create_operator_class man page on Scientific

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       CREATE OPERATOR CLASS - define a new operator class

	 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
	 } [, ... ]

       CREATE  OPERATOR CLASS creates a new operator class.  An operator class
       defines how a particular data type can be used with an index. The oper‐
       ator  class specifies that certain operators will fill particular roles
       or ``strategies'' for this data type and this index method. The	opera‐
       tor 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.

       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 oper‐
       ator 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.

       name   The name of the operator class to be created. The	 name  can  be

	      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.

	      The column data type that this operator class is for.

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

	      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

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

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

	      In an OPERATOR clause, the operand data type(s) of the operator,
	      or NONE to signify a left-unary or right-unary operator. The op‐
	      erand 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  cor‐
	      rect,  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.

	      The index method's support procedure number for a function asso‐
	      ciated with the operator class.

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

	      The parameter data type(s) of the function.

	      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

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

       Because	the index machinery does not check access permissions on func‐
       tions 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 useful
       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 effi‐
       cient handling of cases where an operator might or might not be lossy.

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

       CREATE OPERATOR CLASS gist__int_ops
	       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);

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

       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	  2013-10-08	      CREATE OPERATOR CLASS(7)

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