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><H1
><A
NAME="SQL-CREATEOPCLASS"
></A
>CREATE OPERATOR CLASS</H1
><DIV
CLASS="REFNAMEDIV"
><A
NAME="AEN57808"
></A
><H2
>Name</H2
>CREATE OPERATOR CLASS -- define a new operator class</DIV
><A
NAME="AEN57811"
></A
><DIV
CLASS="REFSYNOPSISDIV"
><A
NAME="AEN57813"
></A
><H2
>Synopsis</H2
><PRE
CLASS="SYNOPSIS"
>CREATE OPERATOR CLASS <TT
CLASS="REPLACEABLE"
><I
>name</I
></TT
> [ DEFAULT ] FOR TYPE <TT
CLASS="REPLACEABLE"
><I
>data_type</I
></TT
>
USING <TT
CLASS="REPLACEABLE"
><I
>index_method</I
></TT
> [ FAMILY <TT
CLASS="REPLACEABLE"
><I
>family_name</I
></TT
> ] AS
{ OPERATOR <TT
CLASS="REPLACEABLE"
><I
>strategy_number</I
></TT
> <TT
CLASS="REPLACEABLE"
><I
>operator_name</I
></TT
> [ ( <TT
CLASS="REPLACEABLE"
><I
>op_type</I
></TT
>, <TT
CLASS="REPLACEABLE"
><I
>op_type</I
></TT
> ) ]
| FUNCTION <TT
CLASS="REPLACEABLE"
><I
>support_number</I
></TT
> [ ( <TT
CLASS="REPLACEABLE"
><I
>op_type</I
></TT
> [ , <TT
CLASS="REPLACEABLE"
><I
>op_type</I
></TT
> ] ) ] <TT
CLASS="REPLACEABLE"
><I
>funcname</I
></TT
> ( <TT
CLASS="REPLACEABLE"
><I
>argument_type</I
></TT
> [, ...] )
| STORAGE <TT
CLASS="REPLACEABLE"
><I
>storage_type</I
></TT
>
} [, ... ]</PRE
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN57829"
></A
><H2
>Description</H2
><P
> <TT
CLASS="COMMAND"
>CREATE OPERATOR CLASS</TT
> 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"
>"strategies"</SPAN
> for this data type and this
index method. The operator class also specifies the support procedures 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
> <TT
CLASS="COMMAND"
>CREATE OPERATOR CLASS</TT
> 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 <I
CLASS="FIRSTTERM"
>operator
families</I
>. To add a new operator class to an existing family,
specify the <TT
CLASS="LITERAL"
>FAMILY</TT
> option in <TT
CLASS="COMMAND"
>CREATE OPERATOR
CLASS</TT
>. 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
HREF="xindex.html"
>Section 34.14</A
> for further information.
</P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN57844"
></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 class to be created. The name can be
schema-qualified.
</P
></DD
><DT
><TT
CLASS="LITERAL"
>DEFAULT</TT
></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
><TT
CLASS="REPLACEABLE"
><I
>data_type</I
></TT
></DT
><DD
><P
> The column data type that this operator class is for.
</P
></DD
><DT
><TT
CLASS="REPLACEABLE"
><I
>index_method</I
></TT
></DT
><DD
><P
> The name of the index method this operator class is for.
</P
></DD
><DT
><TT
CLASS="REPLACEABLE"
><I
>family_name</I
></TT
></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
><TT
CLASS="REPLACEABLE"
><I
>strategy_number</I
></TT
></DT
><DD
><P
> The index method's strategy number for an operator
associated with the operator class.
</P
></DD
><DT
><TT
CLASS="REPLACEABLE"
><I
>operator_name</I
></TT
></DT
><DD
><P
> The name (optionally schema-qualified) of an operator associated
with the operator class.
