CREATE CONVERSION -- define a user-defined conversion
Synopsis
CREATE [DEFAULT] CONVERSION conversion_name
FOR source_encoding TO dest_encoding FROM funcname
Description
CREATE CONVERSION defines a new encoding
conversion. Conversion names may be used in the CONVERT() function
to specify a particular encoding conversion. Also, conversions that
are marked DEFAULT can be used for automatic encoding conversion between
frontend and backend. For this purpose, two conversions, from encoding A to
B AND from encoding B to A, must be defined.
To be able to create a conversion, you must have the execute right
on the function and the create right on the destination schema.
Parameters
DEFAULT
The DEFAULT clause indicates that this conversion
is the default for this particular source to destination
encoding. There should be only one default encoding in a schema
for the encoding pair.
conversion_name
The name of the conversion. The conversion name may be
schema-qualified. If it is not, the conversion is defined in the
current schema. The conversion name must be unique within a
schema.
source_encoding
The source encoding name.
source_encoding
The destination encoding name.
funcname
The function used to perform the conversion. The function name may
be schema-qualified. If it is not, the function will be looked
up in the path.
The function must have the following signature:
conv_proc(
INTEGER, -- source encoding id
INTEGER, -- destination encoding id
CSTRING, -- source string (null terminated C string)
CSTRING, -- destination string (null terminated C string)
INTEGER -- source string length
) returns VOID;
Notes
Use DROP CONVERSION to remove user-defined conversions.
The privileges required to create a conversion may be changed in a future
release.
Examples
To create a conversion from encoding UNICODE to LATIN1 using myfunc:
CREATE CONVERSION myconv FOR 'UNICODE' TO 'LATIN1' FROM myfunc;
Compatibility
CREATE CONVERSION
is a PostgreSQL extension.
There is no CREATE CONVERSION
statement in SQL99.
