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 title: Known Issues and Limitations
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 <div class="container">
   <div class="row">
     <div class="col-md-9">

 <h1>Known Issues and Limitations</h1>
       <div id="preamble">
 <div class="sectionbody">
 <div class="admonitionblock note">
 <table>
 <tr>
 <td class="icon">
 <i class="fa icon-note" title="Note"></i>
 </td>
 <td class="content">
 This document applies to Apache Kudu version 1.17.1. Please consult the
 <a href="http://kudu.apache.org/releases/">documentation of the appropriate release</a> that&#8217;s applicable
 to the version of the Kudu cluster.
 </td>
 </tr>
 </table>
 </div>
 </div>
 </div>
 <div class="sect1">
 <h2 id="_schema"><a class="link" href="#_schema">Schema</a></h2>
 <div class="sectionbody">
 <div class="sect2">
 <h3 id="_primary_keys"><a class="link" href="#_primary_keys">Primary keys</a></h3>
 <div class="ulist">
 <ul>
 <li>
 <p>The primary key may not be changed after the table is created.
 You must drop and recreate a table to select a new primary key.</p>
 </li>
 <li>
 <p>The columns which make up the primary key must be listed first in the schema.</p>
 </li>
 <li>
 <p>The primary key of a row may not be modified using the <code>UPDATE</code> functionality.
 To modify a row&#8217;s primary key, the row must be deleted and re-inserted with
 the modified key. Such a modification is non-atomic.</p>
 </li>
 <li>
 <p>Columns with <code>DOUBLE</code>, <code>FLOAT</code>, or <code>BOOL</code> types are not allowed as part of a
 primary key definition. Additionally, all columns that are part of a primary
 key definition must be <code>NOT NULL</code>.</p>
 </li>
 <li>
 <p>Auto-generated primary keys are not supported.</p>
 </li>
 <li>
 <p>Cells making up a composite primary key are limited to a total of 16KiB after the internal
 composite-key encoding done by Kudu.</p>
 </li>
 </ul>
 </div>
 </div>
 <div class="sect2">
 <h3 id="_columns"><a class="link" href="#_columns">Columns</a></h3>
 <div class="ulist">
 <ul>
 <li>
 <p><code>CHAR</code> and complex types like <code>ARRAY</code>, <code>MAP</code>, and <code>STRUCT</code> are not yet
 supported.</p>
 </li>
 <li>
 <p>Type, nullability and type attributes (i.e. precision and scale of <code>DECIMAL</code>,
 length of <code>VARCHAR</code>) of existing columns cannot be changed by altering the
 table.</p>
 </li>
 <li>
 <p>Tables can have a maximum of 300 columns by default.</p>
 </li>
 </ul>
 </div>
 </div>
 <div class="sect2">
 <h3 id="_tables"><a class="link" href="#_tables">Tables</a></h3>
 <div class="ulist">
 <ul>
 <li>
 <p>Tables must have an odd number of replicas, with a maximum of 7.</p>
 </li>
 <li>
 <p>The replication factor is set at table creation time and cannot be changed
 later. As a workaround, create a new table with the same schema and
 the desired replication factor and insert the contents of the old table
 into the new one.</p>
 </li>
 </ul>
 </div>
 </div>
 <div class="sect2">
 <h3 id="_cells_individual_values"><a class="link" href="#_cells_individual_values">Cells (individual values)</a></h3>
 <div class="ulist">
 <ul>
 <li>
 <p>By default, cells cannot be larger than 64KiB before encoding or compression.</p>
 </li>
 </ul>
 </div>
 </div>
 <div class="sect2">
 <h3 id="_other_usage_limitations"><a class="link" href="#_other_usage_limitations">Other usage limitations</a></h3>
 <div class="ulist">
 <ul>
 <li>
 <p>Secondary indexes are not supported.</p>
 </li>
 <li>
 <p>Multi-row transactions are not yet supported.</p>
 </li>
 <li>
 <p>Relational features, like foreign keys, are not supported.</p>
 </li>
 <li>
 <p>Identifiers such as column and table names are restricted to be valid UTF-8 strings.
