docs/topics/impala_langref.xml

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<!DOCTYPE concept PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd">
<concept id="langref">

  <title>Impala SQL Language Reference</title>
  <titlealts audience="PDF"><navtitle>SQL Reference</navtitle></titlealts>
  <prolog>
    <metadata>
      <data name="Category" value="Impala"/>
      <data name="Category" value="SQL"/>
      <data name="Category" value="Data Analysts"/>
      <data name="Category" value="Developers"/>
      <data name="Category" value="impala-shell"/>
    </metadata>
  </prolog>

  <conbody>

    <p>
      Impala uses SQL as its query language. To protect user investment in skills development and query
      design, Impala provides a high degree of compatibility with the Hive Query Language (HiveQL):
    </p>

    <ul>
      <li>
        Because Impala uses the same metadata store as Hive to record information about table structure and
        properties, Impala can access tables defined through the native Impala <codeph>CREATE TABLE</codeph>
        command, or tables created using the Hive data definition language (DDL).
      </li>

      <li>
        Impala supports data manipulation (DML) statements similar to the DML component of HiveQL.
      </li>

      <li>
        Impala provides many <xref href="impala_functions.xml#builtins">built-in functions</xref> with the same
        names and parameter types as their HiveQL equivalents.
      </li>
    </ul>

    <p>
      Impala supports most of the same <xref href="impala_langref_sql.xml#langref_sql">statements and
      clauses</xref> as HiveQL, including, but not limited to <codeph>JOIN</codeph>, <codeph>AGGREGATE</codeph>,
      <codeph>DISTINCT</codeph>, <codeph>UNION ALL</codeph>, <codeph>ORDER BY</codeph>, <codeph>LIMIT</codeph> and
      (uncorrelated) subquery in the <codeph>FROM</codeph> clause. Impala also supports <codeph>INSERT
      INTO</codeph> and <codeph>INSERT OVERWRITE</codeph>.
    </p>

    <p>
      Impala supports data types with the same names and semantics as the equivalent Hive data types:
      <codeph>STRING</codeph>, <codeph>TINYINT</codeph>, <codeph>SMALLINT</codeph>, <codeph>INT</codeph>,
      <codeph>BIGINT</codeph>, <codeph>FLOAT</codeph>, <codeph>DOUBLE</codeph>, <codeph>BOOLEAN</codeph>,
      <codeph>STRING</codeph>, <codeph>TIMESTAMP</codeph>.
    </p>

    <p>
      For full details about Impala SQL syntax and semantics, see
      <xref href="impala_langref_sql.xml#langref_sql"/>.
    </p>

    <p>
      Most HiveQL <codeph>SELECT</codeph> and <codeph>INSERT</codeph> statements run unmodified with Impala. For
      information about Hive syntax not available in Impala, see
      <xref href="impala_langref_unsupported.xml#langref_hiveql_delta"/>.
    </p>

    <p>
      For a list of the built-in functions available in Impala queries, see
      <xref href="impala_functions.xml#builtins"/>.
    </p>

    <p outputclass="toc"/>
  </conbody>
</concept>