releases/1.6.0/docs/release_notes.html - kudu - Git at Google

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 title: Apache Kudu 1.6.0 Release Notes
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 <div class="container">
   <div class="row">
     <div class="col-md-9">

 <h1>Apache Kudu 1.6.0 Release Notes</h1>
       <div class="sect1">
 <h2 id="rn_1.6.0_upgrade_notes"><a class="link" href="#rn_1.6.0_upgrade_notes">Upgrade Notes</a></h2>
 <div class="sectionbody">
 <div class="ulist">
 <ul>
 <li>
 <p>Upgrading directly from Kudu 1.5.0 is supported and no special upgrade steps
 are required. A rolling upgrade may work, however it has not been tested.
 When upgrading Kudu, it is recommended to first shut down all Kudu processes
 across the cluster, then upgrade the software on all servers, then restart
 the Kudu processes on all servers in the cluster.</p>
 </li>
 </ul>
 </div>
 </div>
 </div>
 <div class="sect1">
 <h2 id="rn_1.6.0_obsoletions"><a class="link" href="#rn_1.6.0_obsoletions">Obsoletions</a></h2>
 <div class="sectionbody">
 <div class="ulist">
 <ul>
 <li>
 <p>Support for Spark 1 (kudu-spark_2.10) has been <strong>removed</strong> in Kudu 1.6.0 and
 now only Spark 2 is supported. Spark 1 support was deprecated in Kudu 1.5.0.</p>
 </li>
 </ul>
 </div>
 </div>
 </div>
 <div class="sect1">
 <h2 id="rn_1.6.0_deprecations"><a class="link" href="#rn_1.6.0_deprecations">Deprecations</a></h2>
 <div class="sectionbody">
 <div class="ulist">
 <ul>
 <li>
 <p>Support for Java 7 has been deprecated since Kudu 1.5.0 and may be removed in
 the next major release.</p>
 </li>
 </ul>
 </div>
 </div>
 </div>
 <div class="sect1">
 <h2 id="rn_1.6.0_new_features"><a class="link" href="#rn_1.6.0_new_features">New features</a></h2>
 <div class="sectionbody">
 <div class="ulist">
 <ul>
 <li>
 <p>Tablet servers' tolerance of disk failures is now enabled by default and has
 been extended to handle data directory failures at runtime. In the event of
 a disk failure at runtime, any tablets with data on a failed disk will be
 shut down and restarted on another tablet server. There is a configurable
 tradeoff between a newly added tablet&#8217;s tolerance to disk failures and its
 ability to parallelize reads via the experimental
 <code>--fs_target_data_dirs_per_tablet</code> flag. Tablets that are spread across fewer
 disks are less likely to be affected by a disk failure, at the cost of
 reduced parallelism. By default, tablets are striped across all available
 disks. Note that the first configured data directory and the WAL directory
 cannot currently tolerate disk failures. This will be further improved in
 future Kudu releases.</p>
 </li>
 <li>
 <p>Kudu servers can now adopt new data directories via the new
 <code>kudu fs update_dirs</code> tool. The new directory will be used by new tablet
 replicas only. Note that removing directories is not yet supported
 (see <a href="https://issues.apache.org/jira/browse/KUDU-2202">KUDU-2202</a>).</p>
 </li>
 <li>
 <p>Kudu servers have two new flags to control webui TLS/HTTPS
 settings: <code>--webserver_tls_ciphers</code> and <code>--webserver_tls_min_protocol</code>.
 These flags allow the advertised TLS ciphers and TLS protocol versions to be
 configured. Additionally, the webserver now excludes insecure legacy ciphers
 by default
 (see <a href="https://issues.apache.org/jira/browse/KUDU-2190">KUDU-2190</a>).</p>
 </li>
 </ul>
 </div>
 </div>
 </div>
 <div class="sect1">
 <h2 id="_optimizations_and_improvements"><a class="link" href="#_optimizations_and_improvements">Optimizations and improvements</a></h2>
 <div class="sectionbody">
 <div class="ulist">
 <ul>
 <li>
 <p>Kudu servers can now tolerate short interruptions in NTP clock
 synchronization. NTP synchronization is still required when any Kudu daemon
 starts up. If NTP synchronization is not available, diagnostic information
 is now logged to help pinpoint the issue
 (see <a href="https://issues.apache.org/jira/browse/KUDU-1578">KUDU-1578</a>).</p>
 </li>
 <li>
 <p>Tablet server startup time has been improved significantly on servers
 containing large numbers of blocks.</p>
 </li>
 <li>
 <p>The log block manager now performs disk data deletion in batches. This
 optimization can significantly reduce the time taken to delete data on a tablet.</p>
 </li>
 <li>
 <p>The usage of sensitive data redaction flag has been slightly changed. By
