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PostgreSQL documentation
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<refentry id="SQL-ALTERDATABASE">
 <refmeta>
  <refentrytitle id="sql-alterdatabase-title">ALTER DATABASE</refentrytitle>
  <refmiscinfo>SQL - Language Statements</refmiscinfo>
 </refmeta>

 <refnamediv>
  <refname>ALTER DATABASE</refname>
  <refpurpose>change a database</refpurpose>
 </refnamediv>

 <refsynopsisdiv>
<synopsis>
ALTER DATABASE <replaceable class="PARAMETER">name</replaceable> SET <replaceable>variable</replaceable> { TO | = } { <replaceable>value</replaceable> | DEFAULT }
ALTER DATABASE <replaceable class="PARAMETER">name</replaceable> RESET <replaceable>variable</replaceable>
</synopsis>
 </refsynopsisdiv>

 <refsect1>
  <title>Description</title>

  <para>
   <command>ALTER DATABASE</command> is used to change the session
   default of a run-time configuration variable for a
   <productname>PostgreSQL</productname> database. Whenever a new
   session is subsequently started in that database, the specified
   value becomes the session default value.
   The database-specific default
   overrides whatever setting is present in <filename>postgresql.conf</>
   or has been received from the <command>postmaster</command> command line.
  </para>

  <para>
   Only the database owner or a superuser can change the session defaults for a
   database.
  </para>
 </refsect1>

 <refsect1>
  <title>Parameters</title>

    <variablelist>
     <varlistentry>
      <term><replaceable class="PARAMETER">name</replaceable></term>
      <listitem>
       <para>
	The name of the database whose session defaults are to be altered.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry>
      <term><replaceable>variable</replaceable></term>
      <term><replaceable>value</replaceable></term>
      <listitem>
       <para>
        Set the session default for this database of the specified
        configuration variable to the given value.  If
        <replaceable>value</replaceable> is <literal>DEFAULT</literal>
        or, equivalently, <literal>RESET</literal> is used, the
        database-specific variable setting is removed and the system-wide
	default
        setting will be inherited in new sessions.  Use <literal>RESET
        ALL</literal> to clear all settings.
       </para>

       <para>
        See <xref linkend="sql-set" endterm="sql-set-title"> and <xref linkend="runtime-config">
        for more information about allowed variable names
        and values.
       </para>
      </listitem>
     </varlistentry>
    </variablelist>
 </refsect1>

 <refsect1>
  <title>Diagnostics</title>

   <variablelist>
    <varlistentry>
     <term><computeroutput>ALTER DATABASE</computeroutput></term>
     <listitem>
      <para>
       Message returned if the alteration was successful.
      </para>
     </listitem>
    </varlistentry>
     
    <varlistentry>
     <term><computeroutput>ERROR:  database "dbname" does not exist</computeroutput></term>
     <listitem>
      <para>
       Error message returned if the specified database is not known
       to the system.
      </para>
     </listitem>
    </varlistentry>
   </variablelist>
 </refsect1>

 <refsect1>
  <title>Notes</title>

  <para>
   Using <xref linkend="sql-alteruser" endterm="sql-alteruser-title">,
   it is also possible to tie a session default to a specific user
   rather than a database.  User-specific settings override database-specific
   ones if there is a conflict.
  </para>
 </refsect1>

 <refsect1>
  <title>Examples</title>

  <para>
   To disable index scans by default in the database
   <literal>test</literal>:

<programlisting>
ALTER DATABASE test SET enable_indexscan TO off;
</programlisting>
  </para>
 </refsect1>

 <refsect1>
  <title>Compatibility</title>
    
  <para>
   The <command>ALTER DATABASE</command> statement is a
   <productname>PostgreSQL</productname> extension.
  </para>
 </refsect1>

 <refsect1>
  <title>See Also</title>

  <simplelist type="inline">
   <member><xref linkend="sql-alteruser" endterm="sql-alteruser-title"></member>
   <member><xref linkend="sql-createdatabase" endterm="sql-createdatabase-title"></member>
   <member><xref linkend="sql-dropdatabase" endterm="sql-dropdatabase-title"></member>
   <member><xref linkend="sql-set" endterm="sql-set-title"></member>
  </simplelist>
 </refsect1>
</refentry>

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