Index for Section OPERATOR

Alphabetical listing for C

Bottom of page

CREATE
NAME
  CREATE OPERATOR - define a new operator

SYNOPSIS
  CREATE OPERATOR name (
      PROCEDURE = funcname
      [, LEFTARG = lefttype ] [, RIGHTARG = righttype ]
      [, COMMUTATOR = com_op ] [, NEGATOR = neg_op ]
      [, RESTRICT = res_proc ] [, JOIN = join_proc ]
      [, HASHES ] [, MERGES ]
      [, SORT1 = left_sort_op ] [, SORT2 = right_sort_op ]
      [, LTCMP = less_than_op ] [, GTCMP = greater_than_op ]
  )

DESCRIPTION
  CREATE OPERATOR defines a new operator, name. The user who defines an
  operator becomes its owner. If a schema name is given then the operator is
  created in the specified schema. Otherwise it is created in the current
  schema.

  The operator name is a sequence of up to NAMEDATALEN-1 (63 by default)
  characters from the following list:

  + - * / < > = ~ ! @ # % ^ & | ` ?

  There are a few restrictions on your choice of name:

  · -- and /* cannot appear anywhere in an operator name, since they will be
    taken as the start of a comment.

  · A multicharacter operator name cannot end in + or -, unless the name also
    contains at least one of these characters:

    ~ ! @ # % ^ & | ` ?

    For example, @- is an allowed operator name, but *- is not.	 This
    restriction allows PostgreSQL to parse SQL-compliant commands without
    requiring spaces between tokens.

  The operator != is mapped to <> on input, so these two names are always
  equivalent.

  At least one of LEFTARG and RIGHTARG must be defined. For binary operators,
  both must be defined. For right unary operators, only LEFTARG should be
  defined, while for left unary operators only RIGHTARG should be defined.

  The funcname procedure must have been previously defined using CREATE
  FUNCTION and must be defined to accept the correct number of arguments
  (either one or two) of the indicated types.

  The other clauses specify optional operator optimization clauses.  Their
  meaning is detailed in in the documentation.

PARAMETERS
  name The name of the operator to be defined. See above for allowable
       characters. The name may be schema-qualified, for example CREATE
       OPERATOR myschema.+ (...). If not, then the operator is created in the
       current schema. Two operators in the same schema can have the same
       name if they operate on different data types. This is called
       overloading.

  funcname
       The function used to implement this operator.

  lefttype
       The data type of the operator's left operand, if any.  This option
       would be omitted for a left-unary operator.

  righttype
       The data type of the operator's right operand, if any.  This option
       would be omitted for a right-unary operator.

  com_op
       The commutator of this operator.

  neg_op
       The negator of this operator.

  res_proc
       The restriction selectivity estimator function for this operator.

  join_proc
       The join selectivity estimator function for this operator.

  HASHES
       Indicates this operator can support a hash join.

  MERGES
       Indicates this operator can support a merge join.

  left_sort_op
       If this operator can support a merge join, the less-than operator that
       sorts the left-hand data type of this operator.

  right_sort_op
       If this operator can support a merge join, the less-than operator that
       sorts the right-hand data type of this operator.

  less_than_op
       If this operator can support a merge join, the less-than operator that
       compares the input data types of this operator.

  greater_than_op
       If this operator can support a merge join, the greater-than operator
       that compares the input data types of this operator.

  To give a schema-qualified operator name in com_op or the other optional
  arguments, use the OPERATOR() syntax, for example

  COMMUTATOR = OPERATOR(myschema.===) ,

NOTES
  Refer to in the documentation for further information.

  Use DROP OPERATOR [drop_operator(5)] to delete user-defined operators from
  a database. Use ALTER OPERATOR [alter_operator(5)] to modify operators in a
  database.

EXAMPLES
  The following command defines a new operator, area-equality, for the data
  type box:

  CREATE OPERATOR === (
      LEFTARG = box,
      RIGHTARG = box,
      PROCEDURE = area_equal_procedure,
      COMMUTATOR = ===,
      NEGATOR = !==,
      RESTRICT = area_restriction_procedure,
      JOIN = area_join_procedure,
      HASHES,
      SORT1 = <<<,
      SORT2 = <<<
      -- Since sort operators were given, MERGES is implied.
      -- LTCMP and GTCMP are assumed to be < and > respectively
  );

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

SEE ALSO
  ALTER OPERATOR [alter_operator(5)], CREATE OPERATOR CLASS
  [create_operator_class(l)], DROP OPERATOR [drop_operator(l)]

Index for Section OPERATOR

Alphabetical listing for C

Top of page