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<title>CREATE OPERATOR</title>
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<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="refentry" lang="en">
<a name="sql-createoperator"></a><div class="titlepage"></div>
<div class="refnamediv">
<h2>Name</h2>
<p>CREATE OPERATOR — define a new operator</p>
</div>
<a name="id757804"></a><div class="refsynopsisdiv">
<h2>Synopsis</h2>
<pre class="synopsis">CREATE OPERATOR <em class="replaceable"><code>name</code></em> (
PROCEDURE = <em class="replaceable"><code>funcname</code></em>
[, LEFTARG = <em class="replaceable"><code>lefttype</code></em> ] [, RIGHTARG = <em class="replaceable"><code>righttype</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 ]
[, SORT1 = <em class="replaceable"><code>left_sort_op</code></em> ] [, SORT2 = <em class="replaceable"><code>right_sort_op</code></em> ]
[, LTCMP = <em class="replaceable"><code>less_than_op</code></em> ] [, GTCMP = <em class="replaceable"><code>greater_than_op</code></em> ]
)</pre>
</div>
<div class="refsect1" lang="en">
<a name="id757903"></a><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>+-*/<>=~!@#%^&|`?</p></div>
<p>
There are a few restrictions on your choice of name:
</p>
<div class="itemizedlist"><ul type="disc">
<li><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>
<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>~!@#%^&|`?</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>
</ul></div>
<p>
</p>
<p> The operator <code class="literal">!=</code> is mapped to
<code class="literal"><></code> on input, so these two names are always
equivalent.
</p>
<p> At least one of <code class="literal">LEFTARG</code> and <code class="literal">RIGHTARG</code> must be defined. For
binary operators, both must be defined. For right unary
operators, only <code class="literal">LEFTARG</code> should be defined, while for left
unary operators only <code class="literal">RIGHTARG</code> should be defined.
</p>
<p> The <em class="replaceable"><code>funcname</code></em>
procedure 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> The other clauses specify optional operator optimization clauses.
Their meaning is detailed in <a href="xoper-optimization.html" title="32.13.Operator Optimization Information">Section32.13, “Operator Optimization Information”</a>.
</p>
</div>
<div class="refsect1" lang="en">
<a name="id758097"></a><h2>Parameters</h2>
<div class="variablelist"><dl>
<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 may 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>funcname</code></em></span></dt>
<dd><p> The function used to implement this operator.
</p></dd>
<dt><span class="term"><em class="replaceable"><code>lefttype</code></em></span></dt>
<dd><p> The data type of the operator's left operand, if any.
This option would be omitted for a left-unary operator.
</p></dd>
<dt><span class="term"><em class="replaceable"><code>righttype</code></em></span></dt>
<dd><p> The data type of the operator's right operand, if any.
This option would be omitted for a right-unary operator.
</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>
<dt><span class="term"><em class="replaceable"><code>left_sort_op</code></em></span></dt>
<dd><p> If this operator can support a merge join, the less-than
operator that sorts the left-hand data type of this operator.
</p></dd>
<dt><span class="term"><em class="replaceable"><code>right_sort_op</code></em></span></dt>
<dd><p> If this operator can support a merge join, the less-than
operator that sorts the right-hand data type of this operator.
</p></dd>
<dt><span class="term"><em class="replaceable"><code>less_than_op</code></em></span></dt>
<dd><p> If this operator can support a merge join, the less-than
operator that compares the input data types of this operator.
</p></dd>
<dt><span class="term"><em class="replaceable"><code>greater_than_op</code></em></span></dt>
<dd><p> If this operator can support a merge join, the greater-than
operator that compares the input data types of this operator.
</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>
<p>
</p>
</div>
<div class="refsect1" lang="en">
<a name="id758326"></a><h2>Notes</h2>
<p> Refer to <a href="xoper.html" title="32.12.User-Defined Operators">Section32.12, “User-Defined Operators”</a> for further information.
</p>
<p> Use <a href="sql-dropoperator.html">DROP OPERATOR</a> to delete user-defined operators
from a database. Use <a href="sql-alteroperator.html">ALTER OPERATOR</a> to modify operators in a
database.
</p>
</div>
<div class="refsect1" lang="en">
<a name="id758367"></a><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,
PROCEDURE = area_equal_procedure,
COMMUTATOR = ===,
NEGATOR = !==,
RESTRICT = area_restriction_procedure,
JOIN = area_join_procedure,
HASHES,
SORT1 = <<<,
SORT2 = <<<
-- Since sort operators were given, MERGES is implied.
-- LTCMP and GTCMP are assumed to be < and > respectively
);</pre>
<p>
</p>
</div>
<div class="refsect1" lang="en">
<a name="id758393"></a><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" lang="en">
<a name="id758414"></a><h2>See Also</h2>
<span class="simplelist"><a href="sql-alteroperator.html">ALTER OPERATOR</a>, <a href="sql-createopclass.html">CREATE OPERATOR CLASS</a>, <a href="sql-dropoperator.html">DROP OPERATOR</a></span>
</div>
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