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| <h1>Known Issues and Limitations</h1> |
| <div class="sect1"> |
| <h2 id="_schema_and_usage_limitations"><a class="link" href="#_schema_and_usage_limitations">Schema and Usage Limitations</a></h2> |
| <div class="sectionbody"> |
| <div class="ulist"> |
| <ul> |
| <li> |
| <p>Kudu is primarily designed for analytic use cases. You are likely to encounter issues if |
| a single row contains multiple kilobytes of data.</p> |
| </li> |
| <li> |
| <p>The columns which make up the primary key must be listed first in the schema.</p> |
| </li> |
| <li> |
| <p>Columns that are part of the primary key cannot be renamed. |
| 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 |
| or rename key columns.</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>Type and nullability of existing columns cannot be changed by altering the table.</p> |
| </li> |
| <li> |
| <p>Dropping a column does not immediately reclaim space. Compaction must run first. |
| There is no way to run compaction manually, but dropping the table will reclaim the |
| space immediately.</p> |
| </li> |
| </ul> |
| </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</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> |
| </ul> |
| </div> |
| </div> |
| </div> |
| <div class="sect1"> |
| <h2 id="_replication_and_backup_limitations"><a class="link" href="#_replication_and_backup_limitations">Replication and Backup Limitations</a></h2> |
| <div class="sectionbody"> |
| <div class="ulist"> |
| <ul> |
| <li> |
| <p>Kudu does not currently include any built-in features for backup and restore. |
| Users are encouraged to use tools such as Spark or Impala to export or import |
| tables as necessary.</p> |
| </li> |
| </ul> |
| </div> |
| </div> |
| </div> |
| <div class="sect1"> |
| <h2 id="_impala_limitations"><a class="link" href="#_impala_limitations">Impala Limitations</a></h2> |
| <div class="sectionbody"> |
| <div class="ulist"> |
| <ul> |
| <li> |
| <p>Updates, inserts, and deletes via Impala are non-transactional. If a query |
| fails part of the way through, its partial effects will not be rolled back.</p> |
| </li> |
| <li> |
| <p>No timestamp and decimal type support.</p> |
| </li> |
| <li> |
| <p>The maximum parallelism of a single query is limited to the number of tablets |
| in a table. For good analytic performance, aim for 10 or more tablets per host |
| or use large tables.</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>Authorization is only available at a system-wide, coarse-grained level. Table-level, |
| column-level, and row-level authorization features are not available.</p> |
| </li> |
| <li> |
| <p>Data encryption at rest is not built in. Kudu has been reported to run correctly |
| on systems using local block device encryption (e.g. <code>dmcrypt</code>).</p> |
| </li> |
| <li> |
| <p>Kudu server Kerberos principals must follow the pattern <code>kudu/<HOST>@DEFAULT.REALM</code>. |
| Configuring an alternate Kerberos principal is not supported.</p> |
| </li> |
| <li> |
| <p>Kudu’s integration with Apache Flume does not support writing to Kudu clusters that |
| require Kerberos authentication.</p> |
| </li> |
| <li> |
| <p>Kudu client instances retrieve authentication tokens upon first contact with the |
| cluster. These tokens expire after one week. Use of a single Kudu client instance |
| for more than one week is not supported.</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 the Kudu master is configured with the <code>-log_force_fsync_all</code> option, tablet servers |
| and clients will experience frequent timeouts, and the cluster may become unusable.</p> |
| </li> |
| <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 100 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> |
| </ul> |
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| |
| <li> |
| |
| <a href="index.html">Introducing Kudu</a> |
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| <li> |
| |
| <a href="release_notes.html">Kudu Release Notes</a> |
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| <li> |
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| <a href="quickstart.html">Getting Started with Kudu</a> |
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| |
| <a href="installation.html">Installation Guide</a> |
| </li> |
| <li> |
| |
| <a href="configuration.html">Configuring Kudu</a> |
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| <li> |
| |
| <a href="kudu_impala_integration.html">Using Impala with Kudu</a> |
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| <a href="administration.html">Administering Kudu</a> |
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| <a href="troubleshooting.html">Troubleshooting Kudu</a> |
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| <a href="developing.html">Developing Applications with Kudu</a> |
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| |
| <a href="schema_design.html">Kudu Schema Design</a> |
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| |
| <a href="transaction_semantics.html">Kudu Transaction Semantics</a> |
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| <a href="background_tasks.html">Background Maintenance Tasks</a> |
| </li> |
| <li> |
| |
| <a href="configuration_reference.html">Kudu Configuration Reference</a> |
| </li> |
| <li> |
| <span class="active-toc">Known Issues and Limitations</span> |
| <ul class="sectlevel1"> |
| <li><a href="#_schema_and_usage_limitations">Schema and Usage Limitations</a></li> |
| <li><a href="#_partitioning_limitations">Partitioning Limitations</a></li> |
| <li><a href="#_replication_and_backup_limitations">Replication and Backup Limitations</a></li> |
| <li><a href="#_impala_limitations">Impala Limitations</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> |
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| <li> |
| |
| <a href="export_control.html">Export Control Notice</a> |
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