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17bc980d95
Documented the new TIMEZONE query option to set a time TIMEZONE to be used in timestamp conversions. Change-Id: I734b8b37ae2360422fce269ed87507a04e8c05ac Reviewed-on: http://gerrit.cloudera.org:8080/11505 Tested-by: Impala Public Jenkins <impala-public-jenkins@cloudera.com> Reviewed-by: Csaba Ringhofer <csringhofer@cloudera.com>
120 lines
3.5 KiB
XML
120 lines
3.5 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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http://www.apache.org/licenses/LICENSE-2.0
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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="3.1.0" id="timezone">
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<title>TIMEZONE Query Option (<keyword keyref="impala31_full"/> or higher only)</title>
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<titlealts audience="PDF">
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<navtitle>TIMEZONE</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="Querying"/>
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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>
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The <codeph>TIMEZONE</codeph> query option defines the timezone used for conversions
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between UTC and the local time. If not set, Impala uses the system time zone where the
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Coordinator Impalad runs. As query options are not sent to the Coordinator immediately,
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the timezones are validated only when the query runs.
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</p>
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<p>
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Impala takes the timezone into a consideration in the following cases:
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<ul>
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<li>
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When calling the <codeph>NOW()</codeph> function
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</li>
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<li>
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When converting between Unix time and timestamp if the
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<codeph>use_local_tz_for_unix_timestamp_conversions</codeph> flag is
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<codeph>TRUE</codeph>
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</li>
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<li>
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When reading Parquet timestamps written by Hive if the
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<codeph>convert_legacy_hive_parquet_utc_timestamps</codeph> flag is
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<codeph>TRUE</codeph>
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</li>
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</ul>
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</p>
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<p>
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<b>Syntax:</b>
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</p>
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<codeblock>SET TIMEZONE=<varname>time zone</varname></codeblock>
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<p>
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<varname>time zone</varname> can be a canonical code or a time zone name defined in
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<xref
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href="https://en.wikipedia.org/wiki/List_of_tz_database_time_zones"
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format="html" scope="external">IANA
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Time Zone Database</xref>. The value is case-sensitive.
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</p>
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<p>
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Leading/trailing quotes (') and double quotes (") are stripped.
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</p>
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<p>
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If <varname>time zone</varname> is an empty string, the time zone for the query is set to
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the default time zone of the Impalad Coordinator.
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</p>
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<p>
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If <varname>time zone</varname> is <codeph>NULL</codeph> or a space character, Impala
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returns an error when the query is executed.
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</p>
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<p>
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<b>Type:</b> String
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</p>
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<p>
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<b>Default:</b> The system time zone where the Coordinator Impalad runs
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</p>
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<p>
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<b>Examples:</b>
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<codeblock>SET TIMEZONE=UTC;
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SET TIMEZONE="Europe/Budapest";</codeblock>
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</p>
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<p>
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<b>Added in:</b> <keyword keyref="impala31"/>
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</p>
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</conbody>
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</concept>
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