Compiling your C++ library

GNU g++ is the only supported compiler for compiling UDx libraries.

GNU g++ is the only supported compiler for compiling UDx libraries. Always compile your UDx code on the same version of Linux that you use on your Vertica cluster.

When compiling your library, you must always:

  • Compile with a -std flag value of c++11 or later.

  • Pass the -shared and -fPIC flags to the linker. The simplest method is to just pass these flags to g++ when you compile and link your library.

  • Use the -Wno-unused-value flag to suppress warnings when macro arguments are not used. If you do not use this flag, you may get "left-hand operand of comma has no effect" warnings.

  • Compile sdk/include/Vertica.cpp and link it into your library. This file contains support routines that help your UDx communicate with Vertica. The easiest way to do this is to include it in the g++ command to compile your library. Vertica supplies this file as C++ source rather than a library to limit library compatibility issues.

  • Add the Vertica SDK include directory in the include search path using the g++ -I flag.

The SDK examples include a working makefile. See Downloading and running UDx example code.

Example of compiling a UDx

The following command compiles a UDx contained in a single source file named MyUDx.cpp into a shared library named

g++ -I /opt/vertica/sdk/include -Wall -shared -Wno-unused-value \
      -fPIC -o MyUDx.cpp /opt/vertica/sdk/include/Vertica.cpp

After you debug your UDx, you are ready to deploy it. Recompile your UDx using the -O3 flag to enable compiler optimization.

You can add additional source files to your library by adding them to the command line. You can also compile them separately and then link them together.

Handling external libraries

You must link your UDx library to any supporting libraries that your UDx code relies on.These libraries might be either ones you developed or others provided by third parties. You have two options for linking:

  • Statically link the support libraries into your UDx. The benefit of this method is that your UDx library does not rely on external files. Having a single UDx library file simplifies deployment because you just transfer a single file to your Vertica cluster. This method's main drawback is that it increases the size of your UDx library file.

  • Dynamically link the library to your UDx. You must sometimes use dynamic linking if a third-party library does not allow static linking. In this case, you must copy the libraries to your Vertica cluster in addition to your UDx library file.