*** a/src/backend/tcop/postgres.c
--- b/src/backend/tcop/postgres.c
***************
*** 3479,3484 **** PostgresMain(int argc, char *argv[], const char *username)
--- 3479,3494 ----
  	}
  
  	/*
+ 	 * Load shared preload libraries on single-user mode.
+ 	 * Because this routine is not invoked from PostmasterMain() that
+ 	 * loads shared preload libraries prior to fork the backend process,
+ 	 * the 'shared_preload_libraries' shall be implicitly ignored.
+ 	 * So, we need to load them on single-user mode.
+ 	 */
+ 	if (!IsUnderPostmaster)
+ 		process_shared_preload_libraries();
+ 
+ 	/*
  	 * You might expect to see a setsid() call here, but it's not needed,
  	 * because if we are under a postmaster then BackendInitialize() did it.
  	 */