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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 CLASS</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 V1.79.1" /><link rel="prev" href="sql-createoperator.html" title="CREATE OPERATOR" /><link rel="next" href="sql-createopfamily.html" title="CREATE OPERATOR FAMILY" /></head><body><div xmlns="http://www.w3.org/TR/xhtml1/transitional" class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="5" align="center">CREATE OPERATOR CLASS</th></tr><tr><td width="10%" align="left"><a accesskey="p" href="sql-createoperator.html" title="CREATE OPERATOR">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 12.4 Documentation">Home</a></td><td width="10%" align="right"> <a accesskey="n" href="sql-createopfamily.html" title="CREATE OPERATOR FAMILY">Next</a></td></tr></table><hr></hr></div><div class="refentry" id="SQL-CREATEOPCLASS"><div class="titlepage"></div><a id="id-1.9.3.73.1" class="indexterm"></a><div class="refnamediv"><h2><span class="refentrytitle">CREATE OPERATOR CLASS</span></h2><p>CREATE OPERATOR CLASS — define a new operator class</p></div><div class="refsynopsisdiv"><h2>Synopsis</h2><pre class="synopsis">
CREATE OPERATOR CLASS <em class="replaceable"><code>name</code></em> [ DEFAULT ] FOR TYPE <em class="replaceable"><code>data_type</code></em>
  USING <em class="replaceable"><code>index_method</code></em> [ FAMILY <em class="replaceable"><code>family_name</code></em> ] AS
  {  OPERATOR <em class="replaceable"><code>strategy_number</code></em> <em class="replaceable"><code>operator_name</code></em> [ ( <em class="replaceable"><code>op_type</code></em>, <em class="replaceable"><code>op_type</code></em> ) ] [ FOR SEARCH | FOR ORDER BY <em class="replaceable"><code>sort_family_name</code></em> ]
   | FUNCTION <em class="replaceable"><code>support_number</code></em> [ ( <em class="replaceable"><code>op_type</code></em> [ , <em class="replaceable"><code>op_type</code></em> ] ) ] <em class="replaceable"><code>function_name</code></em> ( <em class="replaceable"><code>argument_type</code></em> [, ...] )
   | STORAGE <em class="replaceable"><code>storage_type</code></em>
  } [, ... ]
</pre></div><div class="refsect1" id="id-1.9.3.73.5"><h2>Description</h2><p>
   <code class="command">CREATE OPERATOR CLASS</code> creates a new operator class.
   An operator class defines how a particular data type can be used with
   an index.  The operator class specifies that certain operators will fill
   particular roles or <span class="quote">“<span class="quote">strategies</span>”</span> for this data type and this
   index method.  The operator class also specifies the support functions to
   be used by
   the index method when the operator class is selected for an
   index column.  All the operators and functions used by an operator
   class must be defined before the operator class can be created.
  </p><p>
   If a schema name is given then the operator class is created in the
   specified schema.  Otherwise it is created in the current schema.
   Two operator classes in the same schema can have the same name only if they
   are for different index methods.
  </p><p>
   The user who defines an operator class becomes its owner.  Presently,
   the creating user must be a superuser.  (This restriction is made because
   an erroneous operator class definition could confuse or even crash the
   server.)
  </p><p>
   <code class="command">CREATE OPERATOR CLASS</code> does not presently check
   whether the operator class definition includes all the operators and
   functions required by the index method, nor whether the operators and
   functions form a self-consistent set.  It is the user's
   responsibility to define a valid operator class.
  </p><p>
   Related operator classes can be grouped into <em class="firstterm">operator
   families</em>.  To add a new operator class to an existing family,
   specify the <code class="literal">FAMILY</code> option in <code class="command">CREATE OPERATOR
   CLASS</code>.  Without this option, the new class is placed into
   a family named the same as the new class (creating that family if
   it doesn't already exist).
  </p><p>
   Refer to <a class="xref" href="xindex.html" title="37.16. Interfacing Extensions to Indexes">Section 37.16</a> for further information.
  </p></div><div class="refsect1" id="id-1.9.3.73.6"><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 class to be created.  The name can be
      schema-qualified.
     </p></dd><dt><span class="term"><code class="literal">DEFAULT</code></span></dt><dd><p>
      If present, the operator class will become the default
      operator class for its data type.  At most one operator class
      can be the default for a specific data type and index method.
     </p></dd><dt><span class="term"><em class="replaceable"><code>data_type</code></em></span></dt><dd><p>
      The column data type that this operator class is for.
     </p></dd><dt><span class="term"><em class="replaceable"><code>index_method</code></em></span></dt><dd><p>
      The name of the index method this operator class is for.
     </p></dd><dt><span class="term"><em class="replaceable"><code>family_name</code></em></span></dt><dd><p>
      The name of the existing operator family to add this operator class to.
      If not specified, a family named the same as the operator class is
      used (creating it, if it doesn't already exist).
     </p></dd><dt><span class="term"><em class="replaceable"><code>strategy_number</code></em></span></dt><dd><p>
      The index method's strategy number for an operator
      associated with the operator class.
     </p></dd><dt><span class="term"><em class="replaceable"><code>operator_name</code></em></span></dt><dd><p>
      The name (optionally schema-qualified) of an operator associated
      with the operator class.
     </p></dd><dt><span class="term"><em class="replaceable"><code>op_type</code></em></span></dt><dd><p>
      In an <code class="literal">OPERATOR</code> clause,
      the operand data type(s) of the operator, or <code class="literal">NONE</code> to
      signify a left-unary or right-unary operator.  The operand data
      types can be omitted in the normal case where they are the same
      as the operator class's data type.
