CREATE CONVERSION

Defines a new encoding conversion.

Synopsis

CREATE [DEFAULT] CONVERSION <name> FOR <source_encoding> TO 
     <dest_encoding> FROM <funcname>

Description

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.

Parameters

DEFAULT : 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 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.

dest_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) internal, -- destination (fill with a null terminated C string) integer -- source string length ) RETURNS void;

Notes

Note that in this release of LightDB-A 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 LightDB-A Database array (coordinatornatornatornator and all segments). This location must also be in the LD_LIBRARY_PATH so that the server can locate the files.

Examples

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

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

Compatibility

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.