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http://git-wip-us.apache.org/repos/asf/kudu/blob/1fefa84c/docs/kudu_impala_integration.html
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-title: Using Apache Kudu with Apache Impala
-layout: default
-active_nav: docs
-last_updated: 'Last updated 2018-06-15 07:22:05 PDT'
----
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-Licensed under the Apache License, Version 2.0 (the "License");
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- http://www.apache.org/licenses/LICENSE-2.0
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-
-
-<div class="container">
- <div class="row">
- <div class="col-md-9">
-
-<h1>Using Apache Kudu with Apache Impala</h1>
- <div id="preamble">
-<div class="sectionbody">
-<div class="paragraph">
-<p>Kudu has tight integration with Apache Impala, allowing you to use Impala
-to insert, query, update, and delete data from Kudu tablets using Impala’s SQL
-syntax, as an alternative to using the <a href="installation.html#view_api">Kudu APIs</a>
-to build a custom Kudu application. In addition, you can use JDBC or ODBC to connect
-existing or new applications written in any language, framework, or business intelligence
-tool to your Kudu data, using Impala as the broker.</p>
-</div>
-</div>
-</div>
-<div class="sect1">
-<h2 id="_requirements"><a class="link" href="#_requirements">Requirements</a></h2>
-<div class="sectionbody">
-<div class="ulist">
-<ul>
-<li>
-<p>This documentation is specific to the certain versions of Impala. The syntax
-described will work only in the following releases:</p>
-<div class="ulist">
-<ul>
-<li>
-<p>The version of Impala 2.7.0 that ships with CDH 5.10. <code>SELECT VERSION()</code> will
-report <code>impalad version 2.7.0-cdh5.10.0</code>.</p>
-</li>
-<li>
-<p>Apache Impala 2.8.0 releases compiled from source. <code>SELECT VERSION()</code> will
-report <code>impalad version 2.8.0</code>.</p>
-</li>
-</ul>
-</div>
-</li>
-</ul>
-</div>
-<div class="paragraph">
-<p>Older versions of Impala 2.7 (including the special <code>IMPALA_KUDU</code> releases
-previously available) have incompatible syntax. Future versions are likely to be
-compatible with this syntax, but we recommend checking that this is the latest
-available documentation corresponding to the appropriate version you have
-installed.</p>
-</div>
-<div class="ulist">
-<ul>
-<li>
-<p>This documentation does not describe Impala installation procedures. Please
-refer to the Impala documentation and be sure that you are able to run simple
-queries against Impala tables on HDFS before proceeding.</p>
-</li>
-</ul>
-</div>
-</div>
-</div>
-<div class="sect1">
-<h2 id="_configuration"><a class="link" href="#_configuration">Configuration</a></h2>
-<div class="sectionbody">
-<div class="paragraph">
-<p>No configuration changes are required within Kudu to enable access from Impala.</p>
-</div>
-<div class="paragraph">
-<p>Although not strictly necessary, it is recommended to configure Impala with the
-locations of the Kudu Master servers:</p>
-</div>
-<div class="ulist">
-<ul>
-<li>
-<p>Set the <code>--kudu_master_hosts=<master1>[:port],<master2>[:port],<master3>[:port]</code>
-flag in the Impala service configuration. If you are using Cloudera Manager,
-please refer to the appropriate Cloudera Manager documentation to do so.</p>
-</li>
-</ul>
-</div>
-<div class="paragraph">
-<p>If this flag is not set within the Impala service, it will be necessary to manually
-provide this configuration each time you create a table by specifying the
-<code>kudu_master_addresses</code> property inside a <code>TBLPROPERTIES</code> clause.</p>
-</div>
-<div class="paragraph">
-<p>The rest of this guide assumes that the configuration has been set.</p>
-</div>
-</div>
-</div>
-<div class="sect1">
-<h2 id="_using_the_impala_shell"><a class="link" href="#_using_the_impala_shell">Using the Impala Shell</a></h2>
-<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 is only a small sub-set of Impala Shell functionality. For more details, see the
-<a href="http://www.cloudera.com/content/cloudera/en/documentation/core/latest/topics/impala_impala_shell.html">Impala Shell</a> documentation.
