.0.0">
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<title>DATE Data Type (<keyword keyref="impala21"/> or higher only)</title>
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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 Data Types"/>
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<data name="Category" value="SQL"/>
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<data name="Category" value="Data Analysts"/>
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<data name="Category" value="Developers"/>
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<data name="Category" value="Dates and Times"/>
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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">DATE data type</indexterm>
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A type representing the date (year, month, and day) as a single numeric value. Used to represent a broader
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date range than possible with the <codeph>TIMESTAMP</codeph> type, with fewer distinct values than
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<codeph>TIMESTAMP</codeph>, and in a more compact and efficient form than using a <codeph>STRING</codeph>
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such as <codeph>'2014-12-31'</codeph>.
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</p>
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<p conref="../shared/impala_common.xml#common/syntax_blurb"/>
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<codeblock><varname>column_name</varname> DATE</codeblock>
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<p>
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<b>Range:</b> January 1, -4712 BC .. December 31, 9999 AD.
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</p>
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<p conref="../shared/impala_common.xml#common/hbase_ok"/>
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<p conref="../shared/impala_common.xml#common/parquet_blurb"/>
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<ul>
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<li>
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This type can be read from and written to Parquet files.
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</li>
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<li>
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There is no requirement for a particular level of Parquet.
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</li>
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<li>
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Parquet files generated by Impala and containing this type can be freely interchanged with other components
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such as Hive and MapReduce.
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</li>
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</ul>
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<p conref="../shared/impala_common.xml#common/hive_blurb"/>
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<p>
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TK.
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</p>
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<p conref="../shared/impala_common.xml#common/conversion_blurb"/>
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<p>
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TK.
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</p>
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<p conref="../shared/impala_common.xml#common/partitioning_blurb"/>
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<p>
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This type can be used for partition key columns. Because it has less granularity (and thus fewer distinct
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values) than an equivalent <codeph>TIMESTAMP</codeph> column, and numeric columns are more efficient as
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partition keys than strings, prefer to partition by a <codeph>DATE</codeph> column rather than a
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<codeph>TIMESTAMP</codeph> column or a <codeph>STRING</codeph> representation of a date.
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</p>
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<p conref="../shared/impala_common.xml#common/compatibility_blurb"/>
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<p>
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This type is available on <keyword keyref="impala20_full"/> or higher.
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</p>
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<p conref="../shared/impala_common.xml#common/internals_2_bytes"/>
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<p conref="../shared/impala_common.xml#common/added_in_20"/>
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<p conref="../shared/impala_common.xml#common/column_stats_constant"/>
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<p conref="../shared/impala_common.xml#common/restrictions_blurb"/>
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<p>
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Things happen when converting <codeph>TIMESTAMP</codeph> to <codeph>DATE</codeph> or <codeph>DATE</codeph> to
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<codeph>TIMESTAMP</codeph>. TK.
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</p>
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<p conref="../shared/impala_common.xml#common/example_blurb"/>
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<p conref="../shared/impala_common.xml#common/related_info"/>
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<p>
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The <xref href="impala_timestamp.xml#timestamp">TIMESTAMP</xref> data type is closely related. Some functions
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from <xref href="impala_datetime_functions.xml#datetime_functions"/> accept and return <codeph>DATE</codeph>
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values.
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</p>
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</conbody>
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</concept>
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