Provided by: postgresql-client-8.3_8.3.8-1_i386 bug

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 ) ] [ RECHECK ]
          | 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  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
       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
              operand 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.

       RECHECK
              If present, the index is ‘‘lossy’’ for this operator, and so the
              rows  retrieved using the index must be rechecked to verify that
              they actually satisfy the qualification  clause  involving  this
              operator.

       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
       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.

       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.

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       =       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);

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(l)],         CREATE         OPERATOR        FAMILY
       [create_operator_family(l)],        ALTER        OPERATOR        FAMILY
       [alter_operator_family(l)]