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   3 PostgreSQL documentation
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   5
   6 <refentry id="SQL-ALTERDATABASE">
   7  <refmeta>
   8   <refentrytitle id="sql-alterdatabase-title">ALTER DATABASE</refentrytitle>
   9   <refmiscinfo>SQL - Language Statements</refmiscinfo>
  10  </refmeta>
  11
  12  <refnamediv>
  13   <refname>ALTER DATABASE</refname>
  14   <refpurpose>change a database</refpurpose>
  15  </refnamediv>
  16
  17  <refsynopsisdiv>
  18 <synopsis>
  19 ALTER DATABASE <replaceable class="PARAMETER">name</replaceable> SET <replaceable>variable</replaceable> { TO | = } { <replaceable>value</replaceable> | DEFAULT }
  20 ALTER DATABASE <replaceable class="PARAMETER">name</replaceable> RESET <replaceable>variable</replaceable>
  21 </synopsis>
  22  </refsynopsisdiv>
  23
  24  <refsect1>
  25   <title>Description</title>
  26
  27   <para>
  28    <command>ALTER DATABASE</command> is used to change the session
  29    default of a run-time configuration variable for a
  30    <productname>PostgreSQL</productname> database. Whenever a new
  31    session is subsequently started in that database, <literal>SET
  32    <replaceable>variable</replaceable> TO
  33    <replaceable>value</replaceable></literal> is effectively executed
  34    before the start of the session.  The database-specific default
  35    overrides whatever setting is present in <filename>postgresql.conf</>
  36    or has been received from the postmaster.
  37   </para>
  38
  39   <para>
  40    Only a superuser or the database owner can change the session defaults for a
  41    database.
  42   </para>
  43
  44   <refsect2>
  45    <title>Parameters</title>
  46
  47    <para>
  48     <variablelist>
  49      <varlistentry>
  50       <term><replaceable class="PARAMETER">name</replaceable></term>
  51       <listitem>
  52        <para>
  53         The name of the database whose session defaults are to be altered.
  54        </para>
  55       </listitem>
  56      </varlistentry>
  57
  58      <varlistentry>
  59       <term><replaceable>variable</replaceable></term>
  60       <term><replaceable>value</replaceable></term>
  61       <listitem>
  62        <para>
  63         Set the session default for this database of the specified
  64         configuration variable to the given value.  If
  65         <replaceable>value</replaceable> is <literal>DEFAULT</literal>
  66         or, equivalently, <literal>RESET</literal> is used, the
  67         database-specific variable setting is removed and the default
  68         setting will be inherited in new sessions.  Use <literal>RESET
  69         ALL</literal> to clear all settings.
  70        </para>
  71
  72        <para>
  73         See <xref linkend="sql-set" endterm="sql-set-title"> and the
  74         <citetitle>Administrator's Guide</citetitle> for more
  75         information about allowed variable names and values.
  76        </para>
  77       </listitem>
  78      </varlistentry>
  79     </variablelist>
  80    </para>
  81   </refsect2>
  82  </refsect1>
  83
  84  <refsect1>
  85   <title>Diagnostics</title>
  86
  87   <para>
  88    <variablelist>
  89     <varlistentry>
  90      <term><computeroutput>ALTER DATABASE</computeroutput></term>
  91      <listitem>
  92       <para>
  93        Message returned if the alteration was successful.
  94       </para>
  95      </listitem>
  96     </varlistentry>
  97
  98     <varlistentry>
  99      <term><computeroutput>ERROR:  database "dbname" does not exist</computeroutput></term>
 100      <listitem>
 101       <para>
 102        Error message returned if the specified database is not known
 103        to the system.
 104       </para>
 105      </listitem>
 106     </varlistentry>
 107    </variablelist>
 108   </para>
 109  </refsect1>
 110
 111  <refsect1>
 112   <title>Notes</title>
 113
 114   <para>
 115    Using <xref linkend="sql-alteruser" endterm="sql-alteruser-title">,
 116    it is also possible to tie a session default to a specific user
 117    rather than a database.  User-specific settings override database-specific
 118    ones if there is a conflict.
 119   </para>
 120  </refsect1>
 121
 122  <refsect1>
 123   <title>Examples</title>
 124
 125   <para>
 126    To disable index scans by default in the database
 127    <literal>test</literal>:
 128
 129 <programlisting>
 130 ALTER DATABASE test SET enable_indexscan TO off;
 131 </programlisting>
 132   </para>
 133  </refsect1>
 134
 135  <refsect1>
 136   <title>Compatibility</title>
 137
 138   <para>
 139    The <command>ALTER DATABASE</command> statement is a
 140    <productname>PostgreSQL</productname> extension.
 141   </para>
 142  </refsect1>
 143
 144  <refsect1>
 145   <title>See Also</title>
 146
 147   <simplelist type="inline">
 148    <member><xref linkend="sql-alteruser" endterm="sql-alteruser-title"></member>
 149    <member><xref linkend="sql-createdatabase" endterm="sql-createdatabase-title"></member>
 150    <member><xref linkend="sql-dropdatabase" endterm="sql-dropdatabase-title"></member>
 151    <member><xref linkend="sql-set" endterm="sql-set-title"></member>
 152   </simplelist>
 153  </refsect1>
 154 </refentry>
 155
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