-</td>
-</tr>
-</table>
-</div>
-<div class="ulist">
-<ul>
-<li>
-<p>Start Impala Shell using the <code>impala-shell</code> command. By default, <code>impala-shell</code>
-attempts to connect to the Impala daemon on <code>localhost</code> on port 21000. To connect
-to a different host,, use the <code>-i <host:port></code> option. To automatically connect to
-a specific Impala database, use the <code>-d <database></code> option. For instance, if all your
-Kudu tables are in Impala in the database <code>impala_kudu</code>, use <code>-d impala_kudu</code> to use
-this database.</p>
-</li>
-<li>
-<p>To quit the Impala Shell, use the following command: <code>quit;</code></p>
-</li>
-</ul>
-</div>
-<div class="sect2">
-<h3 id="_internal_and_external_impala_tables"><a class="link" href="#_internal_and_external_impala_tables">Internal and External Impala Tables</a></h3>
-<div class="paragraph">
-<p>When creating a new Kudu table using Impala, you can create the table as an internal
-table or an external table.</p>
-</div>
-<div class="dlist">
-<dl>
-<dt class="hdlist1">Internal</dt>
-<dd>
-<p>An internal table is managed by Impala, and when you drop it from Impala,
-the data and the table truly are dropped. When you create a new table using Impala,
-it is generally a internal table.</p>
-</dd>
-<dt class="hdlist1">External</dt>
-<dd>
-<p>An external table (created by <code>CREATE EXTERNAL TABLE</code>) is not managed by
-Impala, and dropping such a table does not drop the table from its source location
-(here, Kudu). Instead, it only removes the mapping between Impala and Kudu. This is
-the mode used in the syntax provided by Kudu for mapping an existing table to Impala.</p>
-</dd>
-</dl>
-</div>
-<div class="paragraph">
-<p>See the
-<a href="http://www.cloudera.com/content/cloudera/en/documentation/core/latest/topics/impala_tables.html">Impala documentation</a>
-for more information about internal and external tables.</p>
-</div>
-</div>
-<div class="sect2">
-<h3 id="_querying_an_existing_kudu_table_in_impala"><a class="link" href="#_querying_an_existing_kudu_table_in_impala">Querying an Existing Kudu Table In Impala</a></h3>
-<div class="paragraph">
-<p>Tables created through the Kudu API or other integrations such as Apache Spark
-are not automatically visible in Impala. To query them, you must first create
-an external table within Impala to map the Kudu table into an Impala database:</p>
-</div>
-<div class="listingblock">
-<div class="content">
-<pre class="highlight"><code class="language-sql" data-lang="sql">CREATE EXTERNAL TABLE my_mapping_table
-STORED AS KUDU
-TBLPROPERTIES (
- 'kudu.table_name' = 'my_kudu_table'
-);</code></pre>
-</div>
-</div>
-</div>
-<div class="sect2">
-<h3 id="kudu_impala_create_table"><a class="link" href="#kudu_impala_create_table">Creating a New Kudu Table From Impala</a></h3>
-<div class="paragraph">
-<p>Creating a new table in Kudu from Impala is similar to mapping an existing Kudu table
-to an Impala table, except that you need to specify the schema and partitioning
-information yourself.</p>
-</div>
-<div class="paragraph">
-<p>Use the following example as a guideline. Impala first creates the table, then creates
-the mapping.</p>
-</div>
-<div class="listingblock">
-<div class="content">
-<pre class="highlight"><code class="language-sql" data-lang="sql">CREATE TABLE my_first_table
-(
- id BIGINT,
- name STRING,
- PRIMARY KEY(id)
-)
-PARTITION BY HASH PARTITIONS 16
-STORED AS KUDU;</code></pre>
-</div>
-</div>
-<div class="paragraph">
-<p>In the <code>CREATE TABLE</code> statement, the columns that comprise the primary key must
-be listed first. Additionally, primary key columns are implicitly marked <code>NOT NULL</code>.</p>
-</div>
-<div class="paragraph">
-<p>When creating a new Kudu table, you are required to specify a distribution scheme.
-See <a href="#partitioning_tables">Partitioning Tables</a>. The table creation example above is distributed into
-16 partitions by hashing the <code>id</code> column, for simplicity. See
-<a href="#partitioning_rules_of_thumb">Partitioning Rules of Thumb</a> for guidelines on partitioning.</p>
-</div>
-<div class="sect3">
-<h4 id="_code_create_table_as_select_code"><a class="link" href="#_code_create_table_as_select_code"><code>CREATE TABLE AS SELECT</code></a></h4>
-<div class="paragraph">
-<p>You can create a table by querying any other table or tables in Impala, using a <code>CREATE
-TABLE …​ AS SELECT</code> statement. The following example imports all rows from an existing table
-<code>old_table</code> into a Kudu table <code>new_table</code>. The names and types of columns in <code>new_table</code>
-will determined from the columns in the result set of the <code>SELECT</code> statement. Note that you must
-additionally specify the primary key and partitioning.</p>
-</div>
-<div class="listingblock">
-<div class="content">
-<pre class="highlight"><code class="language-sql" data-lang="sql">CREATE TABLE new_table
-PRIMARY KEY (ts, name)
-PARTITION BY HASH(name) PARTITIONS 8
-STORED AS KUDU
-AS SELECT ts, name, value FROM old_table;</code></pre>
-</div>
-</div>
-</div>
-<div class="sect3">
-<h4 id="_specifying_tablet_partitioning"><a class="link" href="#_specifying_tablet_partitioning">Specifying Tablet Partitioning</a></h4>
-<div class="paragraph">
-<p>Tables are divided into tablets which are each served by one or more tablet
-servers. Ideally, tablets should split a table’s data relatively equally. Kudu currently
-has no mechanism for automatically (or manually) splitting a pre-existing tablet.
-Until this feature has been implemented, <strong>you must specify your partitioning when
-creating a table</strong>. When designing your table schema, consider primary keys that will allow you to
-split your table into partitions which grow at similar rates. You can designate
-partitions using a <code>PARTITION BY</code> clause when creating a table using Impala:</p>
-</div>
-<div class="admonitionblock note">
-<table>
-<tr>
-<td class="icon">
-<i class="fa icon-note" title="Note"></i>
-</td>
-<td class="content">
-Impala keywords, such as <code>group</code>, are enclosed by back-tick characters when
-they are not used in their keyword sense.
