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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>CREATE OPERATOR</title><link rel="stylesheet" type="text/css" href="stylesheet.css" /><link rev="made" href="pgsql-docs@lists.postgresql.org" /><meta name="generator" content="DocBook XSL Stylesheets Vsnapshot" /><link rel="prev" href="sql-creatematerializedview.html" title="CREATE MATERIALIZED VIEW" /><link rel="next" href="sql-createopclass.html" title="CREATE OPERATOR CLASS" /></head><body id="docContent" class="container-fluid col-10"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="5" align="center">CREATE OPERATOR</th></tr><tr><td width="10%" align="left"><a accesskey="p" href="sql-creatematerializedview.html" title="CREATE MATERIALIZED VIEW">Prev</a> </td><td width="10%" align="left"><a accesskey="u" href="sql-commands.html" title="SQL Commands">Up</a></td><th width="60%" align="center">SQL Commands</th><td width="10%" align="right"><a accesskey="h" href="index.html" title="PostgreSQL 18.4 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="sql-createopclass.html" title="CREATE OPERATOR CLASS">Next</a></td></tr></table><hr /></div><div class="refentry" id="SQL-CREATEOPERATOR"><div class="titlepage"></div><a id="id-1.9.3.72.1" class="indexterm"></a><div class="refnamediv"><h2><span class="refentrytitle">CREATE OPERATOR</span></h2><p>CREATE OPERATOR — define a new operator</p></div><div class="refsynopsisdiv"><h2>Synopsis</h2><pre class="synopsis">
CREATE OPERATOR <em class="replaceable"><code>name</code></em> (
    {FUNCTION|PROCEDURE} = <em class="replaceable"><code>function_name</code></em>
    [, LEFTARG = <em class="replaceable"><code>left_type</code></em> ] [, RIGHTARG = <em class="replaceable"><code>right_type</code></em> ]
    [, COMMUTATOR = <em class="replaceable"><code>com_op</code></em> ] [, NEGATOR = <em class="replaceable"><code>neg_op</code></em> ]
    [, RESTRICT = <em class="replaceable"><code>res_proc</code></em> ] [, JOIN = <em class="replaceable"><code>join_proc</code></em> ]
    [, HASHES ] [, MERGES ]
)
</pre></div><div class="refsect1" id="id-1.9.3.72.5"><h2>Description</h2><p>
   <code class="command">CREATE OPERATOR</code> defines a new operator,
   <em class="replaceable"><code>name</code></em>.  The user who
   defines an operator becomes its owner.  If a schema name is given
   then the operator is created in the specified schema.  Otherwise it
   is created in the current schema.
  </p><p>
   The operator name is a sequence of up to <code class="symbol">NAMEDATALEN</code>-1
   (63 by default) characters from the following list:
</p><div class="literallayout"><p><br />
+ - * / &lt; &gt; = ~ ! @ # % ^ &amp; | ` ?<br />
</p></div><p>

   There are a few restrictions on your choice of name:
   </p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><p>
     <code class="literal">--</code> and <code class="literal">/*</code> cannot appear anywhere in an operator name,
     since they will be taken as the start of a comment.
     </p></li><li class="listitem"><p>
     A multicharacter operator name cannot end in <code class="literal">+</code> or
     <code class="literal">-</code>,
     unless the name also contains at least one of these characters:
</p><div class="literallayout"><p><br />
~ ! @ # % ^ &amp; | ` ?<br />
</p></div><p>
     For example, <code class="literal">@-</code> is an allowed operator name,
     but <code class="literal">*-</code> is not.
     This restriction allows <span class="productname">PostgreSQL</span> to
     parse SQL-compliant commands without requiring spaces between tokens.
     </p></li><li class="listitem"><p>
     The symbol <code class="literal">=&gt;</code> is reserved by the SQL grammar,
     so it cannot be used as an operator name.
     </p></li></ul></div><p>
  </p><p>
   The operator <code class="literal">!=</code> is mapped to
   <code class="literal">&lt;&gt;</code> on input, so these two names are always
   equivalent.
  </p><p>
   For binary operators, both <code class="literal">LEFTARG</code> and
   <code class="literal">RIGHTARG</code> must be defined.  For prefix operators only
   <code class="literal">RIGHTARG</code> should be defined.
