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d484d2f684
This now gives a clean RAT check with bin/check-rat-report.py, which is one way for the Impala community to check compliance with ASF rules on intellectual property. Change-Id: I2ad06435f84a65ba126759e42a18fdaf52cd7036 Reviewed-on: http://gerrit.cloudera.org:8080/5232 Reviewed-by: Jim Apple <jbapple-impala@apache.org> Tested-by: Impala Public Jenkins Reviewed-by: John Russell <jrussell@cloudera.com>
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="Cloudera" 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="Cloudera">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 CDH 5.2 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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