-</td>
-</tr>
-</table>
-</div>
-<div class="listingblock">
-<div class="content">
-<pre class="highlight"><code class="language-sql" data-lang="sql">CREATE TABLE cust_behavior (
- _id BIGINT PRIMARY KEY,
- salary STRING,
- edu_level INT,
- usergender STRING,
- `group` STRING,
- city STRING,
- postcode STRING,
- last_purchase_price FLOAT,
- last_purchase_date BIGINT,
- category STRING,
- sku STRING,
- rating INT,
- fulfilled_date BIGINT
-)
-PARTITION BY RANGE (_id)
-(
- PARTITION VALUES < 1439560049342,
- PARTITION 1439560049342 <= VALUES < 1439566253755,
- PARTITION 1439566253755 <= VALUES < 1439572458168,
- PARTITION 1439572458168 <= VALUES < 1439578662581,
- PARTITION 1439578662581 <= VALUES < 1439584866994,
- PARTITION 1439584866994 <= VALUES < 1439591071407,
- PARTITION 1439591071407 <= VALUES
-)
-STORED AS KUDU;</code></pre>
-</div>
-</div>
-<div class="paragraph">
-<p>If you have multiple primary key columns, you can specify partition bounds
-using tuple syntax: <code>('va',1), ('ab',2)</code>. The expression must be valid JSON.</p>
-</div>
-</div>
-<div class="sect3">
-<h4 id="_impala_databases_and_kudu"><a class="link" href="#_impala_databases_and_kudu">Impala Databases and Kudu</a></h4>
-<div class="paragraph">
-<p>Every Impala table is contained within a namespace called a <em>database</em>. The default
-database is called <code>default</code>, and users may create and drop additional databases
-as desired.</p>
-</div>
-<div class="paragraph">
-<p>When a managed Kudu table is created from within Impala, the corresponding
-Kudu table will be named <code>my_database::table_name</code>.</p>
-</div>
-</div>
-<div class="sect3">
-<h4 id="_impala_keywords_not_supported_for_kudu_tables"><a class="link" href="#_impala_keywords_not_supported_for_kudu_tables">Impala Keywords Not Supported for Kudu Tables</a></h4>
-<div class="paragraph">
-<p>The following Impala keywords are not supported when creating Kudu tables:
-- <code>PARTITIONED</code>
-- <code>LOCATION</code>
-- <code>ROWFORMAT</code></p>
-</div>
-</div>
-</div>
-<div class="sect2">
-<h3 id="_optimizing_performance_for_evaluating_sql_predicates"><a class="link" href="#_optimizing_performance_for_evaluating_sql_predicates">Optimizing Performance for Evaluating SQL Predicates</a></h3>
-<div class="paragraph">
-<p>If the <code>WHERE</code> clause of your query includes comparisons with the operators
-<code>=</code>, <code><=</code>, '\<', '\>', <code>>=</code>, <code>BETWEEN</code>, or <code>IN</code>, Kudu evaluates the condition directly
-and only returns the relevant results. This provides optimum performance, because Kudu
-only returns the relevant results to Impala. For predicates <code>!=</code>, <code>LIKE</code>, or any other
-predicate type supported by Impala, Kudu does not evaluate the predicates directly, but
-returns all results to Impala and relies on Impala to evaluate the remaining predicates and
-filter the results accordingly. This may cause differences in performance, depending
-on the delta of the result set before and after evaluating the <code>WHERE</code> clause.</p>
-</div>
-</div>
-<div class="sect2">
-<h3 id="partitioning_tables"><a class="link" href="#partitioning_tables">Partitioning Tables</a></h3>
-<div class="paragraph">
-<p>Tables are partitioned into tablets according to a partition schema on the primary
-key columns. Each tablet is served by at least one tablet server. Ideally, a table
-should be split into tablets that are distributed across a number of tablet servers
-to maximize parallel operations. The details of the partitioning schema you use
-will depend entirely on the type of data you store and how you access it. For a full
-discussion of schema design in Kudu, see <a href="schema_design.html">Schema Design</a>.</p>
-</div>
-<div class="paragraph">
-<p>Kudu currently has no mechanism for splitting or merging tablets after the table has
-been created. You must provide a partition schema for your table when you create it.
-When designing your tables, consider using primary keys that will allow you to partition
-your table into tablets which grow at similar rates.</p>
-</div>
-<div class="paragraph">
-<p>You can partition your table using Impala’s <code>PARTITION BY</code> keyword, which
-supports distribution by <code>RANGE</code> or <code>HASH</code>. The partition scheme can contain zero
-or more <code>HASH</code> definitions, followed by an optional <code>RANGE</code> definition. The <code>RANGE</code>
-definition can refer to one or more primary key columns.
-Examples of <a href="#basic_partitioning">basic</a> and <a href="#advanced_partitioning">advanced</a>
-partitioning are shown below.</p>
-</div>
-<div class="sect3">
-<h4 id="basic_partitioning"><a class="link" href="#basic_partitioning">Basic Partitioning</a></h4>
-<div class="paragraph">
-<div class="title"><code>PARTITION BY RANGE</code></div>
-<p>You can specify range partitions for one or more primary key columns.
-Range partitioning in Kudu allows splitting a table based based on
-specific values or ranges of values of the chosen partition keys. This allows
-you to balance parallelism in writes with scan efficiency.</p>
-</div>
-<div class="paragraph">
-<p>Suppose you have a table that has columns <code>state</code>, <code>name</code>, and <code>purchase_count</code>. The
-following example creates 50 tablets, one per US state.</p>
-</div>
-<div class="admonitionblock note">
-<table>
-<tr>
-<td class="icon">
-<i class="fa icon-note" title="Note"></i>
-</td>
-<td class="content">
-<div class="title">Monotonically Increasing Values</div>
-<div class="paragraph">
-<p>If you partition by range on a column whose values are monotonically increasing,
-the last tablet will grow much larger than the others. Additionally, all data
-being inserted will be written to a single tablet at a time, limiting the scalability
-of data ingest. In that case, consider distributing by <code>HASH</code> instead of, or in
-addition to, <code>RANGE</code>.</p>
-</div>
-</td>
-</tr>
-</table>
-</div>
-<div class="listingblock">
-<div class="content">
-<pre class="highlight"><code class="language-sql" data-lang="sql">CREATE TABLE customers (
- state STRING,
- name STRING,
- purchase_count int,
- PRIMARY KEY (state, name)
-)
-PARTITION BY RANGE (state)
-(
- PARTITION VALUE = 'al',
- PARTITION VALUE = 'ak',
- PARTITION VALUE = 'ar',
- -- ... etc ...
