CREATE OPERATOR CLASS(7) PostgreSQL 15.7 DocumentationCREATE OPERATOR CLASS(7)
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 ) ] [ FOR SEARCH | FOR ORDER BY sort_family_name ]
| FUNCTION support_number [ ( op_type [ , op_type ] ) ] function_name ( 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 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 38.16 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 prefix 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, 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
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_number
The index method's support function number for a function
associated with the operator class.
function_name
The name (optionally schema-qualified) of a function that is an
index method support function for the operator class.
argument_type
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
GiST, GIN, SP-GiST 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.
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.
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);
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(7)), CREATE OPERATOR FAMILY
(CREATE_OPERATOR_FAMILY(7)), ALTER OPERATOR FAMILY
(ALTER_OPERATOR_FAMILY(7))
PostgreSQL 15.7 2024 CREATE OPERATOR CLASS(7)
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