 setting <code>--redact=log</code> flag, redaction will be disabled in the web UI but
 retained for server logs. Alternatively, <code>--redact=none</code> can be used to
 disable redaction completely.</p>
 </li>
 <li>
 <p>The Spark DataSource integration now can take advantage of scan locality
 for better scan performance, the scan will take place at the closest replica
 instead of going to the leader.</p>
 </li>
 <li>
 <p>Various optimizations were made to reduce the 99th percentile latency of
 writes on the tablet server. This can also improve throughput on certain
 write workloads, particularly on larger clusters.</p>
 </li>
 <li>
 <p>Kudu may now be configured to ignore system-wide auth_to_local mappings
 configured in /etc/krb5.conf by setting the configuration flag
 <code>--use_system_auth_to_local=false</code>
 (see <a href="https://issues.apache.org/jira/browse/KUDU-2198">KUDU-2198</a>).</p>
 </li>
 <li>
 <p>The performance of the compaction scheduler has been improved. In
 previous versions, certain types of time series workloads were found to
 cause compaction scheduling to take tens of seconds. These workloads now
 schedule compactions an order of magnitude more efficiently.</p>
 </li>
 <li>
 <p>The compaction scheduler has been improved to avoid running a compaction
 when the benefit of that compaction is extremely small.</p>
 </li>
 <li>
 <p>Tablet servers now consider the health of all replicas of a tablet before
 deciding to evict one. This can improve stability of the Kudu cluster after
 experiencing multiple simultaneous daemon failures
 (see <a href="https://issues.apache.org/jira/browse/KUDU-2048">KUDU-2048</a>).</p>
 </li>
 <li>
 <p>Several performance improvements have been made to the Kudu master,
 particularly in concurrency of clients opening tables. This should improve
 performance in highly concurrent workloads.</p>
 </li>
 <li>
 <p>The on-disk size metric for a tablet now includes all data and metadata.
 Previously, it excluded WAL segments and consensus metadata
 (see <a href="https://issues.apache.org/jira/browse/KUDU-1755">KUDU-1755</a>).</p>
 </li>
 <li>
 <p>Added verbose mode for the 'kudu cluster ksck' command to enable output
 of detailed information on the cluster&#8217;s metadata, even when no errors are
 detected.</p>
 </li>
 </ul>
 </div>
 </div>
 </div>
 <div class="sect1">
 <h2 id="rn_1.6.0_fixed_issues"><a class="link" href="#rn_1.6.0_fixed_issues">Fixed Issues</a></h2>
 <div class="sectionbody">
 <div class="ulist">
 <ul>
 <li>
 <p>HybridTime timestamp propagation now works in the Java client when using scan
 tokens (see <a href="https://issues.apache.org/jira/browse/KUDU-1411">KUDU-1411</a>).</p>
 </li>
 <li>
 <p>Fixed an error message commonly found in tablet server logs indicating that
 operations were being read "from the future"
 (see <a href="https://issues.apache.org/jira/browse/KUDU-1078">KUDU-1078</a>).</p>
 </li>
 <li>
 <p>Tombstoned tablets no longer report metrics
 (see <a href="https://issues.apache.org/jira/browse/KUDU-2044">KUDU-2044</a>).</p>
 </li>
 <li>
 <p>Fixed a bug in the C++ client which could cause tablets to be erroneously
 pruned, or skipped, during certain scans, resulting in fewer results than
 expected being returned from queries. The bug only affected tables whose range
 partition columns are a proper prefix of the primary key
 (see <a href="https://issues.apache.org/jira/browse/KUDU-2173">KUDU-2173</a>).</p>
 </li>
 <li>
 <p>Published Kudu Java artifacts are now fully compatible with JRE 7 and JRE 8.
 There was previously a bug in the release process which made them compatible
 only with JRE 8
 (see <a href="https://issues.apache.org/jira/browse/KUDU-2188">KUDU-2188</a>).</p>
 </li>
 <li>
 <p>Fixed a typo in the list of default TLS ciphers used by Kudu servers. As a
 result, two additional cipher suites are now available:</p>
 <div class="ulist">
 <ul>
 <li>
 <p>ECDHE-RSA-AES128-SHA256 TLSv1.2 Kx=ECDH Au=RSA Enc=AES(128)  Mac=SHA256</p>
 </li>
 <li>
 <p>AES256-GCM-SHA384       TLSv1.2 Kx=RSA  Au=RSA Enc=AESGCM(256) Mac=AEAD</p>
 </li>
 </ul>
 </div>
 </li>
 </ul>
 </div>
 </div>
 </div>
 <div class="sect1">
 <h2 id="rn_1.6.0_wire_compatibility"><a class="link" href="#rn_1.6.0_wire_compatibility">Wire Protocol compatibility</a></h2>
 <div class="sectionbody">
 <div class="paragraph">
 <p>Kudu 1.6.0 is wire-compatible with previous versions of Kudu:</p>
 </div>