- PARTITION VALUE = 'wv',
- PARTITION VALUE = 'wy'
-)
-STORED AS KUDU;</code></pre>
-</div>
-</div>
-<div id="distribute_by_hash" class="paragraph">
-<div class="title"><code>PARTITION BY HASH</code></div>
-<p>Instead of distributing by an explicit range, or in combination with range distribution,
-you can distribute into a specific number of 'buckets' by hash. You specify the primary
-key columns you want to partition by, and the number of buckets you want to use. Rows are
-distributed by hashing the specified key columns. Assuming that the values being
-hashed do not themselves exhibit significant skew, this will serve to distribute
-the data evenly across buckets.</p>
-</div>
-<div class="paragraph">
-<p>You can specify multiple definitions, and you can specify definitions which
-use compound primary keys. However, one column cannot be mentioned in multiple hash
-definitions. Consider two columns, <code>a</code> and <code>b</code>:
-* <span class="icon green"><i class="fa fa-check fa-pro"></i></span> <code>HASH(a)</code>, <code>HASH(b)</code>
-* <span class="icon green"><i class="fa fa-check fa-pro"></i></span> <code>HASH(a,b)</code>
-* <span class="icon red"><i class="fa fa-times fa-pro"></i></span> <code>HASH(a), HASH(a,b)</code></p>
-</div>
-<div class="admonitionblock note">
-<table>
-<tr>
-<td class="icon">
-<i class="fa icon-note" title="Note"></i>
-</td>
-<td class="content">
-<code>PARTITION BY HASH</code> with no column specified is a shortcut to create the desired
-number of buckets by hashing all primary key columns.
-</td>
-</tr>
-</table>
-</div>
-<div class="paragraph">
-<p>Hash partitioning is a reasonable approach if primary key values are evenly
-distributed in their domain and no data skew is apparent, such as timestamps or
-serial IDs.</p>
-</div>
-<div class="paragraph">
-<p>The following example creates 16 tablets by hashing the <code>id</code> and <code>sku</code> columns. This spreads
-writes across all 16 tablets. In this example, a query for a range of <code>sku</code> values
-is likely to need to read all 16 tablets, so this may not be the optimum schema for
-this table. See <a href="#advanced_partitioning">Advanced Partitioning</a> for an extended example.</p>
-</div>
-<div class="listingblock">
-<div class="content">
-<pre class="highlight"><code class="language-sql" data-lang="sql">CREATE TABLE cust_behavior (
- id BIGINT,
- sku STRING,
- salary STRING,
- edu_level INT,
- usergender STRING,
- `group` STRING,
- city STRING,
- postcode STRING,
- last_purchase_price FLOAT,
- last_purchase_date BIGINT,
- category STRING,
- rating INT,
- fulfilled_date BIGINT,
- PRIMARY KEY (id, sku)
-)
-PARTITION BY HASH PARTITIONS 16
-STORED AS KUDU;</code></pre>
-</div>
-</div>
-</div>
-<div class="sect3">
-<h4 id="advanced_partitioning"><a class="link" href="#advanced_partitioning">Advanced Partitioning</a></h4>
-<div class="paragraph">
-<p>You can combine <code>HASH</code> and <code>RANGE</code> partitioning to create more complex partition schemas.
-You can specify zero or more <code>HASH</code> definitions, followed by zero or one <code>RANGE</code> definitions.
-Each definition can encompass one or more columns. While enumerating every possible distribution
-schema is out of the scope of this document, a few examples illustrate some of the
-possibilities.</p>
-</div>
-</div>
-<div class="sect3">
-<h4 id="_code_partition_by_hash_code_and_code_range_code"><a class="link" href="#_code_partition_by_hash_code_and_code_range_code"><code>PARTITION BY HASH</code> and <code>RANGE</code></a></h4>
-<div class="paragraph">
-<p>Consider the <a href="#distribute_by_hash">simple hashing</a> example above, If you often query for a range of <code>sku</code>
-values, you can optimize the example by combining hash partitioning with range partitioning.</p>
-</div>
-<div class="paragraph">
-<p>The following example still creates 16 tablets, by first hashing the <code>id</code> column into 4
-buckets, and then applying range partitioning to split each bucket into four tablets,
-based upon the value of the <code>sku</code> string. Writes are spread across at least four tablets
-(and possibly up to 16). When you query for a contiguous range of <code>sku</code> values, you have a
-good chance of only needing to read from a quarter of the tablets to fulfill the query.</p>
-</div>
-<div class="admonitionblock note">
-<table>
-<tr>
-<td class="icon">
-<i class="fa icon-note" title="Note"></i>
-</td>
-<td class="content">
-By default, the entire primary key is hashed when you use <code>PARTITION BY HASH</code>.
-To hash on only part of the primary key, specify it by using syntax like <code>PARTITION
-BY HASH (id, sku)</code>.
