create_operator(7)

1CREATE OPERATOR(7)               SQL Commands               CREATE OPERATOR(7)
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NAME

6       CREATE OPERATOR - define a new operator
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SYNOPSIS

10       CREATE OPERATOR name (
11           PROCEDURE = funcname
12           [, LEFTARG = lefttype ] [, RIGHTARG = righttype ]
13           [, COMMUTATOR = com_op ] [, NEGATOR = neg_op ]
14           [, RESTRICT = res_proc ] [, JOIN = join_proc ]
15           [, HASHES ] [, MERGES ]
16       )
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DESCRIPTION

20       CREATE  OPERATOR  defines a new operator, name. The user who defines an
21       operator becomes its owner. If a schema name is given then the operator
22       is created in the specified schema. Otherwise it is created in the cur‐
23       rent schema.
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25       The operator name is a sequence of up to NAMEDATALEN-1 (63 by  default)
26       characters from the following list:
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28       + - * / < > = ~ ! @ # % ^ & | ` ?
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30       There are a few restrictions on your choice of name:
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32       · -- and /* cannot appear anywhere in an operator name, since they will
33         be taken as the start of a comment.
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35       · A multicharacter operator name cannot end in + or -, unless the  name
36         also contains at least one of these characters:
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38         ~ ! @ # % ^ & | ` ?
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40         For  example,  @-  is  an allowed operator name, but *- is not.  This
41         restriction allows PostgreSQL to parse SQL-compliant commands without
42         requiring spaces between tokens.
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44       The operator != is mapped to <> on input, so these two names are always
45       equivalent.
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47       At least one of LEFTARG and RIGHTARG must be defined. For binary opera‐
48       tors,  both  must  be  defined. For right unary operators, only LEFTARG
49       should be defined, while for left unary operators only RIGHTARG  should
50       be defined.
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52       The  funcname  procedure must have been previously defined using CREATE
53       FUNCTION and must be defined to accept the correct number of  arguments
54       (either one or two) of the indicated types.
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56       The  other  clauses  specify  optional  operator  optimization clauses.
57       Their meaning is detailed in in the documentation.
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PARAMETERS

60       name   The name of the operator to be defined. See above for  allowable
61              characters. The name can be schema-qualified, for example CREATE
62              OPERATOR myschema.+ (...). If not, then the operator is  created
63              in the current schema. Two operators in the same schema can have
64              the same name if they operate on different data types.  This  is
65              called overloading.
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67       funcname
68              The function used to implement this operator.
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70       lefttype
71              The  data  type  of  the  operator's left operand, if any.  This
72              option would be omitted for a left-unary operator.
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74       righttype
75              The data type of the operator's right  operand,  if  any.   This
76              option would be omitted for a right-unary operator.
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78       com_op The commutator of this operator.
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80       neg_op The negator of this operator.
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82       res_proc
83              The  restriction  selectivity estimator function for this opera‐
84              tor.
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86       join_proc
87              The join selectivity estimator function for this operator.
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89       HASHES Indicates this operator can support a hash join.
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91       MERGES Indicates this operator can support a merge join.
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93       To give a  schema-qualified  operator  name  in  com_op  or  the  other
94       optional arguments, use the OPERATOR() syntax, for example:
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96       COMMUTATOR = OPERATOR(myschema.===) ,
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NOTES

100       Refer to in the documentation for further information.
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102       The  obsolete options SORT1, SORT2, LTCMP, and GTCMP were formerly used
103       to specify the names of sort operators associated with a merge-joinable
104       operator.  This is no longer necessary, since information about associ‐
105       ated operators is found by looking at B-tree operator families instead.
106       If  one  of these options is given, it is ignored except for implicitly
107       setting MERGES true.
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109       Use DROP OPERATOR [drop_operator(7)] to delete  user-defined  operators
110       from a database. Use ALTER OPERATOR [alter_operator(7)] to modify oper‐
111       ators in a database.
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EXAMPLES

114       The following command defines a new operator,  area-equality,  for  the
115       data type box:
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117       CREATE OPERATOR === (
118           LEFTARG = box,
119           RIGHTARG = box,
120           PROCEDURE = area_equal_procedure,
121           COMMUTATOR = ===,
122           NEGATOR = !==,
123           RESTRICT = area_restriction_procedure,
124           JOIN = area_join_procedure,
125           HASHES, MERGES
126       );
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COMPATIBILITY

130       CREATE  OPERATOR is a PostgreSQL extension. There are no provisions for
131       user-defined operators in the SQL standard.
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