CREATE OPERATOR CLASS — define a new operator class
CREATE OPERATOR CLASSname[ DEFAULT ] FOR TYPEdata_typeUSINGindex_method[ FAMILYfamily_name] AS { OPERATORstrategy_numberoperator_name[ (op_type,op_type) ] [ FOR SEARCH | FOR ORDER BYsort_family_name] | FUNCTIONsupport_number[ (op_type[ ,op_type] ) ]function_name(argument_type[, ...] ) | STORAGEstorage_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 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 functions 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 Section 37.16 for further information.
nameThe name of the operator class to be created. The name can be schema-qualified.
DEFAULTIf 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_typeThe column data type that this operator class is for.
index_methodThe name of the index method this operator class is for.
family_nameThe 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_numberThe index method's strategy number for an operator associated with the operator class.
operator_nameThe 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 comparison functions
      and hash functions)
      or the class's data type (for B-tree sort support functions and all
      functions in GiST, SP-GiST, GIN and BRIN operator classes).  These defaults
      are correct, and so op_type need not be specified in
      FUNCTION clauses, except for the case of a B-tree sort
      support function that is meant to support cross-data-type comparisons.
     
sort_family_name
      The name (optionally schema-qualified) of an existing btree operator
      family that describes the sort ordering associated with an ordering
      operator.
     
      If neither FOR SEARCH nor FOR ORDER BY is
      specified, FOR SEARCH is the default.
     
support_numberThe index method's support function number for a function associated with the operator class.
function_nameThe name (optionally schema-qualified) of a function that is an index method support function for the operator class.
argument_typeThe 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 GiST, GIN and BRIN) allow it to be different.  The
      STORAGE clause must be omitted unless the index
      method allows a different type to be used.
      If the column data_type is specified
      as anyarray, the storage_type
      can be declared as anyelement to indicate that the index
      entries are members of the element type belonging to the actual array
      type that each particular index is created for.
     
   The OPERATOR, FUNCTION, and STORAGE
   clauses can appear in any order.
  
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.
   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 run time.  This allows efficient 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 the
   intarray module 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, smallint, 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.