-</td>
-</tr>
-</table>
-</div>
-<div class="listingblock">
-<div class="content">
-<pre class="highlight"><code class="language-sql" data-lang="sql">CREATE TABLE cust_behavior (
- id BIGINT,
- sku STRING,
- salary STRING,
- edu_level INT,
- usergender STRING,
- `group` STRING,
- city STRING,
- postcode STRING,
- last_purchase_price FLOAT,
- last_purchase_date BIGINT,
- category STRING,
- rating INT,
- fulfilled_date BIGINT,
- PRIMARY KEY (id, sku)
-)
-PARTITION BY HASH (id) PARTITIONS 4,
-RANGE (sku)
-(
- PARTITION VALUES < 'g',
- PARTITION 'g' <= VALUES < 'o',
- PARTITION 'o' <= VALUES < 'u',
- PARTITION 'u' <= VALUES
-)
-STORED AS KUDU;</code></pre>
-</div>
-</div>
-<div class="paragraph">
-<div class="title">Multiple <code>PARTITION BY HASH</code> Definitions</div>
-<p>Again expanding the example above, suppose that the query pattern will be unpredictable,
-but you want to ensure that writes are spread across a large number of tablets
-You can achieve maximum distribution across the entire primary key by hashing on
-both primary key columns.</p>
-</div>
-<div class="listingblock">
-<div class="content">
-<pre class="highlight"><code class="language-sql" data-lang="sql">CREATE TABLE cust_behavior (
- id BIGINT,
- sku STRING,
- salary STRING,
- edu_level INT,
- usergender STRING,
- `group` STRING,
- city STRING,
- postcode STRING,
- last_purchase_price FLOAT,
- last_purchase_date BIGINT,
- category STRING,
- rating INT,
- fulfilled_date BIGINT,
- PRIMARY KEY (id, sku)
-)
-PARTITION BY HASH (id) PARTITIONS 4,
- HASH (sku) PARTITIONS 4
-STORED AS KUDU;</code></pre>
-</div>
-</div>
-<div class="paragraph">
-<p>The example creates 16 partitions. You could also use <code>HASH (id, sku) PARTITIONS 16</code>.
-However, a scan for <code>sku</code> values would almost always impact all 16 partitions, rather
-than possibly being limited to 4.</p>
-</div>
-<div class="paragraph">
-<div class="title">Non-Covering Range Partitions</div>
-<p>Kudu 1.0 and higher supports the use of non-covering range partitions,
-which address scenarios like the following:</p>
-</div>
-<div class="ulist">
-<ul>
-<li>
-<p>Without non-covering range partitions, in the case of time-series data or other
-schemas which need to account for constantly-increasing primary keys, tablets
-serving old data will be relatively fixed in size, while tablets receiving new
-data will grow without bounds.</p>
-</li>
-<li>
-<p>In cases where you want to partition data based on its category, such as sales
-region or product type, without non-covering range partitions you must know all
-of the partitions ahead of time or manually recreate your table if partitions
-need to be added or removed, such as the introduction or elimination of a product
-type.</p>
-</li>
-</ul>
-</div>
-<div class="paragraph">
-<p>Non-covering range partitions have some caveats. Be sure to read the
-link:/docs/schema_design.html [Schema Design guide].</p>
-</div>
-<div class="paragraph">
-<p>This example creates a tablet per year (5 tablets total), for storing log data.
-The table only accepts data from 2012 to 2016. Keys outside of these
-ranges will be rejected.</p>
-</div>
-<div class="listingblock">
-<div class="content">
-<pre class="highlight"><code class="language-sql" data-lang="sql">CREATE TABLE sales_by_year (
- year INT, sale_id INT, amount INT,
- PRIMARY KEY (sale_id, year)
-)
-PARTITION BY RANGE (year) (
- PARTITION VALUE = 2012,
- PARTITION VALUE = 2013,
- PARTITION VALUE = 2014,
- PARTITION VALUE = 2015,
- PARTITION VALUE = 2016
-)
-STORED AS KUDU;</code></pre>
-</div>
-</div>
-<div class="paragraph">
-<p>When records start coming in for 2017, they will be rejected. At that point, the <code>2017</code>
-range should be added as follows:</p>
-</div>
-<div class="listingblock">
-<div class="content">
-<pre class="highlight"><code class="language-sql" data-lang="sql">ALTER TABLE sales_by_year ADD RANGE PARTITION VALUE = 2017;</code></pre>
-</div>
-</div>
-<div class="paragraph">
-<p>In use cases where a rolling window of data retention is required, range partitions
-may also be dropped. For example, if data from 2012 should no longer be retained,
-it may be deleted in bulk:</p>
-</div>
-<div class="listingblock">
-<div class="content">
-<pre class="highlight"><code class="language-sql" data-lang="sql">ALTER TABLE sales_by_year DROP RANGE PARTITION VALUE = 2012;</code></pre>
-</div>
-</div>
-<div class="paragraph">
-<p>Note that, just like dropping a table, this irrecoverably deletes all data
-stored in the dropped partition.</p>
-</div>
-</div>
-<div class="sect3">
-<h4 id="partitioning_rules_of_thumb"><a class="link" href="#partitioning_rules_of_thumb">Partitioning Rules of Thumb</a></h4>
-<div class="ulist">
-<ul>
-<li>
-<p>For large tables, such as fact tables, aim for as many tablets as you have
-cores in the cluster.</p>
-</li>
-<li>
-<p>For small tables, such as dimension tables, ensure that each tablet is at
-least 1 GB in size.</p>
-</li>
-</ul>
-</div>
-<div class="paragraph">
-<p>In general, be mindful the number of tablets limits the parallelism of reads,
-in the current implementation. Increasing the number of tablets significantly
-beyond the number of cores is likely to have diminishing returns.</p>
-</div>
-</div>
-</div>
-<div class="sect2">
-<h3 id="_inserting_data_into_kudu_tables"><a class="link" href="#_inserting_data_into_kudu_tables">Inserting Data Into Kudu Tables</a></h3>
-<div class="paragraph">
-<p>Impala allows you to use standard SQL syntax to insert data into Kudu.</p>