 <div class="ulist">
 <ul>
 <li>
 <p>Kudu 1.6 clients may connect to servers running Kudu 1.0 or later. If the client uses
 features that are not available on the target server, an error will be returned.</p>
 </li>
 <li>
 <p>Rolling upgrade between Kudu 1.5 and Kudu 1.6 servers is believed to be possible
 though has not been sufficiently tested. Users are encouraged to shut down all nodes
 in the cluster, upgrade the software, and then restart the daemons on the new version.</p>
 </li>
 <li>
 <p>Kudu 1.0 clients may connect to servers running Kudu 1.6 with the exception of the
 below-mentioned restrictions regarding secure clusters.</p>
 </li>
 </ul>
 </div>
 <div class="paragraph">
 <p>The authentication features introduced in Kudu 1.3 place the following limitations
 on wire compatibility between Kudu 1.6 and versions earlier than 1.3:</p>
 </div>
 <div class="ulist">
 <ul>
 <li>
 <p>If a Kudu 1.6 cluster is configured with authentication or encryption set to "required",
 clients older than Kudu 1.3 will be unable to connect.</p>
 </li>
 <li>
 <p>If a Kudu 1.6 cluster is configured with authentication and encryption set to "optional"
 or "disabled", older clients will still be able to connect.</p>
 </li>
 </ul>
 </div>
 </div>
 </div>
 <div class="sect1">
 <h2 id="rn_1.6.0_incompatible_changes"><a class="link" href="#rn_1.6.0_incompatible_changes">Incompatible Changes in Kudu 1.6.0</a></h2>
 <div class="sectionbody">
 <div class="sect2">
 <h3 id="rn_1.6.0_client_compatibility"><a class="link" href="#rn_1.6.0_client_compatibility">Client Library Compatibility</a></h3>
 <div class="ulist">
 <ul>
 <li>
 <p>The Kudu 1.6 Java client library is API- and ABI-compatible with Kudu 1.5. Applications
 written against Kudu 1.5 will compile and run against the Kudu 1.6 client library and
 vice-versa.</p>
 </li>
 <li>
 <p>The Kudu 1.6 C++ client is API- and ABI-forward-compatible with Kudu 1.5.
 Applications written and compiled against the Kudu 1.5 client library will run without
 modification against the Kudu 1.6 client library. Applications written and compiled
 against the Kudu 1.6 client library will run without modification against the Kudu 1.5
 client library.</p>
 </li>
 <li>
 <p>The Kudu 1.6 Python client is API-compatible with Kudu 1.5. Applications
 written against Kudu 1.5 will continue to run against the Kudu 1.6 client
 and vice-versa.</p>
 </li>
 </ul>
 </div>
 </div>
 </div>
 </div>
 <div class="sect1">
 <h2 id="rn_1.6.0_known_issues"><a class="link" href="#rn_1.6.0_known_issues">Known Issues and Limitations</a></h2>
 <div class="sectionbody">
 <div class="paragraph">
 <p>Please refer to the <a href="known_issues.html">Known Issues and Limitations</a> section of the
 documentation.</p>
 </div>
 </div>
 </div>
 <div class="sect1">
 <h2 id="rn_1.6.0_contributors"><a class="link" href="#rn_1.6.0_contributors">Contributors</a></h2>
 <div class="sectionbody">
 <div class="paragraph">
 <p>Kudu 1.6 includes contributions from 14 people, including one
 first-time contributor, Hector Camarena.</p>
 </div>
 <div class="paragraph">
 <p>Thanks for helping to make Kudu even better!</p>
 </div>
 </div>
 </div>
 <div class="sect1">
 <h2 id="resources_and_next_steps"><a class="link" href="#resources_and_next_steps">Resources</a></h2>
 <div class="sectionbody">
 <div class="ulist">
 <ul>
 <li>
 <p><a href="http://kudu.apache.org">Kudu Website</a></p>
 </li>
 <li>
 <p><a href="http://github.com/apache/kudu">Kudu GitHub Repository</a></p>
 </li>
 <li>
 <p><a href="index.html">Kudu Documentation</a></p>
 </li>
 <li>
 <p><a href="prior_release_notes.html">Release notes for older releases</a></p>
 </li>
 </ul>
 </div>
 </div>
 </div>
 <div class="sect1">
 <h2 id="_installation_options"><a class="link" href="#_installation_options">Installation Options</a></h2>
 <div class="sectionbody">
 <div class="paragraph">
 <p>For full installation details, see <a href="installation.html">Kudu Installation</a>.</p>
 </div>
 </div>
 </div>
 <div class="sect1">
 <h2 id="_next_steps"><a class="link" href="#_next_steps">Next Steps</a></h2>
 <div class="sectionbody">
 <div class="ulist">
 <ul>
 <li>
 <p><a href="quickstart.html">Kudu Quickstart</a></p>
 </li>
 <li>
 <p><a href="installation.html">Installing Kudu</a></p>
 </li>
 <li>
 <p><a href="configuration.html">Configuring Kudu</a></p>
 </li>
 </ul>
 </div>
 </div>
 </div>
     </div>
     <div class="col-md-3">

