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RedHat 9 (Linux i386) - man page for create_operator_class (redhat section 7)

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

NAME
       CREATE OPERATOR CLASS - define a new operator class for indexes

SYNOPSIS
       CREATE OPERATOR CLASS name [ DEFAULT ] FOR TYPE data_type USING access_method AS
	 {  OPERATOR strategy_number operator_id [ ( type, type ) ] [ RECHECK ]
	  | FUNCTION support_number func_name ( parameter_types )
	  | STORAGE storage_type
	 } [, ... ]

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

       DEFAULT
	      If present, the operator class will become the default index operator class for its
	      data type. At most one operator class can be the default for a specific  data  type
	      and access method.

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

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

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

       operator_id
	      The identifier (optionally schema-qualified) of an  operator  associated	with  the
	      operator class.

       type   The  input  data	type(s) of an operator, or NONE to signify a left-unary or right-
	      unary operator. The input data types may be omitted in the normal case  where  they
	      are the same as the operator class's data type.

       RECHECK
	      If  present,  the index is ``lossy'' for this operator, and so the tuples retrieved
	      using the index must be rechecked to verify that they actually satisfy the qualifi-
	      cation clause involving this operator.

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

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

       parameter_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 access methods (only GIST at this writing) allow it to be
	      different. The STORAGE clause must be omitted unless the index access method allows
	      a different type to be used.

   OUTPUTS
       CREATE OPERATOR CLASS
	      Message returned if the operator class is successfully created.

DESCRIPTION
       CREATE OPERATOR CLASS defines a new operator class, name.

       An operator class defines how a particular data type can be used with an index. The opera-
       tor  class  specifies  that certain operators will fill particular roles or ``strategies''
       for this data type and this access method. The operator class also specifies  the  support
       procedures  to  be used by the index access 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 is created.

       If a schema name is given then the operator class is created in the specified schema. Oth-
       erwise it is created in the current schema (the one at the front of the search  path;  see
       CURRENT_SCHEMA()).  Two operator classes in the same schema can have the same name only if
       they are for different index access 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 defini-
       tion could confuse or even crash the server.)

       CREATE OPERATOR CLASS does not presently check whether the class definition  includes  all
       the  operators and functions required by the index access method. It is the user's respon-
       sibility to define a valid operator class.

       Refer to the chapter on interfacing extensions to indexes in the  PostgreSQL  Programmer's
       Guide for further information.

   NOTES
       Refer  to  DROP	OPERATOR  CLASS  [drop_operator_class(7)] to delete user-defined operator
       classes from a database.

USAGE
       The following example command defines a GiST index operator  class  for	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       =       RECHECK,
	       OPERATOR        7       @,
	       OPERATOR        8       ~,
	       OPERATOR        20      @@ (_int4, query_int),
	       FUNCTION        1       g_int_consistent (internal, _int4, int4),
	       FUNCTION        2       g_int_union (bytea, 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);

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

COMPATIBILITY
   SQL92
       CREATE OPERATOR CLASS is a PostgreSQL extension.  There is no CREATE OPERATOR CLASS state-
       ment in SQL92.

SQL - Language Statements		    2002-11-22			 CREATE OPERATOR CLASS(7)


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