-</div>
-<div class="sect3">
-<h4 id="_inserting_single_values"><a class="link" href="#_inserting_single_values">Inserting Single Values</a></h4>
-<div class="paragraph">
-<p>This example inserts a single row.</p>
-</div>
-<div class="listingblock">
-<div class="content">
-<pre class="highlight"><code class="language-sql" data-lang="sql">INSERT INTO my_first_table VALUES (99, "sarah");</code></pre>
-</div>
-</div>
-<div class="paragraph">
-<p>This example inserts three rows using a single statement.</p>
-</div>
-<div class="listingblock">
-<div class="content">
-<pre class="highlight"><code class="language-sql" data-lang="sql">INSERT INTO my_first_table VALUES (1, "john"), (2, "jane"), (3, "jim");</code></pre>
-</div>
-</div>
-</div>
-<div class="sect3">
-<h4 id="kudu_impala_insert_bulk"><a class="link" href="#kudu_impala_insert_bulk">Inserting In Bulk</a></h4>
-<div class="paragraph">
-<p>When inserting in bulk, there are at least three common choices. Each may have advantages
-and disadvantages, depending on your data and circumstances.</p>
-</div>
-<div class="dlist">
-<dl>
-<dt class="hdlist1">Multiple single <code>INSERT</code> statements</dt>
-<dd>
-<p>This approach has the advantage of being easy to
-understand and implement. This approach is likely to be inefficient because Impala
-has a high query start-up cost compared to Kudu’s insertion performance. This will
-lead to relatively high latency and poor throughput.</p>
-</dd>
-<dt class="hdlist1">Single <code>INSERT</code> statement with multiple <code>VALUES</code></dt>
-<dd>
-<p>If you include more
-than 1024 <code>VALUES</code> statements, Impala batches them into groups of 1024 (or the value
-of <code>batch_size</code>) before sending the requests to Kudu. This approach may perform
-slightly better than multiple sequential <code>INSERT</code> statements by amortizing the query start-up
-penalties on the Impala side. To set the batch size for the current Impala
-Shell session, use the following syntax: <code>set batch_size=10000;</code></p>
-<div class="admonitionblock note">
-<table>
-<tr>
-<td class="icon">
-<i class="fa icon-note" title="Note"></i>
-</td>
-<td class="content">
-Increasing the Impala batch size causes Impala to use more memory. You should
-verify the impact on your cluster and tune accordingly.
-</td>
-</tr>
-</table>
-</div>
-</dd>
-<dt class="hdlist1">Batch Insert</dt>
-<dd>
-<p>The approach that usually performs best, from the standpoint of
-both Impala and Kudu, is usually to import the data using a <code>SELECT FROM</code> statement
-in Impala.</p>
-<div class="olist arabic">
-<ol class="arabic">
-<li>
-<p>If your data is not already in Impala, one strategy is to
-<a href="http://www.cloudera.com/content/cloudera/en/documentation/core/latest/topics/impala_txtfile.html">import it from a text file</a>,
-such as a TSV or CSV file.</p>
-</li>
-<li>
-<p><a href="#kudu_impala_create_table">Create the Kudu table</a>, being mindful that the columns
-designated as primary keys cannot have null values.</p>
-</li>
-<li>
-<p>Insert values into the Kudu table by querying the table containing the original
-data, as in the following example:</p>
-<div class="listingblock">
-<div class="content">
-<pre class="highlight"><code class="language-sql" data-lang="sql">INSERT INTO my_kudu_table
- SELECT * FROM legacy_data_import_table;</code></pre>
-</div>
-</div>
-</li>
-</ol>
-</div>
-</dd>
-<dt class="hdlist1">Ingest using the C++ or Java API</dt>
-<dd>
-<p>In many cases, the appropriate ingest path is to
-use the C++ or Java API to insert directly into Kudu tables. Unlike other Impala tables,
-data inserted into Kudu tables via the API becomes available for query in Impala without
-the need for any <code>INVALIDATE METADATA</code> statements or other statements needed for other
-Impala storage types.</p>
-</dd>
-</dl>
-</div>
-</div>
-<div class="sect3">
-<h4 id="insert_ignore"><a class="link" href="#insert_ignore"><code>INSERT</code> and Primary Key Uniqueness Violations</a></h4>
-<div class="paragraph">
-<p>In most relational databases, if you try to insert a row that has already been inserted, the insertion
-will fail because the primary key would be duplicated. See <a href="#impala_insertion_caveat">Failures During <code>INSERT</code>, <code>UPDATE</code>, and <code>DELETE</code> Operations</a>.
-Impala, however, will not fail the query. Instead, it will generate a warning, but continue
-to execute the remainder of the insert statement.</p>
-</div>
-<div class="paragraph">
-<p>If the inserted rows are meant to replace existing rows, <code>UPSERT</code> may be used instead of <code>INSERT</code>.</p>
-</div>
-<div class="listingblock">
-<div class="content">
-<pre class="highlight"><code class="language-sql" data-lang="sql">INSERT INTO my_first_table VALUES (99, "sarah");
-UPSERT INTO my_first_table VALUES (99, "zoe");
--- the current value of the row is 'zoe'</code></pre>
-</div>
-</div>
-</div>
-</div>
-<div class="sect2">
-<h3 id="_updating_a_row"><a class="link" href="#_updating_a_row">Updating a Row</a></h3>
-<div class="listingblock">
-<div class="content">
-<pre class="highlight"><code class="language-sql" data-lang="sql">UPDATE my_first_table SET name="bob" where id = 3;</code></pre>
-</div>
-</div>
-<div class="admonitionblock important">
-<table>
-<tr>
-<td class="icon">
-<i class="fa icon-important" title="Important"></i>
-</td>
-<td class="content">
-The <code>UPDATE</code> statement only works in Impala when the target table is in
-Kudu.
