CREATE OPERATOR 
CLASS(7)					   SQL Commands 					  CREATE OPERATOR CLASS(7)

NAME

       CREATE OPERATOR CLASS - define a new operator class

SYNOPSIS

       CREATE OPERATOR CLASS name [ DEFAULT ] FOR TYPE data_type
	 USING index_method [ FAMILY family_name ] AS
	 {  OPERATOR strategy_number operator_name [ ( op_type, op_type ) ]
	  | FUNCTION support_number [ ( op_type [ , op_type ] ) ] funcname ( argument_type [, ...] )
	  | STORAGE storage_type
	 } [, ... ]

DESCRIPTION

       CREATE  OPERATOR  CLASS	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 ``strategies'' 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 col-
       umn. All the operators and functions used by an operator class must be defined before the operator class can be created.

       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.

       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.)

       CREATE OPERATOR CLASS 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.

       Related operator classes can be grouped into operator families. To add a new operator class to  an  existing  family,  specify  the  FAMILY
       option  in CREATE OPERATOR CLASS. 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).

       Refer to in the documentation for further information.

PARAMETERS

       name   The name of the operator class to be created. The name can be schema-qualified.

       DEFAULT
	      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.

       data_type
	      The column data type that this operator class is for.

       index_method
	      The name of the index method this operator class is for.

       family_name
	      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).

       strategy_number
	      The index method's strategy number for an operator associated with the operator class.

       operator_name
	      The name (optionally schema-qualified) of an operator associated with the operator class.

       op_type
	      In an OPERATOR clause, the operand data type(s) of the operator, or NONE to signify a left-unary or right-unary operator. The  oper-
	      and data types can be omitted in the normal case where they are the same as the operator class's data type.

	      In  a FUNCTION 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 op_type in a FUNCTION clause in CREATE OPERATOR CLASS, but the option is provided for consistency
	      with the comparable syntax in ALTER OPERATOR FAMILY.

       support_number
	      The index method's support procedure number for a function associated with the operator class.

       funcname
	      The name (optionally schema-qualified) of a function that is an index method support procedure for the operator class.

       argument_types
	      The parameter data type(s) of the function.

       storage_type
	      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 STORAGE clause must be omitted unless the index method allows a different type to be used.

       The OPERATOR, FUNCTION, and STORAGE clauses can appear in any order.

NOTES

       Because the index machinery does not check access permissions on functions before using them, including a function or operator in an opera-
       tor class is tantamount to granting public execute permission on it. This is usually not an issue for the sorts of functions that are  use-
       ful in an operator class.

       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.

       Before PostgreSQL 8.4, the OPERATOR clause could include a RECHECK option. This is no longer supported because whether an index operator is
       ``lossy'' is now determined on-the-fly at runtime. This allows efficient handling of cases where an operator might or might not be lossy.

EXAMPLES

       The  following  example	command defines a GiST index operator class for the data type _int4 (array of int4). See contrib/intarray/ for the
       complete example.

       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);

COMPATIBILITY

       CREATE OPERATOR CLASS is a PostgreSQL extension. There is no CREATE OPERATOR CLASS statement in the SQL standard.

SEE ALSO

       ALTER OPERATOR CLASS [alter_operator_class(7)], DROP OPERATOR CLASS [drop_operator_class(7)], CREATE OPERATOR FAMILY  [create_operator_fam-
       ily(7)], ALTER OPERATOR FAMILY [alter_operator_family(7)]

SQL - Language Statements					    2010-05-14						  CREATE OPERATOR CLASS(7)