   <div id="toc" data-spy="affix" data-offset-top="70">
   <ul>

       <li>

           <a href="index.html">Introducing Kudu</a>
       </li>
       <li>
 <span class="active-toc">Kudu Release Notes</span>
             <ul class="sectlevel1">
 <li><a href="#rn_1.6.0_upgrade_notes">Upgrade Notes</a></li>
 <li><a href="#rn_1.6.0_obsoletions">Obsoletions</a></li>
 <li><a href="#rn_1.6.0_deprecations">Deprecations</a></li>
 <li><a href="#rn_1.6.0_new_features">New features</a></li>
 <li><a href="#_optimizations_and_improvements">Optimizations and improvements</a></li>
 <li><a href="#rn_1.6.0_fixed_issues">Fixed Issues</a></li>
 <li><a href="#rn_1.6.0_wire_compatibility">Wire Protocol compatibility</a></li>
 <li><a href="#rn_1.6.0_incompatible_changes">Incompatible Changes in Kudu 1.6.0</a>
 <ul class="sectlevel2">
 <li><a href="#rn_1.6.0_client_compatibility">Client Library Compatibility</a></li>
 </ul>
 </li>
 <li><a href="#rn_1.6.0_known_issues">Known Issues and Limitations</a></li>
 <li><a href="#rn_1.6.0_contributors">Contributors</a></li>
 <li><a href="#resources_and_next_steps">Resources</a></li>
 <li><a href="#_installation_options">Installation Options</a></li>
 <li><a href="#_next_steps">Next Steps</a></li>
 </ul>
       </li>
       <li>

           <a href="quickstart.html">Getting Started with Kudu</a>
       </li>
       <li>

           <a href="installation.html">Installation Guide</a>
       </li>
       <li>

           <a href="configuration.html">Configuring Kudu</a>
       </li>
       <li>

           <a href="kudu_impala_integration.html">Using Impala with Kudu</a>
       </li>
       <li>

           <a href="administration.html">Administering Kudu</a>
       </li>
       <li>

           <a href="troubleshooting.html">Troubleshooting Kudu</a>
       </li>
       <li>

           <a href="developing.html">Developing Applications with Kudu</a>
       </li>
       <li>

           <a href="schema_design.html">Kudu Schema Design</a>
       </li>
       <li>

           <a href="security.html">Kudu Security</a>
       </li>
       <li>

           <a href="transaction_semantics.html">Kudu Transaction Semantics</a>
       </li>
       <li>

           <a href="background_tasks.html">Background Maintenance Tasks</a>
       </li>
       <li>

           <a href="configuration_reference.html">Kudu Configuration Reference</a>
       </li>
       <li>

           <a href="command_line_tools_reference.html">Kudu Command Line Tools Reference</a>
       </li>
       <li>

           <a href="known_issues.html">Known Issues and Limitations</a>
       </li>
       <li>

           <a href="contributing.html">Contributing to Kudu</a>
       </li>
       <li>

           <a href="export_control.html">Export Control Notice</a>
       </li>
   </ul>
   </div>
     </div>
   </div>
 </div>
	---
	title: Apache Kudu 1.6.0 Release Notes
	layout: default
	active_nav: docs
	last_updated: 'Last updated 2017-12-01 23:56:01 PST'
	---
	<!--

