impala/docs/topics/impala_alter_view.xml

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<!DOCTYPE concept PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd">
<concept rev="1.1" id="alter_view">

  <title>ALTER VIEW Statement</title>

  <titlealts audience="PDF">

    <navtitle>ALTER VIEW</navtitle>

  </titlealts>

  <prolog>
    <metadata>
      <data name="Category" value="Impala"/>
      <data name="Category" value="SQL"/>
      <data name="Category" value="DDL"/>
      <data name="Category" value="Tables"/>
      <data name="Category" value="Schemas"/>
      <data name="Category" value="Views"/>
      <data name="Category" value="Developers"/>
      <data name="Category" value="Data Analysts"/>
    </metadata>
  </prolog>

  <conbody>

    <p>
      The <codeph>ALTER VIEW</codeph> statement changes the characteristics of a view.
    </p>

    <p>
      Because a view is a logical construct, an alias for a query, with no physical data behind
      it, <codeph>ALTER VIEW</codeph> only involves changes to metadata in the metastore
      database, not any data files in HDFS.
    </p>

    <p>
      To see the definition of the updated view, issue a <codeph>DESCRIBE FORMATTED</codeph>
      statement.
    </p>

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

<codeblock>ALTER VIEW [<varname>database_name</varname>.]<varname>view_name</varname>
   [(<varname>column_name</varname> [COMMENT '<varname>column_comment</varname>'][, ...])]
   AS <varname>select_statement</varname>;

ALTER VIEW [<varname>database_name</varname>.]<varname>view_name</varname>
   RENAME TO [<varname>database_name</varname>.]<varname>view_name</varname>;

ALTER VIEW [<varname>database_name</varname>.]<varname>view_name</varname> SET OWNER USER user_name;

ALTER VIEW [<varname>database_name</varname>.]<varname>view_name</varname>
    SET TBLPROPERTIES ('<varname>name</varname>' = '<varname>value</varname>'[, '<varname>name</varname>' = '<varname>value</varname>' ...]);

ALTER VIEW [<varname>database_name</varname>.]<varname>view_name</varname>
    UNSET TBLPROPERTIES ('<varname>name</varname>'[, ...]);
</codeblock>

    <ul>
      <li>
        The <codeph>AS</codeph> clause associates the view with a different query.
        <p>
          An optional list of column names can be specified with or without the column-level
          comments.
        </p>

        <p>
          For example:
<codeblock>
ALTER VIEW v1 AS SELECT x, UPPER(s) s FROM t2;
ALTER VIEW v1 (c1, c2) AS SELECT x, UPPER(s) s FROM t2;
ALTER VIEW v7 (c1 COMMENT 'Comment for c1', c2) AS SELECT t1.c1, t1.c2 FROM t1;
</codeblock>
        </p>
      </li>

      <li>
        The <codeph>RENAME TO</codeph> clause changes the name of the view, moves the view to a
        different database, or both.
        <p>
          For example:
<codeblock>ALTER VIEW db1.v1 RENAME TO db2.v2; -- Move the view to a different database with a new name.
ALTER VIEW db1.v1 RENAME TO db1.v2;  -- Rename the view in the same database.
ALTER VIEW db1.v1 RENAME TO db2.v1; -- Move the view to a difference database with the same view name.</codeblock>
        </p>
      </li>

      <li rev="3.1 IMPALA-6988">
        The <codeph>SET OWNER</codeph> clause transfers the ownership of the view from the
        current owner to another user.
        <p>
          The view owner is originally set to the user who creates the view.
          The term <codeph>OWNER</codeph> is used to differentiate between the
          <codeph>ALL</codeph> privilege that is explicitly granted via the
          <codeph>GRANT</codeph> statement and a privilege that is implicitly granted by the
          <codeph>CREATE VIEW</codeph> statement.
        </p>
      </li>

      <li rev="IMPALA-11420">
        The <codeph>SET TBLPROPERTIES</codeph> clause is primarily a way to associate arbitrary
        user-specified data items with a particular view.
        <p>
          You can associate arbitrary items of metadata with a table by specifying the
          <codeph>TBLPROPERTIES</codeph> clause. This clause takes a comma-separated list of
          key-value pairs and stores those items in the metastore database. You can also unset the
          view properties later with an <codeph>UNSET TBLPROPERTIES</codeph> clause.
        </p>

        <p>
          For example:
<codeblock>ALTER VIEW v1 SET TBLPROPERTIES ('tblp1' = '1', 'tblp2' = '2');
ALTER VIEW v1 UNSET TBLPROPERTIES ('tblp1', 'tblp2');
</codeblock>
        </p>
      </li>
    </ul>

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

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

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

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

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

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

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

    <p>
      <xref href="impala_views.xml#views"/>, <xref href="impala_create_view.xml#create_view"/>,
      <xref href="impala_drop_view.xml#drop_view"/>
    </p>

  </conbody>

</concept>