Function LookupParallelWorkerFunction

src/backend/access/transam/parallel.c:1628–1652

* Look up (and possibly load) a parallel worker entry point function. * * For functions contained in the core code, we use library name "postgres" * and consult the InternalParallelWorkers array. External functions are * looked up, and loaded if necessary, using load_external_function(). * * The point of this is to pass function names as strings across process * boundaries. We can't pass

 * but that raises portability issues that are not worth addressing now.
 */
static parallel_worker_main_type
LookupParallelWorkerFunction(const char *libraryname, const char *funcname)
{
	/*
	 * If the function is to be loaded from postgres itself, search the
	 * InternalParallelWorkers array.
	 */
	if (strcmp(libraryname, "postgres") == 0)
	{
		int			i;

		for (i = 0; i < lengthof(InternalParallelWorkers); i++)
		{
			if (strcmp(InternalParallelWorkers[i].fn_name, funcname) == 0)
				return InternalParallelWorkers[i].fn_addr;
		}

		/* We can only reach this by programming error. */
		elog(ERROR, "internal function \"%s\" not found", funcname);
	}

	/* Otherwise load from external library. */
	return (parallel_worker_main_type)
		load_external_function(libraryname, funcname, true, NULL);
}

void
InitGpParallelDSMHash(void)