	Licensed under the Apache License, Version 2.0 (the "License");
	you may not use this file except in compliance with the License.
	You may obtain a copy of the License at

	http://www.apache.org/licenses/LICENSE-2.0

	Unless required by applicable law or agreed to in writing, software
	distributed under the License is distributed on an "AS IS" BASIS,
	WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	See the License for the specific language governing permissions and
	limitations under the License.
	-->


	<div class="container">
	<div class="row">
	<div class="col-md-9">

	<h1>Apache Kudu 1.6.0 Release Notes</h1>
	<div class="sect1">
	<h2 id="rn_1.6.0_upgrade_notes"><a class="link" href="#rn_1.6.0_upgrade_notes">Upgrade Notes</a></h2>
	<div class="sectionbody">
	<div class="ulist">
	<ul>
	<li>
	<p>Upgrading directly from Kudu 1.5.0 is supported and no special upgrade steps
	are required. A rolling upgrade may work, however it has not been tested.
	When upgrading Kudu, it is recommended to first shut down all Kudu processes
	across the cluster, then upgrade the software on all servers, then restart
	the Kudu processes on all servers in the cluster.</p>
	</li>
	</ul>
	</div>
	</div>
	</div>
	<div class="sect1">
	<h2 id="rn_1.6.0_obsoletions"><a class="link" href="#rn_1.6.0_obsoletions">Obsoletions</a></h2>
	<div class="sectionbody">
	<div class="ulist">
	<ul>
	<li>
	<p>Support for Spark 1 (kudu-spark_2.10) has been <strong>removed</strong> in Kudu 1.6.0 and
	now only Spark 2 is supported. Spark 1 support was deprecated in Kudu 1.5.0.</p>
	</li>
	</ul>
	</div>
	</div>
	</div>
	<div class="sect1">
	<h2 id="rn_1.6.0_deprecations"><a class="link" href="#rn_1.6.0_deprecations">Deprecations</a></h2>
	<div class="sectionbody">
	<div class="ulist">
	<ul>
	<li>
	<p>Support for Java 7 has been deprecated since Kudu 1.5.0 and may be removed in
	the next major release.</p>
	</li>
	</ul>
	</div>
	</div>
	</div>
	<div class="sect1">
	<h2 id="rn_1.6.0_new_features"><a class="link" href="#rn_1.6.0_new_features">New features</a></h2>
	<div class="sectionbody">
	<div class="ulist">
	<ul>
	<li>
	<p>Tablet servers' tolerance of disk failures is now enabled by default and has
	been extended to handle data directory failures at runtime. In the event of
	a disk failure at runtime, any tablets with data on a failed disk will be
	shut down and restarted on another tablet server. There is a configurable
	tradeoff between a newly added tablet’s tolerance to disk failures and its
	ability to parallelize reads via the experimental
	<code>--fs_target_data_dirs_per_tablet</code> flag. Tablets that are spread across fewer
	disks are less likely to be affected by a disk failure, at the cost of
	reduced parallelism. By default, tablets are striped across all available
	disks. Note that the first configured data directory and the WAL directory
	cannot currently tolerate disk failures. This will be further improved in
	future Kudu releases.</p>
	</li>
	<li>
	<p>Kudu servers can now adopt new data directories via the new
	<code>kudu fs update_dirs</code> tool. The new directory will be used by new tablet
	replicas only. Note that removing directories is not yet supported
	(see <a href="https://issues.apache.org/jira/browse/KUDU-2202">KUDU-2202</a>).</p>
	</li>
	<li>
	<p>Kudu servers have two new flags to control webui TLS/HTTPS
	settings: <code>--webserver_tls_ciphers</code> and <code>--webserver_tls_min_protocol</code>.
	These flags allow the advertised TLS ciphers and TLS protocol versions to be
	configured. Additionally, the webserver now excludes insecure legacy ciphers
	by default
	(see <a href="https://issues.apache.org/jira/browse/KUDU-2190">KUDU-2190</a>).</p>
	</li>
	</ul>
	</div>
	</div>
	</div>
	<div class="sect1">
	<h2 id="_optimizations_and_improvements"><a class="link" href="#_optimizations_and_improvements">Optimizations and improvements</a></h2>
	<div class="sectionbody">
	<div class="ulist">
	<ul>
	<li>
	<p>Kudu servers can now tolerate short interruptions in NTP clock
	synchronization. NTP synchronization is still required when any Kudu daemon
	starts up. If NTP synchronization is not available, diagnostic information
	is now logged to help pinpoint the issue
	(see <a href="https://issues.apache.org/jira/browse/KUDU-1578">KUDU-1578</a>).</p>
	</li>
	<li>
	<p>Tablet server startup time has been improved significantly on servers
	containing large numbers of blocks.</p>
	</li>
	<li>
	<p>The log block manager now performs disk data deletion in batches. This
