create_operator_class(7)

—

NAME

CREATE_OPERATOR_CLASS - define a new operator class

SYNOPSIS

bash

CREATE OPERATOR CLASS \nname\n [ DEFAULT ] FOR TYPE \ndata_type\n
\n
  USING \nindex_method\n [ FAMILY \nfamily_name\n ] AS
\n
  {  OPERATOR \nstrategy_number\n \noperator_name\n [ ( \nop_type\n, \nop_type\n ) ] [ FOR SEARCH | FOR ORDER BY \nsort_family_name\n ]
\n
   | FUNCTION \nsupport_number\n [ ( \nop_type\n [ , \nop_type\n ] ) ] \nfunction_name\n ( \nargument_type\n [, ...] )
\n
   | STORAGE \nstorage_type\n
\n
  } [, ... ]

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 36.16 for further information.

PARAMETERS

name

DEFAULT

data_type

index_method

family_name

strategy_number

operator_name

op_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, B-tree equal image 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

If neither FOR SEARCH nor FOR ORDER BY is specified, FOR SEARCH is the default.

support_number

function_name

argument_type

storage_type

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. An 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.

EXAMPLES

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.

bash

CREATE OPERATOR CLASS gist__int_ops
\n
    DEFAULT FOR TYPE _int4 USING gist AS
\n
        OPERATOR        3       &&,
\n
        OPERATOR        6       = (anyarray, anyarray),
\n
        OPERATOR        7       @>,
\n
        OPERATOR        8       <@,
\n
        OPERATOR        20      @@ (_int4, query_int),
\n
        FUNCTION        1       g_int_consistent (internal, _int4, smallint, oid, internal),
\n
        FUNCTION        2       g_int_union (internal, internal),
\n
        FUNCTION        3       g_int_compress (internal),
\n
        FUNCTION        4       g_int_decompress (internal),
\n
        FUNCTION        5       g_int_penalty (internal, internal, internal),
\n
        FUNCTION        6       g_int_picksplit (internal, internal),
\n
        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.