-</td>
-</tr>
-</table>
-</div>
-<div class="sect3">
-<h4 id="_updating_in_bulk"><a class="link" href="#_updating_in_bulk">Updating In Bulk</a></h4>
-<div class="paragraph">
-<p>You can update in bulk using the same approaches outlined in
-<a href="#kudu_impala_insert_bulk">Inserting In Bulk</a>.</p>
-</div>
-<div class="listingblock">
-<div class="content">
-<pre class="highlight"><code class="language-sql" data-lang="sql">UPDATE my_first_table SET name="bob" where age > 10;</code></pre>
-</div>
-</div>
-</div>
-</div>
-<div class="sect2">
-<h3 id="_deleting_a_row"><a class="link" href="#_deleting_a_row">Deleting a Row</a></h3>
-<div class="listingblock">
-<div class="content">
-<pre class="highlight"><code class="language-sql" data-lang="sql">DELETE FROM my_first_table WHERE id < 3;</code></pre>
-</div>
-</div>
-<div class="paragraph">
-<p>You can also delete using more complex syntax. A comma in the <code>FROM</code> sub-clause is
-one way that Impala specifies a join query. For more information about Impala joins,
-see <a href="http://www.cloudera.com/content/cloudera/en/documentation/core/latest/topics/impala_joins.html" class="bare">http://www.cloudera.com/content/cloudera/en/documentation/core/latest/topics/impala_joins.html</a>.</p>
-</div>
-<div class="listingblock">
-<div class="content">
-<pre class="highlight"><code class="language-sql" data-lang="sql">DELETE c FROM my_second_table c, stock_symbols s WHERE c.name = s.symbol;</code></pre>
-</div>
-</div>
-<div class="admonitionblock important">
-<table>
-<tr>
-<td class="icon">
-<i class="fa icon-important" title="Important"></i>
-</td>
-<td class="content">
-The <code>DELETE</code> statement only works in Impala when the target table is in
-Kudu.
-</td>
-</tr>
-</table>
-</div>
-<div class="sect3">
-<h4 id="_deleting_in_bulk"><a class="link" href="#_deleting_in_bulk">Deleting In Bulk</a></h4>
-<div class="paragraph">
-<p>You can delete in bulk using the same approaches outlined in
-<a href="#kudu_impala_insert_bulk">Inserting In Bulk</a>.</p>
-</div>
-<div class="listingblock">
-<div class="content">
-<pre class="highlight"><code class="language-sql" data-lang="sql">DELETE FROM my_first_table WHERE id < 3;</code></pre>
-</div>
-</div>
-</div>
-</div>
-<div class="sect2">
-<h3 id="impala_insertion_caveat"><a class="link" href="#impala_insertion_caveat">Failures During <code>INSERT</code>, <code>UPDATE</code>, and <code>DELETE</code> Operations</a></h3>
-<div class="paragraph">
-<p><code>INSERT</code>, <code>UPDATE</code>, and <code>DELETE</code> statements cannot be considered transactional as
-a whole. If one of these operations fails part of the way through, the keys may
-have already been created (in the case of <code>INSERT</code>) or the records may have already
-been modified or removed by another process (in the case of <code>UPDATE</code> or <code>DELETE</code>).
-You should design your application with this in mind.</p>
-</div>
-</div>
-<div class="sect2">
-<h3 id="_altering_table_properties"><a class="link" href="#_altering_table_properties">Altering Table Properties</a></h3>
-<div class="paragraph">
-<p>You can change Impala’s metadata relating to a given Kudu table by altering the table’s
-properties. These properties include the table name, the list of Kudu master addresses,
-and whether the table is managed by Impala (internal) or externally.</p>
-</div>
-<div class="listingblock">
-<div class="title">Rename an Impala Mapping Table</div>
-<div class="content">
-<pre class="highlight"><code class="language-sql" data-lang="sql">ALTER TABLE my_table RENAME TO my_new_table;</code></pre>
-</div>
-</div>
-<div class="admonitionblock note">
-<table>
-<tr>
-<td class="icon">
-<i class="fa icon-note" title="Note"></i>
-</td>
-<td class="content">
-Renaming a table using the <code>ALTER TABLE …​ RENAME</code> statement only renames
-the Impala mapping table, regardless of whether the table is an internal or external
-table. This avoids disruption to other applications that may be accessing the
-underlying Kudu table.
