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2280c1362e
Document the feature introduced in IMPALA-12345. Add a few more tests to the QuotaExamples test which demonstrate the examples used in the docs. Clarify in docs and code the behavior when a user is a member of more than one group for which there are rules. In this case the least restrictive rule applies. Also document the '--max_hs2_sessions_per_user' flag introduced in IMPALA-12264. Change-Id: I82e044adb072a463a1e4f74da71c8d7d48292970 Reviewed-on: http://gerrit.cloudera.org:8080/22100 Reviewed-by: Impala Public Jenkins <impala-public-jenkins@cloudera.com> Tested-by: Impala Public Jenkins <impala-public-jenkins@cloudera.com>
344 lines
9.8 KiB
XML
344 lines
9.8 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="intro_client">
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<title>Impala Client Access</title>
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<titlealts audience="PDF">
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<navtitle>Client Access</navtitle>
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</titlealts>
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<conbody>
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<p>
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Application developers have a number of options to interface with Impala. The core
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development language with Impala is SQL. You can also use Java or other languages to
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interact with Impala through the standard JDBC and ODBC interfaces used by many business
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intelligence tools. For specialized kinds of analysis, you can supplement the Impala
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built-in functions by writing user-defined functions in C++ or Java.
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</p>
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<p>
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You can connect and submit requests to the Impala through:
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</p>
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<ul>
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<li>
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The impala-shell interactive command interpreter
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</li>
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<li>
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The Hue web-based user interface
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</li>
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<li>
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JDBC
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</li>
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<li>
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ODBC
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</li>
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</ul>
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<p>
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Impala clients can connect to the Coordinator Impala Daemon (<codeph>impalad</codeph>) via
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HiveServer2 over HTTP or over the TCP binary. Both HTTP and binary support the Kerberos
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SPNEGO and LDAP for authentication to Impala. See below for the default ports and the
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Impala flags to change the ports.
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</p>
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<p>
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<simpletable frame="all" relcolwidth="1.0* 1.03* 2.38*"
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id="simpletable_tr2_gnt_43b">
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<strow>
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<stentry><b>Protocol</b>
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</stentry>
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<stentry><b>Default Port</b>
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</stentry>
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<stentry><b>Flag to Specify an Alternate Port</b>
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</stentry>
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</strow>
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<strow>
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<stentry>HTTP</stentry>
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<stentry>28000</stentry>
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<stentry><codeph>‑‑hs2_http_port</codeph>
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</stentry>
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</strow>
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<strow>
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<stentry>Binary TCP</stentry>
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<stentry>21050</stentry>
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<stentry><codeph>‑‑hs2_port</codeph>
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</stentry>
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</strow>
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</simpletable>
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</p>
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<p>
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Each <codeph>impalad</codeph> daemon process, running on separate nodes in a cluster,
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listens to <xref href="impala_ports.xml#ports">several ports</xref> for incoming requests:
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</p>
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<ul>
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<li>
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Requests from <codeph>impala-shell</codeph> and Hue are routed to the
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<codeph>impalad</codeph> daemons through the same port.
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</li>
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<li>
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The <codeph>impalad</codeph> daemons listen on separate ports for JDBC and ODBC
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requests.
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</li>
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</ul>
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<section id="section_egg_wjt_f3b">
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<title>Impala Startup Options for Client Connections</title>
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<p>
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Use the following flags when starting Impala Daemon coordinator to control client
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connections to Impala.
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</p>
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<dl>
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<dlentry>
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<dt>
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--accepted_client_cnxn_timeout
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</dt>
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<dd>
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Controls how Impala treats new connection requests if it has run out of the number
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of threads configured by <codeph>--fe_service_threads</codeph>.
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<p>
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If <codeph>--accepted_client_cnxn_timeout > 0</codeph>, new connection requests
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are rejected if Impala can't get a server thread within the specified (in seconds)
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timeout.
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</p>
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<p>
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If <codeph>--accepted_client_cnxn_timeout=0</codeph>, i.e. no timeout, clients
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wait indefinitely to open the new session until more threads are available.
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</p>
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<p>
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The default timeout is 5 minutes.
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</p>
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<p>
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The timeout applies only to client facing thrift servers, i.e., HS2 and Beeswax
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servers.