 Additionally, a maximum length of 256 characters is enforced.</p>
 </li>
 <li>
 <p>Dropping a column does not immediately reclaim space. Compaction must run first.</p>
 </li>
 <li>
 <p>There is no way to run compaction manually, but dropping the table will reclaim the
 space immediately.</p>
 </li>
 </ul>
 </div>
 </div>
 </div>
 </div>
 <div class="sect1">
 <h2 id="_partitioning_limitations"><a class="link" href="#_partitioning_limitations">Partitioning Limitations</a></h2>
 <div class="sectionbody">
 <div class="ulist">
 <ul>
 <li>
 <p>Tables must be manually pre-split into tablets using simple or compound primary
 keys. Automatic splitting is not yet possible. Range partitions may be added
 or dropped after a table has been created. See
 <a href="schema_design.html#schema_design">Schema Design</a> for more information.</p>
 </li>
 <li>
 <p>Data in existing tables cannot currently be automatically repartitioned. As a workaround,
 create a new table with the new partitioning and insert the contents of the old
 table.</p>
 </li>
 <li>
 <p>Tablets that lose a majority of replicas (such as 1 left out of 3) require manual
 intervention to be repaired.</p>
 </li>
 </ul>
 </div>
 </div>
 </div>
 <div class="sect1">
 <h2 id="_cluster_management"><a class="link" href="#_cluster_management">Cluster management</a></h2>
 <div class="sectionbody">
 <div class="ulist">
 <ul>
 <li>
 <p>Recommended maximum point-to-point latency within a Kudu cluster is 20 milliseconds.</p>
 </li>
 <li>
 <p>Recommended minimum point-to-point bandwidth within a Kudu cluster is 10 Gbps.</p>
 </li>
 <li>
 <p>If you intend to use the location awareness feature to place tablet servers in
 different locations, it is recommended to measure the bandwidth and latency between servers
 to ensure they fit within the above guidelines.</p>
 </li>
 <li>
 <p>All masters must be started at the same time when the cluster is started for the very first time.</p>
 </li>
 </ul>
 </div>
 </div>
 </div>
 <div class="sect1">
 <h2 id="_server_management"><a class="link" href="#_server_management">Server management</a></h2>
 <div class="sectionbody">
 <div class="ulist">
 <ul>
 <li>
 <p>Production deployments should configure a least 4 GiB of memory for tablet servers,
 and ideally more than 16 GiB when approaching the data and tablet <a href="#_scale">Scale</a> limits.</p>
 </li>
 <li>
 <p>Write ahead logs (WAL) can only be stored on one disk.</p>
 </li>
 <li>
 <p>Tablet servers can’t change address/port.</p>
 </li>
 <li>
 <p>Kudu has a requirement on having the server-side clock synchronized with NTP.