	optimization can significantly reduce the time taken to delete data on a tablet.</p>
	</li>
	<li>
	<p>The usage of sensitive data redaction flag has been slightly changed. By
	setting <code>--redact=log</code> flag, redaction will be disabled in the web UI but
	retained for server logs. Alternatively, <code>--redact=none</code> can be used to
	disable redaction completely.</p>
	</li>
	<li>
	<p>The Spark DataSource integration now can take advantage of scan locality
	for better scan performance, the scan will take place at the closest replica
	instead of going to the leader.</p>
	</li>
	<li>
	<p>Various optimizations were made to reduce the 99th percentile latency of
	writes on the tablet server. This can also improve throughput on certain
	write workloads, particularly on larger clusters.</p>
	</li>
	<li>
	<p>Kudu may now be configured to ignore system-wide auth_to_local mappings
	configured in /etc/krb5.conf by setting the configuration flag
	<code>--use_system_auth_to_local=false</code>
	(see <a href="https://issues.apache.org/jira/browse/KUDU-2198">KUDU-2198</a>).</p>
	</li>
	<li>
	<p>The performance of the compaction scheduler has been improved. In
	previous versions, certain types of time series workloads were found to
	cause compaction scheduling to take tens of seconds. These workloads now
	schedule compactions an order of magnitude more efficiently.</p>
	</li>
	<li>
	<p>The compaction scheduler has been improved to avoid running a compaction
	when the benefit of that compaction is extremely small.</p>
	</li>
	<li>
	<p>Tablet servers now consider the health of all replicas of a tablet before
	deciding to evict one. This can improve stability of the Kudu cluster after
	experiencing multiple simultaneous daemon failures
	(see <a href="https://issues.apache.org/jira/browse/KUDU-2048">KUDU-2048</a>).</p>
	</li>
	<li>
	<p>Several performance improvements have been made to the Kudu master,
	particularly in concurrency of clients opening tables. This should improve
	performance in highly concurrent workloads.</p>
	</li>
	<li>
	<p>The on-disk size metric for a tablet now includes all data and metadata.
	Previously, it excluded WAL segments and consensus metadata
	(see <a href="https://issues.apache.org/jira/browse/KUDU-1755">KUDU-1755</a>).</p>
	</li>
	<li>
	<p>Added verbose mode for the 'kudu cluster ksck' command to enable output
	of detailed information on the cluster’s metadata, even when no errors are
	detected.</p>
	</li>
	</ul>
	</div>
	</div>
	</div>
	<div class="sect1">
	<h2 id="rn_1.6.0_fixed_issues"><a class="link" href="#rn_1.6.0_fixed_issues">Fixed Issues</a></h2>
	<div class="sectionbody">
	<div class="ulist">
	<ul>
	<li>
	<p>HybridTime timestamp propagation now works in the Java client when using scan
	tokens (see <a href="https://issues.apache.org/jira/browse/KUDU-1411">KUDU-1411</a>).</p>
	</li>
	<li>
	<p>Fixed an error message commonly found in tablet server logs indicating that
	operations were being read "from the future"
	(see <a href="https://issues.apache.org/jira/browse/KUDU-1078">KUDU-1078</a>).</p>
	</li>
	<li>
	<p>Tombstoned tablets no longer report metrics
	(see <a href="https://issues.apache.org/jira/browse/KUDU-2044">KUDU-2044</a>).</p>
	</li>
	<li>
	<p>Fixed a bug in the C++ client which could cause tablets to be erroneously
	pruned, or skipped, during certain scans, resulting in fewer results than
	expected being returned from queries. The bug only affected tables whose range
	partition columns are a proper prefix of the primary key
	(see <a href="https://issues.apache.org/jira/browse/KUDU-2173">KUDU-2173</a>).</p>
	</li>
	<li>
	<p>Published Kudu Java artifacts are now fully compatible with JRE 7 and JRE 8.
	There was previously a bug in the release process which made them compatible
	only with JRE 8
	(see <a href="https://issues.apache.org/jira/browse/KUDU-2188">KUDU-2188</a>).</p>
	</li>
	<li>
	<p>Fixed a typo in the list of default TLS ciphers used by Kudu servers. As a
	result, two additional cipher suites are now available:</p>
	<div class="ulist">
	<ul>
	<li>
	<p>ECDHE-RSA-AES128-SHA256 TLSv1.2 Kx=ECDH Au=RSA Enc=AES(128) Mac=SHA256</p>
	</li>
	<li>
	<p>AES256-GCM-SHA384 TLSv1.2 Kx=RSA Au=RSA Enc=AESGCM(256) Mac=AEAD</p>
	</li>
	</ul>
	</div>
	</li>
	</ul>
	</div>
	</div>
	</div>
	<div class="sect1">
	<h2 id="rn_1.6.0_wire_compatibility"><a class="link" href="#rn_1.6.0_wire_compatibility">Wire Protocol compatibility</a></h2>
	<div class="sectionbody">