-</td>
-</tr>
-</table>
-</div>
-<div class="paragraph">
-<div class="title">Rename the underlying Kudu table for an internal table</div>
-<p>If a table is an internal table, the underlying Kudu table may be renamed by
-changing the <code>kudu.table_name</code> property:</p>
-</div>
-<div class="listingblock">
-<div class="content">
-<pre class="highlight"><code class="language-sql" data-lang="sql">ALTER TABLE my_internal_table
-SET TBLPROPERTIES('kudu.table_name' = 'new_name')</code></pre>
-</div>
-</div>
-<div class="paragraph">
-<div class="title">Remapping an external table to a different Kudu table</div>
-<p>If another application has renamed a Kudu table under Impala, it is possible to
-re-map an external table to point to a different Kudu table name.</p>
-</div>
-<div class="listingblock">
-<div class="content">
-<pre class="highlight"><code class="language-sql" data-lang="sql">ALTER TABLE my_external_table_
-SET TBLPROPERTIES('kudu.table_name' = 'some_other_kudu_table')</code></pre>
-</div>
-</div>
-<div class="listingblock">
-<div class="title">Change the Kudu Master Address</div>
-<div class="content">
-<pre class="highlight"><code class="language-sql" data-lang="sql">ALTER TABLE my_table
-SET TBLPROPERTIES('kudu.master_addresses' = 'kudu-new-master.example.com:7051');</code></pre>
-</div>
-</div>
-<div class="listingblock">
-<div class="title">Change an Internally-Managed Table to External</div>
-<div class="content">
-<pre class="highlight"><code class="language-sql" data-lang="sql">ALTER TABLE my_table SET TBLPROPERTIES('EXTERNAL' = 'TRUE');</code></pre>
-</div>
-</div>
-</div>
-<div class="sect2">
-<h3 id="_dropping_a_kudu_table_using_impala"><a class="link" href="#_dropping_a_kudu_table_using_impala">Dropping a Kudu Table Using Impala</a></h3>
-<div class="paragraph">
-<p>If the table was created as an internal table in Impala, using <code>CREATE TABLE</code>, the
-standard <code>DROP TABLE</code> syntax drops the underlying Kudu table and all its data. If
-the table was created as an external table, using <code>CREATE EXTERNAL TABLE</code>, the mapping
-between Impala and Kudu is dropped, but the Kudu table is left intact, with all its
-data.</p>
-</div>
-<div class="listingblock">
-<div class="content">
-<pre class="highlight"><code class="language-sql" data-lang="sql">DROP TABLE my_first_table;</code></pre>
-</div>
-</div>
-</div>
-</div>
-</div>
-<div class="sect1">
-<h2 id="_what_s_next"><a class="link" href="#_what_s_next">What’s Next?</a></h2>
-<div class="sectionbody">
-<div class="paragraph">
-<p>The examples above have only explored a fraction of what you can do with Impala Shell.</p>
-</div>
-<div class="ulist">
-<ul>
-<li>
-<p>Learn about the <a href="http://impala.io">Impala project</a>.</p>
-</li>
-<li>
-<p>Read the <a href="http://www.cloudera.com/content/www/en-us/documentation/enterprise/latest/topics/impala.html">Impala documentation</a>.</p>
-</li>
-<li>
-<p>View the <a href="http://www.cloudera.com/content/www/en-us/documentation/enterprise/latest/topics/impala_langref.html">Impala SQL reference</a>.</p>
-</li>
-<li>
-<p>Read about Impala internals or learn how to contribute to Impala on the <a href="https://github.com/cloudera/Impala/wiki">Impala Wiki</a>.</p>
-</li>
-<li>
-<p>Read about the native <a href="installation.html#view_api">Kudu APIs</a>.</p>
-</li>
-</ul>
-</div>
-<div class="sect2">
-<h3 id="_known_issues_and_limitations"><a class="link" href="#_known_issues_and_limitations">Known Issues and Limitations</a></h3>
-<div class="ulist">
-<ul>
-<li>
-<p>Kudu tables with a name containing upper case or non-ascii characters must be
-assigned an alternate name when used as an external table in Impala.</p>
-</li>
-<li>
-<p>Kudu tables with a column name containing upper case or non-ascii characters
-may not be used as an external table in Impala. Columns may be renamed in Kudu
-to work around this issue.</p>
-</li>
-<li>
-<p>When creating a Kudu table, the <code>CREATE TABLE</code> statement must include the
-primary key columns before other columns, in primary key order.</p>
-</li>
-<li>
-<p>Impala can not create Kudu tables with <code>VARCHAR</code> or nested-typed columns.</p>
-</li>
-<li>
-<p>Impala cannot update values in primary key columns.</p>
-</li>
-<li>
-<p><code>!=</code> and <code>LIKE</code> predicates are not pushed to Kudu, and
-instead will be evaluated by the Impala scan node. This may decrease performance
-relative to other types of predicates.</p>
-</li>
-<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>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
-for large tables.</p>
-</li>
-</ul>
-</div>
-</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">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>
-<span class="active-toc">Using Impala with Kudu</span>
- <ul class="sectlevel1">
-<li><a href="#_requirements">Requirements</a></li>
-<li><a href="#_configuration">Configuration</a></li>
-<li><a href="#_using_the_impala_shell">Using the Impala Shell</a>
-<ul class="sectlevel2">
-<li><a href="#_internal_and_external_impala_tables">Internal and External Impala Tables</a></li>
-<li><a href="#_querying_an_existing_kudu_table_in_impala">Querying an Existing Kudu Table In Impala</a></li>
-<li><a href="#kudu_impala_create_table">Creating a New Kudu Table From Impala</a></li>
-<li><a href="#_optimizing_performance_for_evaluating_sql_predicates">Optimizing Performance for Evaluating SQL Predicates</a></li>
-<li><a href="#partitioning_tables">Partitioning Tables</a></li>
-<li><a href="#_inserting_data_into_kudu_tables">Inserting Data Into Kudu Tables</a></li>
-<li><a href="#_updating_a_row">Updating a Row</a></li>
-<li><a href="#_deleting_a_row">Deleting a Row</a></li>
-<li><a href="#impala_insertion_caveat">Failures During <code>INSERT</code>, <code>UPDATE</code>, and <code>DELETE</code> Operations</a></li>
-<li><a href="#_altering_table_properties">Altering Table Properties</a></li>
-<li><a href="#_dropping_a_kudu_table_using_impala">Dropping a Kudu Table Using Impala</a></li>
-</ul>
-</li>
-<li><a href="#_what_s_next">What’s Next?</a>
-<ul class="sectlevel2">
-<li><a href="#_known_issues_and_limitations">Known Issues and Limitations</a></li>
-</ul>
-</li>
-</ul>
- </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>
\ No newline at end of file