 Kudu masters and tablet servers crash if detecting that the clock is out of
 sync. For the clock synchronization, either synchronize the local clock
 using an NTP server such as <code>ntpd</code> or <code>chronyd</code>, or use the built-in NTP
 client for Kudu masters and tablet servers.</p>
 </li>
 </ul>
 </div>
 </div>
 </div>
 <div class="sect1">
 <h2 id="_scale"><a class="link" href="#_scale">Scale</a></h2>
 <div class="sectionbody">
 <div class="paragraph">
 <p>Kudu is known to run seamlessly across a wide array of environments and workloads
 with minimal expertise and configuration at the following scale:</p>
 </div>
 <div class="ulist">
 <ul>
 <li>
 <p>3 master servers</p>
 </li>
 <li>
 <p>100 tablet servers</p>
 </li>
 <li>
 <p>8 TiB of stored data per tablet server, post-replication and post-compression.</p>
 </li>
 <li>
 <p>1000 tablets per tablet server, post-replication.</p>
 </li>
 <li>
 <p>60 tablets per table, per tablet server, at table-creation time.</p>
 </li>
 <li>
 <p>10 GiB of stored data per tablet.</p>
 </li>
 </ul>
 </div>
 <div class="paragraph">
 <p>Staying within these limits will provide the most predictable and straightforward
 Kudu experience.</p>
 </div>
 <div class="paragraph">
 <p>However, experienced users who run on modern hardware, use the latest
 versions of Kudu, test and tune Kudu for their use case, and work closely with
 the community, can achieve much higher scales comfortably. Below are some
 anecdotal values that have been seen in real world production clusters:</p>
 </div>
 <div class="ulist">
 <ul>
 <li>
 <p>3 master servers</p>
 </li>
 <li>
 <p>300+ tablet servers</p>
 </li>
 <li>
 <p>10+ TiB of stored data per tablet server, post-replication and post-compression.</p>
 </li>
 <li>
 <p>4000+ tablets per tablet server, post-replication.</p>
 </li>
 <li>
 <p>50 GiB of stored data per tablet. Going beyond this can cause issues such a
 reduced performance, compaction issues, and slow tablet startup times.</p>
 </li>
 </ul>
 </div>
 </div>
 </div>
 <div class="sect1">
 <h2 id="_security_limitations"><a class="link" href="#_security_limitations">Security Limitations</a></h2>
 <div class="sectionbody">
 <div class="ulist">
 <ul>
 <li>
 <p>Row-level authorization is not available.</p>
 </li>
 <li>
 <p>Data encryption at rest is not directly built into Kudu. Encryption of
 Kudu data at rest can be achieved through the use of local block device
 encryption software such as <code>dmcrypt</code>.</p>
 </li>
 <li>
 <p>Server certificates generated by Kudu IPKI are incompatible with
 <a href="https://www.bouncycastle.org/">bouncycastle</a> version 1.52 and earlier. See
 <a href="https://issues.apache.org/jira/browse/KUDU-2145">KUDU-2145</a> for details.</p>
 </li>
 </ul>
 </div>
 </div>
 </div>
 <div class="sect1">
 <h2 id="_other_known_issues"><a class="link" href="#_other_known_issues">Other Known Issues</a></h2>
 <div class="sectionbody">
 <div class="paragraph">
 <p>The following are known bugs and issues with the current release of Kudu. They will
 be addressed in later releases. Note that this list is not exhaustive, and is meant
 to communicate only the most important known issues.</p>
 </div>
 <div class="ulist">
 <ul>
 <li>
 <p>If a tablet server has a very large number of tablets, it may take several minutes
 to start up. It is recommended to limit the number of tablets per server to 1000
 or fewer. Consider this limitation when pre-splitting your tables. If you notice slow
 start-up times, you can monitor the number of tablets per server in the web UI.</p>
 </li>
 <li>
 <p>NVM-based cache doesn&#8217;t work reliably on RH6/CentOS6
 (see <a href="https://issues.apache.org/jira/browse/KUDU-2978">KUDU-2978</a>).</p>
 </li>
 <li>
 <p>When upgrading a Kudu cluster to 1.11.0 version with existing pre-1.11.0
 tables, the <code>live_row_count</code> and <code>on_disk_size</code> metrics might produce
 inconsistent readings in some scenarios
 (see <a href="https://issues.apache.org/jira/browse/KUDU-2986">KUDU-2986</a>).</p>
 </li>
 <li>
 <p>In Kudu 1.10.0 and Kudu 1.11.0, the kudu-binary JAR (targeted for
 containerized Kudu deployments using mini-cluster) contains libnuma dynamic
 library. Also, if building Kudu binaries in release mode with default cmake
 settings, the libnuma library is linked statically with the Kudu binaries
 (add <code>-DKUDU_LINK=dynamic</code> when running cmake to avoid that). The library is
 licensed under LGPL v.2.1, however the ASF thirdparty license policy
 explicitly prohibits including such contents into releases: see
 <a href="https://www.apache.org/legal/resolved.html#category-x">Category X</a>. This
 issue has been addressed in 1.10.1 and 1.11.1 patch releases correspondingly
 (see <a href="https://issues.apache.org/jira/browse/KUDU-2990">KUDU-2990</a>).</p>
 </li>
 <li>
 <p>Due to a bug in SSSD PAC plugin of version prior to 1.16, a KRPC connection
 negotiation may stuck and the whole process wouldn&#8217;t be able to negotiate
 any new connection for about 5 minutes in a secure Kudu cluster using SSSD.