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</p>
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</dd>
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</dlentry>
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<dlentry>
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<dt>
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--disconnected_session_timeout
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</dt>
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<dd>
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When a HiveServer2 session has had no open connections for longer than this value,
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the session will be closed, and any associated queries will be unregistered.
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<p>
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Specify the value in hours.
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</p>
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<p>
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The default value is 1 hour.
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</p>
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<p>
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This flag does not apply to Beeswax clients. When a Beeswax client connection is
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closed, Impala closes the session associated with that connection.
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</p>
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</dd>
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</dlentry>
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<dlentry>
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<dt>
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--fe_service_threads
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</dt>
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<dd>
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Specifies the maximum number of concurrent client connections allowed. The default
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value is 64 with which 64 queries can run simultaneously.
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<p>
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If you have more clients trying to connect to Impala than the value of this
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setting, the later arriving clients have to wait for the duration specified by
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<codeph>--accepted_client_cnxn_timeout</codeph>. You can increase this value to
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allow more client connections. However, a large value means more threads to be
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maintained even if most of the connections are idle, and it could negatively
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impact query latency. Client applications should use the connection pool to avoid
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need for large number of sessions.
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</p>
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</dd>
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</dlentry>
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<dlentry>
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<dt>
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--hs2_http_port
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</dt>
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<dd>
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Specifies the port for clients to connect to Impala server over HTTP.
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<p>
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The default port is 28000.
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</p>
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<p>
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You can disable the HTTP end point for clients by setting the flag to
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<codeph>0</codeph>.
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</p>
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<p>
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To enable TLS/SSL for HiveServer2 HTTP endpoint use
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<codeph>--ssl_server_certificate</codeph> and <codeph>--ssl_private_key</codeph>.
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See <xref
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href="impala_ssl.xml#ssl"/> for detail.
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</p>
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</dd>
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</dlentry>
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<dlentry>
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<dt>
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--idle_client_poll_period_s
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</dt>
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<dd>
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The value of this setting specifies how frequently Impala polls to check if a client
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connection is idle and closes it if the connection is idle. A client connection is
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idle if all sessions associated with the client connection are idle.
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<p>
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By default, <codeph>--idle_client_poll_period_s</codeph> is set to 30 seconds.
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</p>
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<p>
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If <codeph>--idle_client_poll_period_s</codeph> is set to 0, idle client connections
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stay open until explicitly closed by the clients.
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</p>
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<p>
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The connection will only be closed if all the associated sessions are idle or
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closed. Sessions cannot be idle unless either the flag
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<codeph>--idle_session_timeout</codeph> or the
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<codeph>IDLE_SESSION_TIMEOUT</codeph> query option is set to greater than 0. If
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idle session timeout is not configured, a session cannot become idle by
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definition, and therefore its connection stays open until the client explicitly
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closes it.
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</p>
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</dd>
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</dlentry>
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<dlentry>
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<dt>
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--max_cookie_lifetime_s
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</dt>
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<dd>
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Starting in Impala 3.4.0, Impala uses cookies for authentication when clients
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connect via HiveServer2 over HTTP. Use the <codeph>--max_cookie_lifetime_s</codeph>
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startup flag to control how long generated cookies are valid for.
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<p>
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Specify the value in seconds.
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</p>
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<p>
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The default value is 1 day.
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</p>
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<p>
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Setting the flag to <codeph>0</codeph> disables cookie support.
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</p>
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<p>
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When an unexpired cookie is successfully verified, the user name contained in the
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cookie is set on the connection.
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</p>
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<p>
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Each <codeph>impalad</codeph> uses its own key to generate the signature, so
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clients that reconnect to a different <codeph>impalad</codeph> have to
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re-authenticate.
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</p>
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<p>
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On a single <codeph>impalad</codeph>, cookies are valid across sessions and
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connections.
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</p>
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</dd>
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</dlentry>
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<dlentry>
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<dt>
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--max_hs2_sessions_per_user
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</dt>
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<dd>
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Specifies the maximum allowed number of HiveServer2 sessions that can be
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opened by any single connected user on a coordinator.
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<p>
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The default is -1. Setting to -1 or 0 disables this feature.
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</p>
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</dd>
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</dlentry>
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</dl>
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</section>
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</conbody>
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</concept>
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