Index for Section OPERATOR

Alphabetical listing for C

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CREATE
NAME
  CREATE OPERATOR CLASS - define a new operator class

SYNOPSIS
  CREATE OPERATOR CLASS name [ DEFAULT ] FOR TYPE data_type USING index_method AS
    {  OPERATOR strategy_number operator_name [ ( op_type, op_type ) ] [ RECHECK ]
     | FUNCTION support_number funcname ( argument_type [, ...] )
     | STORAGE storage_type
    } [, ... ]

DESCRIPTION
  CREATE OPERATOR CLASS creates a new operator class.  An operator class
  defines how a particular data type can be used with an index. The operator
  class specifies that certain operators will fill particular roles or
  ``strategies'' for this data type and this index method. The operator class
  also specifies the support procedures to be used by the index method when
  the operator class is selected for an index column. All the operators and
  functions used by an operator class must be defined before the operator
  class is created.

  If a schema name is given then the operator class is created in the
  specified schema. Otherwise it is created in the current schema.  Two
  operator classes in the same schema can have the same name only if they are
  for different index methods.

  The user who defines an operator class becomes its owner. Presently, the
  creating user must be a superuser. (This restriction is made because an
  erroneous operator class definition could confuse or even crash the
  server.)

  CREATE OPERATOR CLASS does not presently check whether the operator class
  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 class.

  Refer to in the documentation for further information.

PARAMETERS
  name The name of the operator class to be created. The name may be schema-
       qualified.

  DEFAULT
       If present, the operator class will become the default operator class
       for its data type. At most one operator class can be the default for a
       specific data type and index method.

  data_type
       The column data type that this operator class is for.

  index_method
       The name of the index method this operator class is for.

  strategy_number
       The index method's strategy number for an operator associated with the
       operator class.

  operator_name
       The name (optionally schema-qualified) of an operator associated with
       the operator class.

  op_type
       The operand data type(s) of an operator, or NONE to signify a left-
       unary or right-unary operator. The operand data types may be omitted
       in the normal case where they are the same as the operator class's
       data type.

  RECHECK
       If present, the index is ``lossy'' for this operator, and so the rows
       retrieved using the index must be rechecked to verify that they
       actually satisfy the qualification clause involving this operator.

  support_number
       The index method's support procedure number for a function associated
       with the operator class.

  funcname
       The name (optionally schema-qualified) of a function that is an index
       method support procedure for the operator class.

  argument_types
       The parameter data type(s) of the function.

  storage_type
       The data type actually stored in the index. Normally this is the same
       as the column data type, but some index methods (GIN and GiST for now)
       allow it to be different. The STORAGE clause must be omitted unless
       the index method allows a different type to be used.

  The OPERATOR, FUNCTION, and STORAGE clauses may appear in any order.

NOTES
  Because the index machinery does not check access permissions on functions
  before using them, including a function or operator in an operator class 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 class.

  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.

EXAMPLES
  The following example command defines a GiST index operator class for the
  data type _int4 (array of int4). See contrib/intarray/ for the complete
  example.

  CREATE OPERATOR CLASS gist__int_ops
      DEFAULT FOR TYPE _int4 USING gist AS
	  OPERATOR	  3	  &&,
	  OPERATOR	  6	  =	  RECHECK,
	  OPERATOR	  7	  @>,
	  OPERATOR	  8	  <@,
	  OPERATOR	  20	  @@ (_int4, query_int),
	  FUNCTION	  1	  g_int_consistent (internal, _int4, int4),
	  FUNCTION	  2	  g_int_union (bytea, internal),
	  FUNCTION	  3	  g_int_compress (internal),
	  FUNCTION	  4	  g_int_decompress (internal),
	  FUNCTION	  5	  g_int_penalty (internal, internal, internal),
	  FUNCTION	  6	  g_int_picksplit (internal, internal),
	  FUNCTION	  7	  g_int_same (_int4, _int4, internal);

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

SEE ALSO
  ALTER OPERATOR CLASS [alter_operator_class(5)], DROP OPERATOR CLASS
  [drop_operator_class(l)]

Index for Section OPERATOR

Alphabetical listing for C

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