 If using SSSD in secure Kudu cluster deployments, make sure SSSD packages are
 of version 1.16 or newer
 (see <a href="https://issues.apache.org/jira/browse/KUDU-3217">KUDU-3217</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>

           <a href="release_notes.html">Kudu Release Notes</a>
       </li>
       <li>

           <a href="quickstart.html">Quickstart Guide</a>
       </li>
       <li>

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

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

           <a href="hive_metastore.html">Using the Hive Metastore with 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="scaling_guide.html">Kudu Scaling Guide</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="metrics_reference.html">Kudu Metrics Reference</a>
       </li>
       <li>
 <span class="active-toc">Known Issues and Limitations</span>
             <ul class="sectlevel1">
 <li><a href="#_schema">Schema</a>
 <ul class="sectlevel2">
 <li><a href="#_primary_keys">Primary keys</a></li>
 <li><a href="#_columns">Columns</a></li>
 <li><a href="#_tables">Tables</a></li>
 <li><a href="#_cells_individual_values">Cells (individual values)</a></li>
 <li><a href="#_other_usage_limitations">Other usage limitations</a></li>
 </ul>
 </li>
 <li><a href="#_partitioning_limitations">Partitioning Limitations</a></li>
 <li><a href="#_cluster_management">Cluster management</a></li>
 <li><a href="#_server_management">Server management</a></li>
 <li><a href="#_scale">Scale</a></li>
 <li><a href="#_security_limitations">Security Limitations</a></li>
 <li><a href="#_other_known_issues">Other Known Issues</a></li>
 </ul>
       </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: Known Issues and Limitations
	layout: default
	active_nav: docs
	last_updated: 'Last updated 2024-10-28 17:39:22 -0700'
	---
	<!--

	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>Known Issues and Limitations</h1>
	<div id="preamble">
	<div class="sectionbody">
	<div class="admonitionblock note">
	<table>
	<tr>
	<td class="icon">
	<i class="fa icon-note" title="Note"></i>
	</td>
	<td class="content">
	This document applies to Apache Kudu version 1.17.1. Please consult the
	<a href="http://kudu.apache.org/releases/">documentation of the appropriate release</a> that’s applicable
	to the version of the Kudu cluster.
	</td>
	</tr>
	</table>
	</div>
	</div>
	</div>
	<div class="sect1">
	<h2 id="_schema"><a class="link" href="#_schema">Schema</a></h2>
	<div class="sectionbody">
	<div class="sect2">
	<h3 id="_primary_keys"><a class="link" href="#_primary_keys">Primary keys</a></h3>
	<div class="ulist">
	<ul>
	<li>
	<p>The primary key may not be changed after the table is created.
	You must drop and recreate a table to select a new primary key.</p>
	</li>
	<li>
	<p>The columns which make up the primary key must be listed first in the schema.</p>
	</li>
	<li>
	<p>The primary key of a row may not be modified using the <code>UPDATE</code> functionality.
