Defines a new encoding conversion.
CREATE [DEFAULT] CONVERSION <name> FOR <source_encoding> TO <dest_encoding> FROM <funcname>
CREATE CONVERSION defines a new conversion between character set encodings. 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 client and server. For this purpose, two conversions, from encoding A to B and from encoding B to A, must be defined.
To create a conversion, you must have
EXECUTE privilege on the function and
CREATE privilege on the destination schema.
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) internal, -- destination (fill with a null terminated C string) integer -- source string length ) RETURNS void;
Note that in this release of Greenplum Database, user-defined functions used in a user-defined conversion must be defined as
IMMUTABLE. Any compiled code (shared library files) for custom functions must be placed in the same location on every host in your Greenplum Database array (master and all segments). This location must also be in the
LD_LIBRARY_PATH so that the server can locate the files.
To create a conversion from encoding
CREATE CONVERSION myconv FOR 'UTF8' TO 'LATIN1' FROM myfunc;
There is no
CREATE CONVERSION statement in the SQL standard, but there is a
CREATE TRANSLATION statement that is very similar in purpose and syntax.
Parent topic: SQL Commands