CREATE_OPERATOR_CLASS(7)

1CREATE OPERATOR CLASS(7)PostgreSQL 9.2.24 DocumentationCREATE OPERATOR CLASS(7)
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NAME

6       CREATE_OPERATOR_CLASS - define a new operator class
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SYNOPSIS

9       CREATE OPERATOR CLASS name [ DEFAULT ] FOR TYPE data_type
10         USING index_method [ FAMILY family_name ] AS
11         {  OPERATOR strategy_number operator_name [ ( op_type, op_type ) ] [ FOR SEARCH | FOR ORDER BY sort_family_name ]
12          | FUNCTION support_number [ ( op_type [ , op_type ] ) ] function_name ( argument_type [, ...] )
13          | STORAGE storage_type
14         } [, ... ]
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DESCRIPTION

17       CREATE OPERATOR CLASS creates a new operator class. An operator class
18       defines how a particular data type can be used with an index. The
19       operator class specifies that certain operators will fill particular
20       roles or “strategies” for this data type and this index method. The
21       operator class also specifies the support procedures to be used by the
22       index method when the operator class is selected for an index column.
23       All the operators and functions used by an operator class must be
24       defined before the operator class can be created.
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26       If a schema name is given then the operator class is created in the
27       specified schema. Otherwise it is created in the current schema. Two
28       operator classes in the same schema can have the same name only if they
29       are for different index methods.
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31       The user who defines an operator class becomes its owner. Presently,
32       the creating user must be a superuser. (This restriction is made
33       because an erroneous operator class definition could confuse or even
34       crash the server.)
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36       CREATE OPERATOR CLASS does not presently check whether the operator
37       class definition includes all the operators and functions required by
38       the index method, nor whether the operators and functions form a
39       self-consistent set. It is the user's responsibility to define a valid
40       operator class.
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42       Related operator classes can be grouped into operator families. To add
43       a new operator class to an existing family, specify the FAMILY option
44       in CREATE OPERATOR CLASS. Without this option, the new class is placed
45       into a family named the same as the new class (creating that family if
46       it doesn't already exist).
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48       Refer to Section 35.14, “Interfacing Extensions To Indexes”, in the
49       documentation for further information.
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PARAMETERS

52       name
53           The name of the operator class to be created. The name can be
54           schema-qualified.
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56       DEFAULT
57           If present, the operator class will become the default operator
58           class for its data type. At most one operator class can be the
59           default for a specific data type and index method.
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61       data_type
62           The column data type that this operator class is for.
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64       index_method
65           The name of the index method this operator class is for.
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67       family_name
68           The name of the existing operator family to add this operator class
69           to. If not specified, a family named the same as the operator class
70           is used (creating it, if it doesn't already exist).
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72       strategy_number
73           The index method's strategy number for an operator associated with
74           the operator class.
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76       operator_name
77           The name (optionally schema-qualified) of an operator associated
78           with the operator class.
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80       op_type
81           In an OPERATOR clause, the operand data type(s) of the operator, or
82           NONE to signify a left-unary or right-unary operator. The operand
83           data types can be omitted in the normal case where they are the
84           same as the operator class's data type.
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86           In a FUNCTION clause, the operand data type(s) the function is
87           intended to support, if different from the input data type(s) of
88           the function (for B-tree comparison functions and hash functions)
89           or the class's data type (for B-tree sort support functions and all
90           functions in GiST, SP-GiST and GIN operator classes). These
91           defaults are correct, and so op_type need not be specified in
92           FUNCTION clauses, except for the case of a B-tree sort support
93           function that is meant to support cross-data-type comparisons.
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95       sort_family_name
96           The name (optionally schema-qualified) of an existing btree
97           operator family that describes the sort ordering associated with an
98           ordering operator.
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100           If neither FOR SEARCH nor FOR ORDER BY is specified, FOR SEARCH is
101           the default.
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103       support_number
104           The index method's support procedure number for a function
105           associated with the operator class.
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107       function_name
108           The name (optionally schema-qualified) of a function that is an
109           index method support procedure for the operator class.
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111       argument_type
112           The parameter data type(s) of the function.
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114       storage_type
115           The data type actually stored in the index. Normally this is the
116           same as the column data type, but some index methods (currently
117           GiST and GIN) allow it to be different. The STORAGE clause must be
118           omitted unless the index method allows a different type to be used.
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120       The OPERATOR, FUNCTION, and STORAGE clauses can appear in any order.
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NOTES

123       Because the index machinery does not check access permissions on
124       functions before using them, including a function or operator in an
125       operator class is tantamount to granting public execute permission on
126       it. This is usually not an issue for the sorts of functions that are
127       useful in an operator class.
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129       The operators should not be defined by SQL functions. A SQL function is
130       likely to be inlined into the calling query, which will prevent the
131       optimizer from recognizing that the query matches an index.
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133       Before PostgreSQL 8.4, the OPERATOR clause could include a RECHECK
134       option. This is no longer supported because whether an index operator
135       is “lossy” is now determined on-the-fly at run time. This allows
136       efficient handling of cases where an operator might or might not be
137       lossy.
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EXAMPLES

140       The following example command defines a GiST index operator class for
141       the data type _int4 (array of int4). See the intarray module for the
142       complete example.
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144           CREATE OPERATOR CLASS gist__int_ops
145               DEFAULT FOR TYPE _int4 USING gist AS
146                   OPERATOR        3       &&,
147                   OPERATOR        6       = (anyarray, anyarray),
148                   OPERATOR        7       @>,
149                   OPERATOR        8       <@,
150                   OPERATOR        20      @@ (_int4, query_int),
151                   FUNCTION        1       g_int_consistent (internal, _int4, int, oid, internal),
152                   FUNCTION        2       g_int_union (internal, internal),
153                   FUNCTION        3       g_int_compress (internal),
154                   FUNCTION        4       g_int_decompress (internal),
155                   FUNCTION        5       g_int_penalty (internal, internal, internal),
156                   FUNCTION        6       g_int_picksplit (internal, internal),
157                   FUNCTION        7       g_int_same (_int4, _int4, internal);
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COMPATIBILITY

160       CREATE OPERATOR CLASS is a PostgreSQL extension. There is no CREATE
161       OPERATOR CLASS statement in the SQL standard.
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