This section discusses the procedure for adding a character set to MySQL. The proper procedure depends on whether the character set is simple or complex:
If the character set does not need special string collating routines for sorting and does not need multibyte character support, it is simple.
If the character set needs either of those features, it is complex.
For example, greek
and swe7
are simple character sets, whereas big5
and
czech
are complex character sets.
To use the following instructions, you must have a MySQL source
distribution. In the instructions,
MYSET
represents the name of the
character set that you want to add.
Add a
<charset>
element forMYSET
to thesql/share/charsets/Index.xml
file. Use the existing contents in the file as a guide to adding new contents. A partial listing for thelatin1
<charset>
element follows:<charset name="latin1"> <family>Western</family> <description>cp1252 West European</description> ... <collation name="latin1_swedish_ci" id="8" order="Finnish, Swedish"> <flag>primary</flag> <flag>compiled</flag> </collation> <collation name="latin1_danish_ci" id="15" order="Danish"/> ... <collation name="latin1_bin" id="47" order="Binary"> <flag>binary</flag> <flag>compiled</flag> </collation> ... </charset>
The
<charset>
element must list all the collations for the character set. These must include at least a binary collation and a default (primary) collation. The default collation is often named using a suffix ofgeneral_ci
(general, case-insensitive). It is possible for the binary collation to be the default collation, but usually they are different. The default collation should have aprimary
flag. The binary collation should have abinary
flag.You must assign a unique ID number to each collation. The range of IDs from 1024 to 2047 is reserved for user-defined collations. To find the maximum of the currently used collation IDs, use this query:
SELECT MAX(ID) FROM INFORMATION_SCHEMA.COLLATIONS;
This step depends on whether you are adding a simple or complex character set. A simple character set requires only a configuration file, whereas a complex character set requires C source file that defines collation functions, multibyte functions, or both.
For a simple character set, create a configuration file,
, that describes the character set properties. Create this file in theMYSET
.xmlsql/share/charsets
directory. You can use a copy oflatin1.xml
as the basis for this file. The syntax for the file is very simple:Comments are written as ordinary XML comments (
<!--
).text
-->Words within
<map>
array elements are separated by arbitrary amounts of whitespace.Each word within
<map>
array elements must be a number in hexadecimal format.The
<map>
array element for the<ctype>
element has 257 words. The other<map>
array elements after that have 256 words. See Section 12.13.1, “Character Definition Arrays”.For each collation listed in the
<charset>
element for the character set inIndex.xml
,
must contain aMYSET
.xml<collation>
element that defines the character ordering.
For a complex character set, create a C source file that describes the character set properties and defines the support routines necessary to properly perform operations on the character set:
Create the file
ctype-
in theMYSET
.cstrings
directory. Look at one of the existingctype-*.c
files (such asctype-big5.c
) to see what needs to be defined. The arrays in your file must have names likectype_
,MYSET
to_lower_
, and so on. These correspond to the arrays for a simple character set. See Section 12.13.1, “Character Definition Arrays”.MYSET
For each
<collation>
element listed in the<charset>
element for the character set inIndex.xml
, thectype-
file must provide an implementation of the collation.MYSET
.cIf the character set requires string collating functions, see Section 12.13.2, “String Collating Support for Complex Character Sets”.
If the character set requires multibyte character support, see Section 12.13.3, “Multi-Byte Character Support for Complex Character Sets”.
Modify the configuration information. Use the existing configuration information as a guide to adding information for
MYSYS
. The example here assumes that the character set has default and binary collations, but more lines are needed ifMYSET
has additional collations.Edit
mysys/charset-def.c
, and “register” the collations for the new character set.Add these lines to the “declaration” section:
#ifdef HAVE_CHARSET_MYSET extern CHARSET_INFO my_charset_MYSET_general_ci; extern CHARSET_INFO my_charset_MYSET_bin; #endif
Add these lines to the “registration” section:
#ifdef HAVE_CHARSET_MYSET add_compiled_collation(&my_charset_MYSET_general_ci); add_compiled_collation(&my_charset_MYSET_bin); #endif
If the character set uses
ctype-
, editMYSET
.cstrings/CMakeLists.txt
and addctype-
to the definition of theMYSET
.cSTRINGS_SOURCES
variable.Edit
cmake/character_sets.cmake
:Add
MYSET
to the value of withCHARSETS_AVAILABLE
in alphabetic order.Add
MYSET
to the value ofCHARSETS_COMPLEX
in alphabetic order. This is needed even for simple character sets, so that CMake can recognize-DDEFAULT_CHARSET=
.MYSET
Reconfigure, recompile, and test.