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><H1
><A
NAME="SQL-CREATEOPERATOR"
></A
>CREATE OPERATOR</H1
><DIV
CLASS="REFNAMEDIV"
><A
NAME="AEN52881"
></A
><H2
>Name</H2
>CREATE OPERATOR -- define a new operator</DIV
><A
NAME="AEN52884"
></A
><DIV
CLASS="REFSYNOPSISDIV"
><A
NAME="AEN52886"
></A
><H2
>Synopsis</H2
><PRE
CLASS="SYNOPSIS"
>CREATE OPERATOR <TT
CLASS="REPLACEABLE"
><I
>name</I
></TT
> (
PROCEDURE = <TT
CLASS="REPLACEABLE"
><I
>funcname</I
></TT
>
[, LEFTARG = <TT
CLASS="REPLACEABLE"
><I
>lefttype</I
></TT
> ] [, RIGHTARG = <TT
CLASS="REPLACEABLE"
><I
>righttype</I
></TT
> ]
[, COMMUTATOR = <TT
CLASS="REPLACEABLE"
><I
>com_op</I
></TT
> ] [, NEGATOR = <TT
CLASS="REPLACEABLE"
><I
>neg_op</I
></TT
> ]
[, RESTRICT = <TT
CLASS="REPLACEABLE"
><I
>res_proc</I
></TT
> ] [, JOIN = <TT
CLASS="REPLACEABLE"
><I
>join_proc</I
></TT
> ]
[, HASHES ] [, MERGES ]
)</PRE
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN52896"
></A
><H2
>Description</H2
><P
> <TT
CLASS="COMMAND"
>CREATE OPERATOR</TT
> defines a new operator,
<TT
CLASS="REPLACEABLE"
><I
>name</I
></TT
>. 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 <TT
CLASS="SYMBOL"
>NAMEDATALEN</TT
>-1
(63 by default) characters from the following list:
<P
CLASS="LITERALLAYOUT"
>+ - * / < > = ~ ! @ # % ^ & | ` ?</P
>
There are a few restrictions on your choice of name:
<P
></P
></P><UL
><LI
><P
> <TT
CLASS="LITERAL"
>--</TT
> and <TT
CLASS="LITERAL"
>/*</TT
> 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 <TT
CLASS="LITERAL"
>+</TT
> or
<TT
CLASS="LITERAL"
>-</TT
>,
unless the name also contains at least one of these characters:
<P
CLASS="LITERALLAYOUT"
>~ ! @ # % ^ & | ` ?</P
>
For example, <TT
CLASS="LITERAL"
>@-</TT
> is an allowed operator name,
but <TT
CLASS="LITERAL"
>*-</TT
> is not.
This restriction allows <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
> to
parse SQL-compliant commands without requiring spaces between tokens.
</P
></LI
></UL
><P>
</P
><P
> The operator <TT
CLASS="LITERAL"
>!=</TT
> is mapped to
<TT
CLASS="LITERAL"
><></TT
> on input, so these two names are always
equivalent.
</P
><P
> At least one of <TT
CLASS="LITERAL"
>LEFTARG</TT
> and <TT
CLASS="LITERAL"
>RIGHTARG</TT
> must be defined. For
binary operators, both must be defined. For right unary
operators, only <TT
CLASS="LITERAL"
>LEFTARG</TT
> should be defined, while for left
unary operators only <TT
CLASS="LITERAL"
>RIGHTARG</TT
> should be defined.
</P
><P
> The <TT
CLASS="REPLACEABLE"
><I
>funcname</I
></TT
>
procedure must have been previously defined using <TT
CLASS="COMMAND"
>CREATE
FUNCTION</TT
> 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"
>Section 34.13</A
>.
</P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN52930"
></A
><H2
>Parameters</H2
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
><TT
CLASS="REPLACEABLE"
><I
>name</I
></TT
></DT
><DD
><P
> The name of the operator to be defined. See above for allowable
characters. The name can be schema-qualified, for example
<TT
CLASS="LITERAL"
>CREATE OPERATOR myschema.+ (...)</TT
>. 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
<I
CLASS="FIRSTTERM"
>overloading</I
>.
</P
></DD
><DT
><TT
CLASS="REPLACEABLE"
><I
>funcname</I
></TT
></DT
><DD
><P
> The function used to implement this operator.
</P
></DD
><DT
><TT
CLASS="REPLACEABLE"
><I
>lefttype</I
></TT
></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
><TT
CLASS="REPLACEABLE"
><I
>righttype</I
></TT
></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
><TT
CLASS="REPLACEABLE"
><I
>com_op</I
></TT
></DT
><DD
><P
> The commutator of this operator.
</P
></DD
><DT
><TT
CLASS="REPLACEABLE"
><I
>neg_op</I
></TT
></DT
><DD
><P
> The negator of this operator.
</P
></DD
><DT
><TT
CLASS="REPLACEABLE"
><I
>res_proc</I
></TT
></DT
><DD
><P
> The restriction selectivity estimator function for this operator.
</P
></DD
><DT
><TT
CLASS="REPLACEABLE"
><I
>join_proc</I
></TT
></DT
><DD
><P
> The join selectivity estimator function for this operator.
</P
></DD
><DT
><TT
CLASS="LITERAL"
>HASHES</TT
></DT
><DD
><P
> Indicates this operator can support a hash join.
</P
></DD
><DT
><TT
CLASS="LITERAL"
>MERGES</TT
></DT
><DD
><P
> Indicates this operator can support a merge join.
</P
></DD
></DL
></DIV
><P
> To give a schema-qualified operator name in <TT
CLASS="REPLACEABLE"
><I
>com_op</I
></TT
> or the other optional
arguments, use the <TT
CLASS="LITERAL"
>OPERATOR()</TT
> syntax, for example:
</P><PRE
CLASS="PROGRAMLISTING"
>COMMUTATOR = OPERATOR(myschema.===) ,</PRE
><P>
</P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN52989"
></A
><H2
>Notes</H2
><P
> Refer to <A
HREF="xoper.html"
>Section 34.12</A
> for further information.
</P
><P
> The obsolete options <TT
CLASS="LITERAL"
>SORT1</TT
>, <TT
CLASS="LITERAL"
>SORT2</TT
>,
<TT
CLASS="LITERAL"
>LTCMP</TT
>, and <TT
CLASS="LITERAL"
>GTCMP</TT
> 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 <TT
CLASS="LITERAL"
>MERGES</TT
> true.
</P
><P
> Use <A
HREF="sql-dropoperator.html"
><I
>DROP OPERATOR</I
></A
> to delete user-defined operators
from a database. Use <A
HREF="sql-alteroperator.html"
><I
>ALTER OPERATOR</I
></A
> to modify operators in a
database.
</P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN53002"
></A
><H2
>Examples</H2
><P
> The following command defines a new operator, area-equality, for
the data type <TT
CLASS="TYPE"
>box</TT
>:
</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, MERGES
);</PRE
><P>
</P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN53007"
></A
><H2
>Compatibility</H2
><P
> <TT
CLASS="COMMAND"
>CREATE OPERATOR</TT
> 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"
><A
NAME="AEN53012"
></A
><H2
>See Also</H2
><A
HREF="sql-alteroperator.html"
><I
>ALTER OPERATOR</I
></A
>, <A
HREF="sql-createopclass.html"
><I
>CREATE OPERATOR CLASS</I
></A
>, <A
HREF="sql-dropoperator.html"
><I
>DROP OPERATOR</I
></A
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