	To modify a row’s primary key, the row must be deleted and re-inserted with
	the modified key. Such a modification is non-atomic.</p>
	</li>
	<li>
	<p>Columns with <code>DOUBLE</code>, <code>FLOAT</code>, or <code>BOOL</code> types are not allowed as part of a
	primary key definition. Additionally, all columns that are part of a primary
	key definition must be <code>NOT NULL</code>.</p>
	</li>
	<li>
	<p>Auto-generated primary keys are not supported.</p>
	</li>
	<li>
	<p>Cells making up a composite primary key are limited to a total of 16KiB after the internal
	composite-key encoding done by Kudu.</p>
	</li>
	</ul>
	</div>
	</div>
	<div class="sect2">
	<h3 id="_columns"><a class="link" href="#_columns">Columns</a></h3>
	<div class="ulist">
	<ul>
	<li>
	<p><code>CHAR</code> and complex types like <code>ARRAY</code>, <code>MAP</code>, and <code>STRUCT</code> are not yet
	supported.</p>
	</li>
	<li>
	<p>Type, nullability and type attributes (i.e. precision and scale of <code>DECIMAL</code>,
	length of <code>VARCHAR</code>) of existing columns cannot be changed by altering the
	table.</p>
	</li>
	<li>
	<p>Tables can have a maximum of 300 columns by default.</p>
	</li>
	</ul>
	</div>
	</div>
	<div class="sect2">
	<h3 id="_tables"><a class="link" href="#_tables">Tables</a></h3>
	<div class="ulist">
	<ul>
	<li>
	<p>Tables must have an odd number of replicas, with a maximum of 7.</p>
	</li>
	<li>
	<p>The replication factor is set at table creation time and cannot be changed
	later. As a workaround, create a new table with the same schema and
	the desired replication factor and insert the contents of the old table
	into the new one.</p>
	</li>
	</ul>
	</div>
	</div>
	<div class="sect2">
	<h3 id="_cells_individual_values"><a class="link" href="#_cells_individual_values">Cells (individual values)</a></h3>
	<div class="ulist">
	<ul>
	<li>
	<p>By default, cells cannot be larger than 64KiB before encoding or compression.</p>
	</li>
	</ul>
	</div>
	</div>
	<div class="sect2">
	<h3 id="_other_usage_limitations"><a class="link" href="#_other_usage_limitations">Other usage limitations</a></h3>
	<div class="ulist">
	<ul>
	<li>
	<p>Secondary indexes are not supported.</p>
	</li>
	<li>
	<p>Multi-row transactions are not yet supported.</p>
	</li>
	<li>
	<p>Relational features, like foreign keys, are not supported.</p>
	</li>
	<li>
	<p>Identifiers such as column and table names are restricted to be valid UTF-8 strings.
	Additionally, a maximum length of 256 characters is enforced.</p>
	</li>
	<li>
	<p>Dropping a column does not immediately reclaim space. Compaction must run first.</p>
	</li>
	<li>
	<p>There is no way to run compaction manually, but dropping the table will reclaim the
	space immediately.</p>
	</li>
	</ul>
	</div>
	</div>
	</div>
	</div>
	<div class="sect1">
	<h2 id="_partitioning_limitations"><a class="link" href="#_partitioning_limitations">Partitioning Limitations</a></h2>
	<div class="sectionbody">
	<div class="ulist">
	<ul>
	<li>
	<p>Tables must be manually pre-split into tablets using simple or compound primary
	keys. Automatic splitting is not yet possible. Range partitions may be added
	or dropped after a table has been created. See
	<a href="schema_design.html#schema_design">Schema Design</a> for more information.</p>
	</li>
	<li>
	<p>Data in existing tables cannot currently be automatically repartitioned. As a workaround,
	create a new table with the new partitioning and insert the contents of the old
	table.</p>
	</li>
	<li>
	<p>Tablets that lose a majority of replicas (such as 1 left out of 3) require manual
	intervention to be repaired.</p>
	</li>
	</ul>
	</div>
	</div>
	</div>
	<div class="sect1">
	<h2 id="_cluster_management"><a class="link" href="#_cluster_management">Cluster management</a></h2>
	<div class="sectionbody">
	<div class="ulist">
	<ul>
	<li>
	<p>Recommended maximum point-to-point latency within a Kudu cluster is 20 milliseconds.</p>
	</li>
	<li>
	<p>Recommended minimum point-to-point bandwidth within a Kudu cluster is 10 Gbps.</p>
	</li>
	<li>
	<p>If you intend to use the location awareness feature to place tablet servers in
	different locations, it is recommended to measure the bandwidth and latency between servers
	to ensure they fit within the above guidelines.</p>
	</li>
	<li>
	<p>All masters must be started at the same time when the cluster is started for the very first time.</p>
	</li>
	</ul>
	</div>
	</div>
	</div>
	<div class="sect1">
	<h2 id="_server_management"><a class="link" href="#_server_management">Server management</a></h2>
	<div class="sectionbody">
	<div class="ulist">
	<ul>
	<li>
	<p>Production deployments should configure a least 4 GiB of memory for tablet servers,
	and ideally more than 16 GiB when approaching the data and tablet <a href="#_scale">Scale</a> limits.</p>
	</li>
	<li>
	<p>Write ahead logs (WAL) can only be stored on one disk.</p>
	</li>
	<li>
	<p>Tablet servers can’t change address/port.</p>
	</li>
	<li>
	<p>Kudu has a requirement on having the server-side clock synchronized with NTP.