	<div class="paragraph">
	<p>Kudu 1.6.0 is wire-compatible with previous versions of Kudu:</p>
	</div>
	<div class="ulist">
	<ul>
	<li>
	<p>Kudu 1.6 clients may connect to servers running Kudu 1.0 or later. If the client uses
	features that are not available on the target server, an error will be returned.</p>
	</li>
	<li>
	<p>Rolling upgrade between Kudu 1.5 and Kudu 1.6 servers is believed to be possible
	though has not been sufficiently tested. Users are encouraged to shut down all nodes
	in the cluster, upgrade the software, and then restart the daemons on the new version.</p>
	</li>
	<li>
	<p>Kudu 1.0 clients may connect to servers running Kudu 1.6 with the exception of the
	below-mentioned restrictions regarding secure clusters.</p>
	</li>
	</ul>
	</div>
	<div class="paragraph">
	<p>The authentication features introduced in Kudu 1.3 place the following limitations
	on wire compatibility between Kudu 1.6 and versions earlier than 1.3:</p>
	</div>
	<div class="ulist">
	<ul>
	<li>
	<p>If a Kudu 1.6 cluster is configured with authentication or encryption set to "required",
	clients older than Kudu 1.3 will be unable to connect.</p>
	</li>
	<li>
	<p>If a Kudu 1.6 cluster is configured with authentication and encryption set to "optional"
	or "disabled", older clients will still be able to connect.</p>
	</li>
	</ul>
	</div>
	</div>
	</div>
	<div class="sect1">
	<h2 id="rn_1.6.0_incompatible_changes"><a class="link" href="#rn_1.6.0_incompatible_changes">Incompatible Changes in Kudu 1.6.0</a></h2>
	<div class="sectionbody">
	<div class="sect2">
	<h3 id="rn_1.6.0_client_compatibility"><a class="link" href="#rn_1.6.0_client_compatibility">Client Library Compatibility</a></h3>
	<div class="ulist">
	<ul>
	<li>
	<p>The Kudu 1.6 Java client library is API- and ABI-compatible with Kudu 1.5. Applications
	written against Kudu 1.5 will compile and run against the Kudu 1.6 client library and
	vice-versa.</p>
	</li>
	<li>
	<p>The Kudu 1.6 C++ client is API- and ABI-forward-compatible with Kudu 1.5.
	Applications written and compiled against the Kudu 1.5 client library will run without
	modification against the Kudu 1.6 client library. Applications written and compiled
	against the Kudu 1.6 client library will run without modification against the Kudu 1.5
	client library.</p>
	</li>
	<li>
	<p>The Kudu 1.6 Python client is API-compatible with Kudu 1.5. Applications
	written against Kudu 1.5 will continue to run against the Kudu 1.6 client
	and vice-versa.</p>
	</li>
	</ul>
	</div>
	</div>
	</div>
	</div>
	<div class="sect1">
	<h2 id="rn_1.6.0_known_issues"><a class="link" href="#rn_1.6.0_known_issues">Known Issues and Limitations</a></h2>
	<div class="sectionbody">
	<div class="paragraph">
	<p>Please refer to the <a href="known_issues.html">Known Issues and Limitations</a> section of the
	documentation.</p>
	</div>
	</div>
	</div>
	<div class="sect1">
	<h2 id="rn_1.6.0_contributors"><a class="link" href="#rn_1.6.0_contributors">Contributors</a></h2>
	<div class="sectionbody">
	<div class="paragraph">
	<p>Kudu 1.6 includes contributions from 14 people, including one
	first-time contributor, Hector Camarena.</p>
	</div>
	<div class="paragraph">
	<p>Thanks for helping to make Kudu even better!</p>
	</div>
	</div>
	</div>
	<div class="sect1">
	<h2 id="resources_and_next_steps"><a class="link" href="#resources_and_next_steps">Resources</a></h2>
	<div class="sectionbody">
	<div class="ulist">
	<ul>
	<li>
	<p><a href="http://kudu.apache.org">Kudu Website</a></p>
	</li>
	<li>
	<p><a href="http://github.com/apache/kudu">Kudu GitHub Repository</a></p>
	</li>
	<li>
	<p><a href="index.html">Kudu Documentation</a></p>
	</li>
	<li>
	<p><a href="prior_release_notes.html">Release notes for older releases</a></p>
	</li>
	</ul>
	</div>
	</div>
	</div>
	<div class="sect1">
	<h2 id="_installation_options"><a class="link" href="#_installation_options">Installation Options</a></h2>
	<div class="sectionbody">
	<div class="paragraph">
	<p>For full installation details, see <a href="installation.html">Kudu Installation</a>.</p>
	</div>
	</div>
	</div>
	<div class="sect1">
	<h2 id="_next_steps"><a class="link" href="#_next_steps">Next Steps</a></h2>
	<div class="sectionbody">
	<div class="ulist">
	<ul>
	<li>
	<p><a href="quickstart.html">Kudu Quickstart</a></p>
	</li>
	<li>
	<p><a href="installation.html">Installing Kudu</a></p>
	</li>
	<li>
	<p><a href="configuration.html">Configuring Kudu</a></p>
	</li>
	</ul>
	</div>
	</div>
	</div>
	</div>
	<div class="col-md-3">

