CREATE CONVERSION — define a new encoding conversion
CREATE [ DEFAULT ] CONVERSIONname
FORsource_encoding
TOdest_encoding
FROMfunction_name
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.
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 ) RETURNS void;
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.
To create a conversion from encoding UTF8
to LATIN1
using myfunc
:
CREATE CONVERSION myconv FOR 'UTF8' TO 'LATIN1' FROM myfunc;
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.
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