docs/topics/impala_upsert.xml

<?xml version="1.0" encoding="UTF-8"?>
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<!DOCTYPE concept PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd">
<concept id="upsert" rev="kudu IMPALA-3725">

  <title>UPSERT Statement (<keyword keyref="impala28"/> or higher only)</title>
  <titlealts audience="PDF"><navtitle>UPSERT</navtitle></titlealts>
  <prolog>
    <metadata>
      <data name="Category" value="Impala"/>
      <data name="Category" value="SQL"/>
      <data name="Category" value="Kudu"/>
      <data name="Category" value="ETL"/>
      <data name="Category" value="Ingest"/>
      <data name="Category" value="DML"/>
      <data name="Category" value="Developers"/>
      <data name="Category" value="Data Analysts"/>
    </metadata>
  </prolog>

  <conbody>

    <p>
      <indexterm audience="hidden">UPSERT statement</indexterm>
      Acts as a combination of the <codeph>INSERT</codeph>
      and <codeph>UPDATE</codeph> statements.
      For each row processed by the <codeph>UPSERT</codeph>
      statement:
      <ul>
        <li>
          <p>
            If another row already exists with the same set of primary key
            values, the other columns are updated to match the values
            from the row being <q>UPSERTed</q>.
          </p>
        </li>
        <li>
          <p>
            If there is not any row with the same set of primary key values,
            the row is created, the same as if the <codeph>INSERT</codeph>
            statement was used.
          </p>
        </li>
      </ul>
    </p>

    <p>
      This statement only works for Impala tables that use the Kudu storage engine.
    </p>

    <p conref="../shared/impala_common.xml#common/syntax_blurb"/>

<codeblock>
UPSERT <ph rev="2.12.0 IMPALA-4168">[<varname>hint_clause</varname>]</ph> INTO [TABLE] [<varname>db_name</varname>.]<varname>table_name</varname>
  [(<varname>column_list</varname>)]
{
    [<varname>hint_clause</varname>] <varname>select_statement</varname>
  | VALUES (<varname>value</varname> [, <varname>value</varname> ...]) [, (<varname>value</varname> [, <varname>value</varname> ...]) ...]
}

hint_clause ::= [SHUFFLE] | [NOSHUFFLE]
  (Note: the square brackets are part of the syntax.)
</codeblock>

    <p>
      The <varname>select_statement</varname> clause can use the full syntax, such as
      <codeph>WHERE</codeph> and join clauses, as <xref href="impala_select.xml#select"/>.
    </p>

    <p conref="../shared/impala_common.xml#common/dml_blurb_kudu"/>

    <p conref="../shared/impala_common.xml#common/usage_notes_blurb"/>

    <p>
      If you specify a column list, any omitted columns in the inserted or updated rows are
      set to their default value (if the column has one) or <codeph>NULL</codeph> (if the
      column does not have a default value). Therefore, if a column is not nullable and
      has no default value, it must be included in the column list for any <codeph>UPSERT</codeph>
      statement. Because all primary key columns meet these conditions, all the primary key
      columns must be specified in every <codeph>UPSERT</codeph> statement.
    </p>

    <p>
      Because Kudu tables can efficiently handle small incremental changes, the <codeph>VALUES</codeph>
      clause is more practical to use with Kudu tables than with HDFS-based tables.
    </p>

    <note conref="../shared/impala_common.xml#common/compute_stats_next"/>

    <p conref="../shared/impala_common.xml#common/example_blurb"/>

<codeblock>
UPSERT INTO kudu_table (pk, c1, c2, c3) VALUES (0, 'hello', 50, true), (1, 'world', -1, false);
UPSERT INTO production_table SELECT * FROM staging_table;
UPSERT INTO production_table SELECT * FROM staging_table WHERE c1 IS NOT NULL AND c2 > 0;
</codeblock>

    <p conref="../shared/impala_common.xml#common/related_info"/>

    <p>
      <xref href="impala_kudu.xml#impala_kudu"/>,
      <xref href="impala_insert.xml#insert"/>,
      <xref href="impala_update.xml#update"/>
    </p>

  </conbody>

</concept>