I should point out my previous article on the subject since there are parts of it that are still applicable.

This is likely applicable to other MySQL UDFs as well but I haven’t tried.

I used the MySQL 5.1.57 x64 version for my system and I downloaded the zip archive rather than the installer. (Note that the server can still be installed as a service but you will need to run the cmd.exe program as an administrator in order to run the command line installation process.)

I also used Microsoft Visual C++ Express 2010 for this and my Windows version is Windows 7 Ultimate x64.

In addition to VS C++, you will also need the Windows SDK for Windows 7 which you can download here. This addition is critical since it contains the x64 compiler and other tools.

When you have everything installed, follow the instructions on Roland Bouman’s blog post about building UDFs on Windows but stop before building and installing the function then follow these steps to 64bit glory (if you are specifically using udf_median, you might also be interested in this post):

1. Right-click on the project (not the solution), choose “Properties”. At the top of the dialog, from the “Configuration” dropdown, select “All Configurations”.
   
2. Next expand “Configuration Properties” then select “General”. In the field on the right labeled “Platform Toolset” make sure the value “Windows7.1SDK” is selected
   
3. Now let’s make it x64. At the top of the dialog box, click on the “Configuration Manager” button.
   
4. In the resultant grid, select the “Platform” dropdown and choose “New…”. When the “New Project Platform” comes up, select x64 from the top dropdown then click “OK” then “Close” then close the Properties dialog.
   
5. Now you can try building the project
   
6. If the build is successful, you find the .dll, in my case ufd_median.dll, in the “Debug” or “Release” folder. Put that in the MySQL lib/plugin/ directory
   
7. Install the plugin using SQL like this:
   
CREATE AGGREGATE FUNCTION median RETURNS REAL SONAME 'udf_median.dll';


And that should be it.

Here are a few things that I came across while setting up my project that might be helpful:

1. In one instance the linker reported this error:
   1>LINK : fatal error LNK1104: cannot open file 'kernel32.lib'
   The fix for this was making sure that the “Platform Toolset” in the project configuration properties was set to “Windows7.1SDK”
2. If you get this error:
   ERROR 1126 (HY000): Can't open shared library 'file.dll'
   this can sometimes mean that the .dll wasn’t compiled correctly (i.e. this is what you get when you try to use a 32bit .dll with a 64bit server) or the symbol exports didn’t work. I used the dumpbin program to make sure that the functions that needed to be exported were. Under the “Tools” menu in VC++, select “Visual Studio Command Prompt” then navigate to the directory with your .dll file and run this command:
   dumpbin /exports udf_median.dll
   You should see the exported functions in the output.
3. I did not have to alter any of the C code to make this work even though I saw some comments on Roland’s post indicating that might be necessary.

That’s about it. Feel free to contact me if you have any questions or if the steps didn’t work for you.