|DB2 now supports new collation sequence keywords, IDENTITY_16BIT and SQL_CS_IDENTITY_16BIT, |for Unicode databases. When IDENTITY_16BIT is specified for the CLP CREATE |DATABASE command or SQLEDBDESC.SQLDBCSS is set to SQL_CS_IDENTITY_16BIT in |the sqlecrea() -- Create Database API, all data in the Unicode database |will be collated using the CESU-8 order. CESU-8 is Compatibility Encoding Scheme for UTF-16: 8-Bit, and as of this writing, |its specification is contained in the Draft Unicode Technical Report #26 available |at the Unicode Technical Consortium web site(www.unicode.org). CESU-8 is binary |identical to UTF-8 except for the Unicode supplementary characters, that is, |those characters that are defined outside the 16-bit Basic Multilingual Plane |(BMP or Plane 0). In UTF-8 encoding, a supplementary character is represented |by one 4-byte sequence, but the same character in CESU-8 requires two 3-byte |sequences.
|In a Unicode database, CHAR, VARCHAR, LONG VARCHAR, and CLOB data are stored |in UTF-8, and GRAPHIC, VARGRAPHIC, LONG VARGRAPHIC, and DBCLOB data are stored |in UCS-2. For IDENTITY or SQL_CS_NONE collation, non-supplementary characters |in UTF-8 and UCS-2 have identical binary collation, but supplementary characters |in UTF-8 collate differently from the same characters in UCS-2. IDENTITY_16BIT |or SQL_CS_IDENTITY_16BIT ensures all characters, supplementary and non-supplementary, |in a DB2 Unicode databases have the same binary collation.