ALTER OPERATOR FAMILY
ALTER OPERATOR FAMILY
ALTER OPERATOR FAMILY - change the definition of an operator family
Synopsis
ALTER OPERATOR FAMILYname
USINGindex_method
ADD { OPERATORstrategy_number
operator_name
(op_type
,op_type
) [ FOR SEARCH | FOR ORDER BYsort_family_name
] | FUNCTIONsupport_number
[ (op_type
[ ,op_type
] ) ]function_name
[ (argument_type
[, ...] ) ] } [, ... ] ALTER OPERATOR FAMILYname
USINGindex_method
DROP { OPERATORstrategy_number
(op_type
[ ,op_type
] ) | FUNCTIONsupport_number
(op_type
[ ,op_type
] ) } [, ... ] ALTER OPERATOR FAMILYname
USINGindex_method
RENAME TOnew_name
ALTER OPERATOR FAMILYname
USINGindex_method
OWNER TO {new_owner
| CURRENT_USER | SESSION_USER } ALTER OPERATOR FAMILYname
USINGindex_method
SET SCHEMAnew_schema
Description
ALTER OPERATOR FAMILY
changes the definition of
an operator family. You can add operators and support functions
to the family, remove them from the family,
or change the family's name or owner.
When operators and support functions are added to a family with
ALTER OPERATOR FAMILY
, they are not part of any
specific operator class within the family, but are just
"
loose
"
within the family. This indicates that these operators and functions
are compatible with the family's semantics, but are not required for
correct functioning of any specific index. (Operators and functions
that are so required should be declared as part of an operator class,
instead; see
CREATE OPERATOR CLASS
.)
PostgreSQL
will allow loose members of a
family to be dropped from the family at any time, but members of an
operator class cannot be dropped without dropping the whole class and
any indexes that depend on it.
Typically, single-data-type operators
and functions are part of operator classes because they are needed to
support an index on that specific data type, while cross-data-type
operators and functions are made loose members of the family.
You must be a superuser to use
ALTER OPERATOR FAMILY
.
(This restriction is made because an erroneous operator family definition
could confuse or even crash the server.)
ALTER OPERATOR FAMILY
does not presently check
whether the operator family 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 family.
Refer to Section 38.15 for further information.
Parameters
-
name
-
The name (optionally schema-qualified) of an existing operator family.
-
index_method
-
The name of the index method this operator family is for.
-
strategy_number
-
The index method's strategy number for an operator associated with the operator family.
-
operator_name
-
The name (optionally schema-qualified) of an operator associated with the operator family.
-
op_type
-
In an
OPERATOR
clause, the operand data type(s) of the operator, orNONE
to signify a left-unary or right-unary operator. Unlike the comparable syntax inCREATE OPERATOR CLASS
, the operand data types must always be specified.In an
ADD 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 it is not necessary to specifyop_type
since the function's input data type(s) are always the correct ones to use. For B-tree sort support functions and all functions in GiST, SP-GiST and GIN operator classes, it is necessary to specify the operand data type(s) the function is to be used with.In a
DROP FUNCTION
clause, the operand data type(s) the function is intended to support must be specified. -
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
norFOR 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 family.
-
function_name
-
The name (optionally schema-qualified) of a function that is an index method support function for the operator family. If no argument list is specified, the name must be unique in its schema.
-
argument_type
-
The parameter data type(s) of the function.
-
new_name
-
The new name of the operator family.
-
new_owner
-
The new owner of the operator family.
-
new_schema
-
The new schema for the operator family.
The
OPERATOR
and
FUNCTION
clauses can appear in any order.
Notes
Notice that the
DROP
syntax only specifies the
"
slot
"
in the operator family, by strategy or support number and input data
type(s). The name of the operator or function occupying the slot is not
mentioned. Also, for
DROP FUNCTION
the type(s) to specify
are the input data type(s) the function is intended to support; for
GiST, SP-GiST and GIN indexes this might have nothing to do with the actual
input argument types of the function.
Because the index machinery does not check access permissions on functions before using them, including a function or operator in an operator family 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 family.
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.
Examples
The following example command adds cross-data-type operators and
support functions to an operator family that already contains B-tree
operator classes for data types
int4
and
int2
.
ALTER OPERATOR FAMILY integer_ops USING btree ADD -- int4 vs int2 OPERATOR 1 < (int4, int2) , OPERATOR 2 <= (int4, int2) , OPERATOR 3 = (int4, int2) , OPERATOR 4 >= (int4, int2) , OPERATOR 5 > (int4, int2) , FUNCTION 1 btint42cmp(int4, int2) , -- int2 vs int4 OPERATOR 1 < (int2, int4) , OPERATOR 2 <= (int2, int4) , OPERATOR 3 = (int2, int4) , OPERATOR 4 >= (int2, int4) , OPERATOR 5 > (int2, int4) , FUNCTION 1 btint24cmp(int2, int4) ;
To remove these entries again:
ALTER OPERATOR FAMILY integer_ops USING btree DROP -- int4 vs int2 OPERATOR 1 (int4, int2) , OPERATOR 2 (int4, int2) , OPERATOR 3 (int4, int2) , OPERATOR 4 (int4, int2) , OPERATOR 5 (int4, int2) , FUNCTION 1 (int4, int2) , -- int2 vs int4 OPERATOR 1 (int2, int4) , OPERATOR 2 (int2, int4) , OPERATOR 3 (int2, int4) , OPERATOR 4 (int2, int4) , OPERATOR 5 (int2, int4) , FUNCTION 1 (int2, int4) ;
Compatibility
There is no
ALTER OPERATOR FAMILY
statement in
the SQL standard.