</P
></DD
><DT
><TT
CLASS="REPLACEABLE"
><I
>op_type</I
></TT
></DT
><DD
><P
> In an <TT
CLASS="LITERAL"
>OPERATOR</TT
> clause,
the operand data type(s) of the operator, or <TT
CLASS="LITERAL"
>NONE</TT
> 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 <TT
CLASS="LITERAL"
>FUNCTION</TT
> 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 and hash indexes)
or the class's data type (for GIN and GiST indexes). These defaults
are always correct, so there is no point in specifying <TT
CLASS="REPLACEABLE"
><I
>op_type</I
></TT
> in a <TT
CLASS="LITERAL"
>FUNCTION</TT
> clause
in <TT
CLASS="COMMAND"
>CREATE OPERATOR CLASS</TT
>, but the option is provided
for consistency with the comparable syntax in
<TT
CLASS="COMMAND"
>ALTER OPERATOR FAMILY</TT
>.
</P
></DD
><DT
><TT
CLASS="REPLACEABLE"
><I
>support_number</I
></TT
></DT
><DD
><P
> The index method's support procedure number for a
function associated with the operator class.
</P
></DD
><DT
><TT
CLASS="REPLACEABLE"
><I
>funcname</I
></TT
></DT
><DD
><P
> The name (optionally schema-qualified) of a function that is an
index method support procedure for the operator class.
</P
></DD
><DT
><TT
CLASS="REPLACEABLE"
><I
>argument_types</I
></TT
></DT
><DD
><P
> The parameter data type(s) of the function.
</P
></DD
><DT
><TT
CLASS="REPLACEABLE"
><I
>storage_type</I
></TT
></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 GIN and GiST) allow it to be different. The
<TT
CLASS="LITERAL"
>STORAGE</TT
> clause must be omitted unless the index
method allows a different type to be used.
</P
></DD
></DL
></DIV
><P
> The <TT
CLASS="LITERAL"
>OPERATOR</TT
>, <TT
CLASS="LITERAL"
>FUNCTION</TT
>, and <TT
CLASS="LITERAL"
>STORAGE</TT
>
clauses can appear in any order.
</P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN57920"
></A
><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 <TT
CLASS="LITERAL"
>OPERATOR</TT
>
clause could include a <TT
CLASS="LITERAL"
>RECHECK</TT
> option. This is no longer
supported because whether an index operator is <SPAN
CLASS="QUOTE"
>"lossy"</SPAN
> is now
determined on-the-fly at runtime. This allows efficient handling of
cases where an operator might or might not be lossy.
</P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN57929"
></A
><H2
>Examples</H2
><P
> The following example command defines a GiST index operator class
for the data type <TT
CLASS="LITERAL"
>_int4</TT
> (array of <TT
CLASS="TYPE"
>int4</TT
>). See
<TT
CLASS="FILENAME"
>contrib/intarray/</TT
> for the complete example.
</P
><PRE
CLASS="PROGRAMLISTING"
>CREATE OPERATOR CLASS gist__int_ops
DEFAULT FOR TYPE _int4 USING gist AS
OPERATOR 3 &&,
OPERATOR 6 = (anyarray, anyarray),
OPERATOR 7 @>,
OPERATOR 8 <@,
OPERATOR 20 @@ (_int4, query_int),
FUNCTION 1 g_int_consistent (internal, _int4, int, 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"
><A
NAME="AEN57936"
></A
><H2
>Compatibility</H2
><P
> <TT
CLASS="COMMAND"
>CREATE OPERATOR CLASS</TT
> is a
<SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
> extension. There is no
<TT
CLASS="COMMAND"
>CREATE OPERATOR CLASS</TT
> statement in the SQL
standard.
</P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN57942"
></A
><H2
>See Also</H2
><A
HREF="sql-alteropclass.html"
><I
>ALTER OPERATOR CLASS</I
></A
>, <A
HREF="sql-dropopclass.html"
><I
>DROP OPERATOR CLASS</I
></A
>, <A
HREF="sql-createopfamily.html"
><I
>CREATE OPERATOR FAMILY</I
></A
>, <A
HREF="sql-alteropfamily.html"
><I
>ALTER OPERATOR FAMILY</I
></A
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