   The <em class="replaceable"><code>function_name</code></em>
   function must have been previously defined using <code class="command">CREATE
   FUNCTION</code> and must be defined to accept the correct number
   of arguments (either one or two) of the indicated types.
  </p><p>
   In the syntax of <code class="literal">CREATE OPERATOR</code>, the keywords
   <code class="literal">FUNCTION</code> and <code class="literal">PROCEDURE</code> are
   equivalent, but the referenced function must in any case be a function, not
   a procedure.  The use of the keyword <code class="literal">PROCEDURE</code> here is
   historical and deprecated.
  </p><p>
   The other clauses specify optional operator optimization attributes.
   Their meaning is detailed in <a class="xref" href="xoper-optimization.html" title="36.15. Operator Optimization Information">Section 36.15</a>.
  </p><p>
   To be able to create an operator, you must have <code class="literal">USAGE</code>
   privilege on the argument types and the return type, as well
   as <code class="literal">EXECUTE</code> privilege on the underlying function.  If a
   commutator or negator operator is specified, you must own those operators.
  </p></div><div class="refsect1" id="id-1.9.3.72.6"><h2>Parameters</h2><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="replaceable"><code>name</code></em></span></dt><dd><p>
        The name of the operator to be defined. See above for allowable
        characters.  The name can be schema-qualified, for example
        <code class="literal">CREATE OPERATOR myschema.+ (...)</code>.  If not, then
        the operator is created in the current schema.  Two operators
        in the same schema can have the same name if they operate on
        different data types.  This is called
        <em class="firstterm">overloading</em>.
       </p></dd><dt><span class="term"><em class="replaceable"><code>function_name</code></em></span></dt><dd><p>
        The function used to implement this operator.
       </p></dd><dt><span class="term"><em class="replaceable"><code>left_type</code></em></span></dt><dd><p>
        The data type of the operator's left operand, if any.
        This option would be omitted for a prefix operator.
       </p></dd><dt><span class="term"><em class="replaceable"><code>right_type</code></em></span></dt><dd><p>
        The data type of the operator's right operand.
       </p></dd><dt><span class="term"><em class="replaceable"><code>com_op</code></em></span></dt><dd><p>
        The commutator of this operator.
       </p></dd><dt><span class="term"><em class="replaceable"><code>neg_op</code></em></span></dt><dd><p>
        The negator of this operator.
       </p></dd><dt><span class="term"><em class="replaceable"><code>res_proc</code></em></span></dt><dd><p>
        The restriction selectivity estimator function for this operator.
       </p></dd><dt><span class="term"><em class="replaceable"><code>join_proc</code></em></span></dt><dd><p>
        The join selectivity estimator function for this operator.
       </p></dd><dt><span class="term"><code class="literal">HASHES</code></span></dt><dd><p>
       Indicates this operator can support a hash join.
       </p></dd><dt><span class="term"><code class="literal">MERGES</code></span></dt><dd><p>
       Indicates this operator can support a merge join.
       </p></dd></dl></div><p>
   To give a schema-qualified operator name in <em class="replaceable"><code>com_op</code></em> or the other optional
   arguments, use the <code class="literal">OPERATOR()</code> syntax, for example:
</p><pre class="programlisting">
COMMUTATOR = OPERATOR(myschema.===) ,
</pre></div><div class="refsect1" id="id-1.9.3.72.7"><h2>Notes</h2><p>
   Refer to <a class="xref" href="xoper.html" title="36.14. User-Defined Operators">Section 36.14</a> and <a class="xref" href="xoper-optimization.html" title="36.15. Operator Optimization Information">Section 36.15</a>
   for further information.
  </p><p>
   When you are defining a self-commutative operator, you just do it.
   When you are defining a pair of commutative operators, things are
   a little trickier: how can the first one to be defined refer to the
   other one, which you haven't defined yet?  There are three solutions
   to this problem:

   </p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><p>
      One way is to omit the <code class="literal">COMMUTATOR</code> clause in the
      first operator that you define, and then provide one in the second
      operator's definition.  Since <span class="productname">PostgreSQL</span>
      knows that commutative operators come in pairs, when it sees the
      second definition it will automatically go back and fill in the
      missing <code class="literal">COMMUTATOR</code> clause in the first
      definition.
     </p></li><li class="listitem"><p>
      Another, more straightforward way is just to
      include <code class="literal">COMMUTATOR</code> clauses in both definitions.