	<div id="toc" data-spy="affix" data-offset-top="70">
	<ul>

	<li>

	<a href="index.html">Introducing Kudu</a>
	</li>
	<li>
	<span class="active-toc">Kudu Release Notes</span>
	<ul class="sectlevel1">
	<li><a href="#rn_1.6.0_upgrade_notes">Upgrade Notes</a></li>
	<li><a href="#rn_1.6.0_obsoletions">Obsoletions</a></li>
	<li><a href="#rn_1.6.0_deprecations">Deprecations</a></li>
	<li><a href="#rn_1.6.0_new_features">New features</a></li>
	<li><a href="#_optimizations_and_improvements">Optimizations and improvements</a></li>
	<li><a href="#rn_1.6.0_fixed_issues">Fixed Issues</a></li>
	<li><a href="#rn_1.6.0_wire_compatibility">Wire Protocol compatibility</a></li>
	<li><a href="#rn_1.6.0_incompatible_changes">Incompatible Changes in Kudu 1.6.0</a>
	<ul class="sectlevel2">
	<li><a href="#rn_1.6.0_client_compatibility">Client Library Compatibility</a></li>
	</ul>
	</li>
	<li><a href="#rn_1.6.0_known_issues">Known Issues and Limitations</a></li>
	<li><a href="#rn_1.6.0_contributors">Contributors</a></li>
	<li><a href="#resources_and_next_steps">Resources</a></li>
	<li><a href="#_installation_options">Installation Options</a></li>
	<li><a href="#_next_steps">Next Steps</a></li>
	</ul>
	</li>
	<li>

	<a href="quickstart.html">Getting Started with Kudu</a>
	</li>
	<li>

	<a href="installation.html">Installation Guide</a>
	</li>
	<li>

	<a href="configuration.html">Configuring Kudu</a>
	</li>
	<li>

	<a href="kudu_impala_integration.html">Using Impala with Kudu</a>
	</li>
	<li>

	<a href="administration.html">Administering Kudu</a>
	</li>
	<li>

	<a href="troubleshooting.html">Troubleshooting Kudu</a>
	</li>
	<li>

	<a href="developing.html">Developing Applications with Kudu</a>
	</li>
	<li>

	<a href="schema_design.html">Kudu Schema Design</a>
	</li>
	<li>

	<a href="security.html">Kudu Security</a>
	</li>
	<li>

	<a href="transaction_semantics.html">Kudu Transaction Semantics</a>
	</li>
	<li>

	<a href="background_tasks.html">Background Maintenance Tasks</a>
	</li>
	<li>

	<a href="configuration_reference.html">Kudu Configuration Reference</a>
	</li>
	<li>

	<a href="command_line_tools_reference.html">Kudu Command Line Tools Reference</a>
	</li>
	<li>

	<a href="known_issues.html">Known Issues and Limitations</a>
	</li>
	<li>

	<a href="contributing.html">Contributing to Kudu</a>
	</li>
	<li>

	<a href="export_control.html">Export Control Notice</a>
	</li>
	</ul>
	</div>
	</div>
	</div>
	</div>