(mysql.info.gz) UDF compiling

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(mysql.info.gz) UDF return values

(mysql.info.gz) Adding UDF

 
 25.2.2.5 Compiling and Installing User-defined Functions
 ........................................................
 
 Files implementing UDFs must be compiled and installed on the host where
 the server runs.  This process is described below for the example UDF
 file `udf_example.cc' that is included in the MySQL source distribution.
 
 The immediately following instructions are for Unix. Instructions for
 Windows are given later in this section.
 
 The `udf_example.cc' file contains the following functions:
 
    * `metaphon()' returns a metaphon string of the string argument.
      This is something like a soundex string, but it's more tuned for
      English.
 
    * `myfunc_double()' returns the sum of the ASCII values of the
      characters in its arguments, divided by the sum of the length of
      its arguments.
 
    * `myfunc_int()' returns the sum of the length of its arguments.
 
    * `sequence([const int])' returns an sequence starting from the given
      number or 1 if no number has been given.
 
    * `lookup()' returns the IP number for a hostname.
 
    * `reverse_lookup()' returns the hostname for an IP number.  The
      function may be called with a string `'xxx.xxx.xxx.xxx'' or four
      numbers.
 
 A dynamically loadable file should be compiled as a sharable object
 file, using a command something like this:
 
      shell> gcc -shared -o udf_example.so udf_example.cc
 
 If you are using `gcc', you should be able to create `udf_example.so'
 with a simpler command:
 
      shell> make udf_example.so
 
 You can easily find out the correct compiler options for your system by
 running this command in the `sql' directory of your MySQL source tree:
 
      shell> make udf_example.o
 
 You should run a compile command similar to the one that `make'
 displays, except that you should remove the `-c' option near the end of
 the line and add `-o udf_example.so' to the end of the line.  (On some
 systems, you may need to leave  the `-c' on the command.)
 
 Once you compile a shared object containing UDFs, you must install it
 and tell MySQL about it. Compiling a shared object from `udf_example.cc'
 produces a file named something like `udf_example.so' (the exact name
 may vary from platform to platform). Copy this file to some directory
 searched by the dynamic linker `ld', such as `/usr/lib' or add the
 directory in which you placed the shared object to the linker
 configuration file (for example, `/etc/ld.so.conf').
 
 On many systems, you can also set the `LD_LIBRARY' or `LD_LIBRARY_PATH'
 environment variable to point at the directory where you have your UDF
 function files. The `dlopen' manual page tells you which variable you
 should use on your system. You should set this in `mysql.server' or
 `mysqld_safe' startup scripts and restart `mysqld'.
 
 On some systems, the `ldconfig' program that configures the dynamic
 linker will not recognize shared objects unless their name begins with
 `lib'. In this case you should rename a file such as `udf_example.so'
 to `libudf_example.so'.
 
 On Windows, you can compile user-defined functions by using the
 following procedure:
 
   1. You will need to obtain the BitKeeper source repository for MySQL
      4.0 or higher.   Installing source tree.
 
   2. In the source repository, look in the
      `VC++Files/examples/udf_example' directory. You will find files
      named `udf_example.def', `udf_example.dsp', and `udf_example.dsw'
      there.
 
   3. In the source repository, look in the `sql' directory. Copy the
      `udf_example.cc' from this directory to the
      `VC++Files/examples/udf_example' directory and rename the file to
      `udf_example.cpp'.
 
   4. Open the `udf_example.dsw' file with Visual Studio VC++ and use it
      to compile the UDFs as a normal project.
 
 
 After the library is installed, notify `mysqld' about the new functions
 with these commands:
 
      mysql> CREATE FUNCTION metaphon RETURNS STRING SONAME 'udf_example.so';
      mysql> CREATE FUNCTION myfunc_double RETURNS REAL SONAME 'udf_example.so';
      mysql> CREATE FUNCTION myfunc_int RETURNS INTEGER SONAME 'udf_example.so';
      mysql> CREATE FUNCTION lookup RETURNS STRING SONAME 'udf_example.so';
      mysql> CREATE FUNCTION reverse_lookup
          ->        RETURNS STRING SONAME 'udf_example.so';
      mysql> CREATE AGGREGATE FUNCTION avgcost
          ->        RETURNS REAL SONAME 'udf_example.so';
 
 Functions can be deleted using `DROP FUNCTION':
 
      mysql> DROP FUNCTION metaphon;
      mysql> DROP FUNCTION myfunc_double;
      mysql> DROP FUNCTION myfunc_int;
      mysql> DROP FUNCTION lookup;
      mysql> DROP FUNCTION reverse_lookup;
      mysql> DROP FUNCTION avgcost;
 
 The `CREATE FUNCTION' and `DROP FUNCTION' statements update the system
 table `func' in the `mysql' database.  The function's name, type and
 shared library name are saved in the table.  You must have the `INSERT'
 and `DELETE' privileges for the `mysql' database to create and drop
 functions.
 
 You should not use `CREATE FUNCTION' to add a function that has
 previously been created.  If you need to reinstall a function, you
 should remove it with `DROP FUNCTION' and then reinstall it with
 `CREATE FUNCTION'.  You would need to do this, for example, if you
 recompile a new version of your function, so that `mysqld' gets the new
 version.  Otherwise, the server will continue to use the old version.
 
 Active functions are reloaded each time the server starts, unless you
 start `mysqld' with the `--skip-grant-tables' option.  In this case, UDF
 initialization is skipped and UDFs are unavailable.  (An active
 function is one that has been loaded with `CREATE FUNCTION' and not
 removed with `DROP FUNCTION'.)
 

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(mysql.info.gz) UDF return values

(mysql.info.gz) Adding UDF