CREATE_OPERATOR(7)

1CREATE OPERATOR(7)       PostgreSQL 10.7 Documentation      CREATE OPERATOR(7)
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NAME

6       CREATE_OPERATOR - define a new operator
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SYNOPSIS

9       CREATE OPERATOR name (
10           PROCEDURE = function_name
11           [, LEFTARG = left_type ] [, RIGHTARG = right_type ]
12           [, COMMUTATOR = com_op ] [, NEGATOR = neg_op ]
13           [, RESTRICT = res_proc ] [, JOIN = join_proc ]
14           [, HASHES ] [, MERGES ]
15       )
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DESCRIPTION

18       CREATE OPERATOR defines a new operator, name. The user who defines an
19       operator becomes its owner. If a schema name is given then the operator
20       is created in the specified schema. Otherwise it is created in the
21       current schema.
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23       The operator name is a sequence of up to NAMEDATALEN-1 (63 by default)
24       characters from the following list:
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26           + - * / < > = ~ ! @ # % ^ & | ` ?
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28       There are a few restrictions on your choice of name:
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30       ·   -- and /* cannot appear anywhere in an operator name, since they
31           will be taken as the start of a comment.
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33       ·   A multicharacter operator name cannot end in + or -, unless the
34           name also contains at least one of these characters:
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36               ~ ! @ # % ^ & | ` ?
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38           For example, @- is an allowed operator name, but *- is not. This
39           restriction allows PostgreSQL to parse SQL-compliant commands
40           without requiring spaces between tokens.
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42       ·   The use of => as an operator name is deprecated. It may be
43           disallowed altogether in a future release.
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45       The operator != is mapped to <> on input, so these two names are always
46       equivalent.
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48       At least one of LEFTARG and RIGHTARG must be defined. For binary
49       operators, both must be defined. For right unary operators, only
50       LEFTARG should be defined, while for left unary operators only RIGHTARG
51       should be defined.
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53       The function_name procedure must have been previously defined using
54       CREATE FUNCTION and must be defined to accept the correct number of
55       arguments (either one or two) of the indicated types.
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57       The other clauses specify optional operator optimization clauses. Their
58       meaning is detailed in Section 37.13.
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60       To be able to create an operator, you must have USAGE privilege on the
61       argument types and the return type, as well as EXECUTE privilege on the
62       underlying function. If a commutator or negator operator is specified,
63       you must own these operators.
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PARAMETERS

66       name
67           The name of the operator to be defined. See above for allowable
68           characters. The name can be schema-qualified, for example CREATE
69           OPERATOR myschema.+ (...). If not, then the operator is created in
70           the current schema. Two operators in the same schema can have the
71           same name if they operate on different data types. This is called
72           overloading.
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74       function_name
75           The function used to implement this operator.
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77       left_type
78           The data type of the operator's left operand, if any. This option
79           would be omitted for a left-unary operator.
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81       right_type
82           The data type of the operator's right operand, if any. This option
83           would be omitted for a right-unary operator.
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85       com_op
86           The commutator of this operator.
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88       neg_op
89           The negator of this operator.
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91       res_proc
92           The restriction selectivity estimator function for this operator.
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94       join_proc
95           The join selectivity estimator function for this operator.
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97       HASHES
98           Indicates this operator can support a hash join.
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100       MERGES
101           Indicates this operator can support a merge join.
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103       To give a schema-qualified operator name in com_op or the other
104       optional arguments, use the OPERATOR() syntax, for example:
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106           COMMUTATOR = OPERATOR(myschema.===) ,
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NOTES

109       Refer to Section 37.12 for further information.
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111       It is not possible to specify an operator's lexical precedence in
112       CREATE OPERATOR, because the parser's precedence behavior is
113       hard-wired. See Section 4.1.6 for precedence details.
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115       The obsolete options SORT1, SORT2, LTCMP, and GTCMP were formerly used
116       to specify the names of sort operators associated with a merge-joinable
117       operator. This is no longer necessary, since information about
118       associated operators is found by looking at B-tree operator families
119       instead. If one of these options is given, it is ignored except for
120       implicitly setting MERGES true.
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122       Use DROP OPERATOR (DROP_OPERATOR(7)) to delete user-defined operators
123       from a database. Use ALTER OPERATOR (ALTER_OPERATOR(7)) to modify
124       operators in a database.
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EXAMPLES

127       The following command defines a new operator, area-equality, for the
128       data type box:
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130           CREATE OPERATOR === (
131               LEFTARG = box,
132               RIGHTARG = box,
133               PROCEDURE = area_equal_procedure,
134               COMMUTATOR = ===,
135               NEGATOR = !==,
136               RESTRICT = area_restriction_procedure,
137               JOIN = area_join_procedure,
138               HASHES, MERGES
139           );
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COMPATIBILITY

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