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CREATE CONVERSION(7)	 PostgreSQL 17.5 Documentation	  CREATE CONVERSION(7)

NAME
       CREATE_CONVERSION - define a new	encoding conversion

SYNOPSIS
       CREATE [	DEFAULT	] CONVERSION name
	   FOR source_encoding TO dest_encoding	FROM function_name

DESCRIPTION
       CREATE CONVERSION defines a new conversion between two character	set
       encodings.

       Conversions that	are marked DEFAULT can be used for automatic encoding
       conversion between client and server. To	support	that usage, 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	EXECUTE	privilege on
       the function and	CREATE privilege 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.

       name
	   The name of the conversion. The conversion name can 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.

       dest_encoding
	   The destination encoding name.

       function_name
	   The function	used to	perform	the conversion.	The function name can
	   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)
		   internal, --	destination (fill with a null terminated C string)
		   integer,  --	source string length
		   boolean   --	if true, don't throw an	error if conversion fails
	       ) RETURNS integer;

	   The return value is the number of source bytes that were
	   successfully	converted. If the last argument	is false, the function
	   must	throw an error on invalid input, and the return	value is
	   always equal	to the source string length.

NOTES
       Neither the source nor the destination encoding can be SQL_ASCII, as
       the server's behavior for cases involving the SQL_ASCII "encoding" is
       hard-wired.

       Use DROP	CONVERSION to remove user-defined conversions.

       The privileges required to create a conversion might be changed in a
       future release.

EXAMPLES
       To create a conversion from encoding UTF8 to LATIN1 using myfunc:

	   CREATE CONVERSION myconv FOR	'UTF8' TO 'LATIN1' FROM	myfunc;

COMPATIBILITY
       CREATE CONVERSION is a PostgreSQL extension. There is no	CREATE
       CONVERSION statement in the SQL standard, but a CREATE TRANSLATION
       statement that is very similar in purpose and syntax.

SEE ALSO
       ALTER CONVERSION	(ALTER_CONVERSION(7)), CREATE FUNCTION
       (CREATE_FUNCTION(7)), DROP CONVERSION (DROP_CONVERSION(7))

PostgreSQL 17.5			     2025		  CREATE CONVERSION(7)

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