     </p><p>
      In a <code class="literal">FUNCTION</code> clause, the operand data type(s) the
      function is intended to support, if different from
      the input data type(s) of the function (for B-tree comparison functions
      and hash functions)
      or the class's data type (for B-tree sort support functions and all
      functions in GiST, SP-GiST, GIN and BRIN operator classes).  These defaults
      are correct, and so <em class="replaceable"><code>op_type</code></em> need not be specified in
      <code class="literal">FUNCTION</code> clauses, except for the case of a B-tree sort
      support function that is meant to support cross-data-type comparisons.
     </p></dd><dt><span class="term"><em class="replaceable"><code>sort_family_name</code></em></span></dt><dd><p>
      The name (optionally schema-qualified) of an existing <code class="literal">btree</code> operator
      family that describes the sort ordering associated with an ordering
      operator.
     </p><p>
      If neither <code class="literal">FOR SEARCH</code> nor <code class="literal">FOR ORDER BY</code> is
      specified, <code class="literal">FOR SEARCH</code> is the default.
     </p></dd><dt><span class="term"><em class="replaceable"><code>support_number</code></em></span></dt><dd><p>
      The index method's support function number for a
      function associated with the operator class.
     </p></dd><dt><span class="term"><em class="replaceable"><code>function_name</code></em></span></dt><dd><p>
      The name (optionally schema-qualified) of a function that is an
      index method support function for the operator class.
     </p></dd><dt><span class="term"><em class="replaceable"><code>argument_type</code></em></span></dt><dd><p>
      The parameter data type(s) of the function.
     </p></dd><dt><span class="term"><em class="replaceable"><code>storage_type</code></em></span></dt><dd><p>
      The data type actually stored in the index.  Normally this is
      the same as the column data type, but some index methods
      (currently GiST, GIN and BRIN) allow it to be different.  The
      <code class="literal">STORAGE</code> clause must be omitted unless the index
      method allows a different type to be used.
      If the column <em class="replaceable"><code>data_type</code></em> is specified
      as <code class="type">anyarray</code>, the <em class="replaceable"><code>storage_type</code></em>
      can be declared as <code class="type">anyelement</code> to indicate that the index
      entries are members of the element type belonging to the actual array
      type that each particular index is created for.
     </p></dd></dl></div><p>
   The <code class="literal">OPERATOR</code>, <code class="literal">FUNCTION</code>, and <code class="literal">STORAGE</code>
   clauses can appear in any order.
  </p></div><div class="refsect1" id="id-1.9.3.73.7"><h2>Notes</h2><p>
   Because the index machinery does not check access permissions on functions
   before using them, including a function or operator in an operator class
   is tantamount to granting public execute permission on it.  This is usually
   not an issue for the sorts of functions that are useful in an operator
   class.
  </p><p>
   The operators should not be defined by SQL functions.  A SQL function
   is likely to be inlined into the calling query, which will prevent
   the optimizer from recognizing that the query matches an index.
  </p><p>
   Before <span class="productname">PostgreSQL</span> 8.4, the <code class="literal">OPERATOR</code>
   clause could include a <code class="literal">RECHECK</code> option.  This is no longer
   supported because whether an index operator is <span class="quote">“<span class="quote">lossy</span>”</span> is now
   determined on-the-fly at run time.  This allows efficient handling of
   cases where an operator might or might not be lossy.
  </p></div><div class="refsect1" id="id-1.9.3.73.8"><h2>Examples</h2><p>
   The following example command defines a GiST index operator class
   for the data type <code class="literal">_int4</code> (array of <code class="type">int4</code>).  See the
   <a class="xref" href="intarray.html" title="F.18. intarray">intarray</a> module for the complete example.
  </p><pre class="programlisting">
CREATE OPERATOR CLASS gist__int_ops
    DEFAULT FOR TYPE _int4 USING gist AS
        OPERATOR        3       &amp;&amp;,
        OPERATOR        6       = (anyarray, anyarray),
        OPERATOR        7       @&gt;,
        OPERATOR        8       &lt;@,
        OPERATOR        20      @@ (_int4, query_int),
        FUNCTION        1       g_int_consistent (internal, _int4, smallint, oid, internal),
        FUNCTION        2       g_int_union (internal, internal),
        FUNCTION        3       g_int_compress (internal),
        FUNCTION        4       g_int_decompress (internal),
        FUNCTION        5       g_int_penalty (internal, internal, internal),
        FUNCTION        6       g_int_picksplit (internal, internal),
        FUNCTION        7       g_int_same (_int4, _int4, internal);
</pre></div><div class="refsect1" id="id-1.9.3.73.9"><h2>Compatibility</h2><p>
   <code class="command">CREATE OPERATOR CLASS</code> is a
   <span class="productname">PostgreSQL</span> extension.  There is no
   <code class="command">CREATE OPERATOR CLASS</code> statement in the SQL
   standard.
  </p></div><div class="refsect1" id="id-1.9.3.73.10"><h2>See Also</h2><span class="simplelist"><a class="xref" href="sql-alteropclass.html" title="ALTER OPERATOR CLASS"><span class="refentrytitle">ALTER OPERATOR CLASS</span></a>, <a class="xref" href="sql-dropopclass.html" title="DROP OPERATOR CLASS"><span class="refentrytitle">DROP OPERATOR CLASS</span></a>, <a class="xref" href="sql-createopfamily.html" title="CREATE OPERATOR FAMILY"><span class="refentrytitle">CREATE OPERATOR FAMILY</span></a>, <a class="xref" href="sql-alteropfamily.html" title="ALTER OPERATOR FAMILY"><span class="refentrytitle">ALTER OPERATOR FAMILY</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-createoperator.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="sql-commands.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="sql-createopfamily.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">CREATE OPERATOR </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> CREATE OPERATOR FAMILY</td></tr></table></div></body></html>