      When <span class="productname">PostgreSQL</span> processes the first
      definition and realizes that <code class="literal">COMMUTATOR</code> refers to
      a nonexistent operator, the system will make a dummy entry for that
      operator in the system catalog.  This dummy entry will have valid
      data only for the operator name, left and right operand types, and
      owner, since that's all that <span class="productname">PostgreSQL</span>
      can deduce at this point.  The first operator's catalog entry will
      link to this dummy entry.  Later, when you define the second
      operator, the system updates the dummy entry with the additional
      information from the second definition.  If you try to use the dummy
      operator before it's been filled in, you'll just get an error
      message.
     </p></li><li class="listitem"><p>
      Alternatively, both operators can be defined
      without <code class="literal">COMMUTATOR</code> clauses
      and then <code class="command">ALTER OPERATOR</code> can be used to set their
      commutator links.  It's sufficient to <code class="command">ALTER</code>
      either one of the pair.
     </p></li></ul></div><p>

   In all three cases, you must own both operators in order to mark
   them as commutators.
  </p><p>
   Pairs of negator operators can be defined using the same methods
   as for commutator pairs.
  </p><p>
   It is not possible to specify an operator's lexical precedence in
   <code class="command">CREATE OPERATOR</code>, because the parser's precedence behavior
   is hard-wired.  See <a class="xref" href="sql-syntax-lexical.html#SQL-PRECEDENCE" title="4.1.6. Operator Precedence">Section 4.1.6</a> for precedence details.
  </p><p>
   The obsolete options <code class="literal">SORT1</code>, <code class="literal">SORT2</code>,
   <code class="literal">LTCMP</code>, and <code class="literal">GTCMP</code> were formerly used to
   specify the names of sort operators associated with a merge-joinable
   operator.  This is no longer necessary, since information about
   associated operators is found by looking at B-tree operator families
   instead.  If one of these options is given, it is ignored except
   for implicitly setting <code class="literal">MERGES</code> true.
  </p><p>
   Use <a class="link" href="sql-dropoperator.html" title="DROP OPERATOR"><code class="command">DROP OPERATOR</code></a> to delete user-defined operators
   from a database.  Use <a class="link" href="sql-alteroperator.html" title="ALTER OPERATOR"><code class="command">ALTER OPERATOR</code></a> to modify operators in a
   database.
  </p></div><div class="refsect1" id="id-1.9.3.72.8"><h2>Examples</h2><p>
   The following command defines a new operator, area-equality, for
   the data type <code class="type">box</code>:
</p><pre class="programlisting">
CREATE OPERATOR === (
    LEFTARG = box,
    RIGHTARG = box,
    FUNCTION = area_equal_function,
    COMMUTATOR = ===,
    NEGATOR = !==,
    RESTRICT = area_restriction_function,
    JOIN = area_join_function,
    HASHES, MERGES
);
</pre></div><div class="refsect1" id="id-1.9.3.72.9"><h2>Compatibility</h2><p>
   <code class="command">CREATE OPERATOR</code> is a
   <span class="productname">PostgreSQL</span> extension.  There are no
   provisions for user-defined operators in the SQL standard.
  </p></div><div class="refsect1" id="id-1.9.3.72.10"><h2>See Also</h2><span class="simplelist"><a class="xref" href="sql-alteroperator.html" title="ALTER OPERATOR"><span class="refentrytitle">ALTER OPERATOR</span></a>, <a class="xref" href="sql-createopclass.html" title="CREATE OPERATOR CLASS"><span class="refentrytitle">CREATE OPERATOR CLASS</span></a>, <a class="xref" href="sql-dropoperator.html" title="DROP OPERATOR"><span class="refentrytitle">DROP OPERATOR</span></a></span></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="sql-creatematerializedview.html" title="CREATE MATERIALIZED VIEW">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="sql-commands.html" title="SQL Commands">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="sql-createopclass.html" title="CREATE OPERATOR CLASS">Next</a></td></tr><tr><td width="40%" align="left" valign="top">CREATE MATERIALIZED VIEW </td><td width="20%" align="center"><a accesskey="h" href="index.html" title="PostgreSQL 18.4 Documentation">Home</a></td><td width="40%" align="right" valign="top"> CREATE OPERATOR CLASS</td></tr></table></div></body></html>