	Kudu masters and tablet servers crash if detecting that the clock is out of
	sync. For the clock synchronization, either synchronize the local clock
	using an NTP server such as <code>ntpd</code> or <code>chronyd</code>, or use the built-in NTP
	client for Kudu masters and tablet servers.</p>
	</li>
	</ul>
	</div>
	</div>
	</div>
	<div class="sect1">
	<h2 id="_scale"><a class="link" href="#_scale">Scale</a></h2>
	<div class="sectionbody">
	<div class="paragraph">
	<p>Kudu is known to run seamlessly across a wide array of environments and workloads
	with minimal expertise and configuration at the following scale:</p>
	</div>
	<div class="ulist">
	<ul>
	<li>
	<p>3 master servers</p>
	</li>
	<li>
	<p>100 tablet servers</p>
	</li>
	<li>
	<p>8 TiB of stored data per tablet server, post-replication and post-compression.</p>
	</li>
	<li>
	<p>1000 tablets per tablet server, post-replication.</p>
	</li>
	<li>
	<p>60 tablets per table, per tablet server, at table-creation time.</p>
	</li>
	<li>
	<p>10 GiB of stored data per tablet.</p>
	</li>
	</ul>
	</div>
	<div class="paragraph">
	<p>Staying within these limits will provide the most predictable and straightforward
	Kudu experience.</p>
	</div>
	<div class="paragraph">
	<p>However, experienced users who run on modern hardware, use the latest
	versions of Kudu, test and tune Kudu for their use case, and work closely with
	the community, can achieve much higher scales comfortably. Below are some
	anecdotal values that have been seen in real world production clusters:</p>
	</div>
	<div class="ulist">
	<ul>
	<li>
	<p>3 master servers</p>
	</li>
	<li>
	<p>300+ tablet servers</p>
	</li>
	<li>
	<p>10+ TiB of stored data per tablet server, post-replication and post-compression.</p>
	</li>
	<li>
	<p>4000+ tablets per tablet server, post-replication.</p>
	</li>
	<li>
	<p>50 GiB of stored data per tablet. Going beyond this can cause issues such a
	reduced performance, compaction issues, and slow tablet startup times.</p>
	</li>
	</ul>
	</div>
	</div>
	</div>
	<div class="sect1">
	<h2 id="_security_limitations"><a class="link" href="#_security_limitations">Security Limitations</a></h2>
	<div class="sectionbody">
	<div class="ulist">
	<ul>
	<li>
	<p>Row-level authorization is not available.</p>
	</li>
	<li>
	<p>Data encryption at rest is not directly built into Kudu. Encryption of
	Kudu data at rest can be achieved through the use of local block device
	encryption software such as <code>dmcrypt</code>.</p>
	</li>
	<li>
	<p>Server certificates generated by Kudu IPKI are incompatible with
	<a href="https://www.bouncycastle.org/">bouncycastle</a> version 1.52 and earlier. See
	<a href="https://issues.apache.org/jira/browse/KUDU-2145">KUDU-2145</a> for details.</p>
	</li>
	</ul>
	</div>
	</div>
	</div>
	<div class="sect1">
	<h2 id="_other_known_issues"><a class="link" href="#_other_known_issues">Other Known Issues</a></h2>
	<div class="sectionbody">
	<div class="paragraph">
	<p>The following are known bugs and issues with the current release of Kudu. They will
	be addressed in later releases. Note that this list is not exhaustive, and is meant
	to communicate only the most important known issues.</p>
	</div>
	<div class="ulist">
	<ul>
	<li>
	<p>If a tablet server has a very large number of tablets, it may take several minutes
