Linktime recognition of alternative implementations of programmed functionality

A method and apparatus are disclosed for optimizing the runtime behavior of database or other applications by allowing selection of alternative code segments during linking of pre-compiled object modules. A macro-preprocessor inserts a declaration for a global variable in the source code in response to an occurrence of a command of interest. The linker selects object modules for executing other commands based on the presence or absence of the declaration for the global variable in the preprocessed source code. The method and apparatus are useful in implementing programming language statements including non-procedural programming languages such as the Embedded Structured Query Language (ESQL).