	to start up. It is recommended to limit the number of tablets per server to 1000
	or fewer. Consider this limitation when pre-splitting your tables. If you notice slow
	start-up times, you can monitor the number of tablets per server in the web UI.</p>
	</li>
	<li>
	<p>NVM-based cache doesn’t work reliably on RH6/CentOS6
	(see <a href="https://issues.apache.org/jira/browse/KUDU-2978">KUDU-2978</a>).</p>
	</li>
	<li>
	<p>When upgrading a Kudu cluster to 1.11.0 version with existing pre-1.11.0
	tables, the <code>live_row_count</code> and <code>on_disk_size</code> metrics might produce
	inconsistent readings in some scenarios
	(see <a href="https://issues.apache.org/jira/browse/KUDU-2986">KUDU-2986</a>).</p>
	</li>
	<li>
	<p>In Kudu 1.10.0 and Kudu 1.11.0, the kudu-binary JAR (targeted for
	containerized Kudu deployments using mini-cluster) contains libnuma dynamic
	library. Also, if building Kudu binaries in release mode with default cmake
	settings, the libnuma library is linked statically with the Kudu binaries
	(add <code>-DKUDU_LINK=dynamic</code> when running cmake to avoid that). The library is
	licensed under LGPL v.2.1, however the ASF thirdparty license policy
	explicitly prohibits including such contents into releases: see
	<a href="https://www.apache.org/legal/resolved.html#category-x">Category X</a>. This
	issue has been addressed in 1.10.1 and 1.11.1 patch releases correspondingly
	(see <a href="https://issues.apache.org/jira/browse/KUDU-2990">KUDU-2990</a>).</p>
	</li>
	<li>
	<p>Due to a bug in SSSD PAC plugin of version prior to 1.16, a KRPC connection
	negotiation may stuck and the whole process wouldn’t be able to negotiate
	any new connection for about 5 minutes in a secure Kudu cluster using SSSD.
	If using SSSD in secure Kudu cluster deployments, make sure SSSD packages are
	of version 1.16 or newer
	(see <a href="https://issues.apache.org/jira/browse/KUDU-3217">KUDU-3217</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>

	<a href="release_notes.html">Kudu Release Notes</a>
	</li>
	<li>

	<a href="quickstart.html">Quickstart Guide</a>
	</li>
	<li>

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

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

	<a href="hive_metastore.html">Using the Hive Metastore with 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="scaling_guide.html">Kudu Scaling Guide</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="metrics_reference.html">Kudu Metrics Reference</a>
	</li>
	<li>
	<span class="active-toc">Known Issues and Limitations</span>
	<ul class="sectlevel1">
	<li><a href="#_schema">Schema</a>
	<ul class="sectlevel2">
	<li><a href="#_primary_keys">Primary keys</a></li>
	<li><a href="#_columns">Columns</a></li>
	<li><a href="#_tables">Tables</a></li>
	<li><a href="#_cells_individual_values">Cells (individual values)</a></li>
	<li><a href="#_other_usage_limitations">Other usage limitations</a></li>
	</ul>
	</li>
	<li><a href="#_partitioning_limitations">Partitioning Limitations</a></li>
	<li><a href="#_cluster_management">Cluster management</a></li>
	<li><a href="#_server_management">Server management</a></li>
	<li><a href="#_scale">Scale</a></li>
	<li><a href="#_security_limitations">Security Limitations</a></li>
	<li><a href="#_other_known_issues">Other Known Issues</a></li>
	</ul>
	</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>