Fast Path

• Postgres provides a fast path interface to send function calls to the backend. This is a trapdoor into system internals and can be a potential security hole. Most users will not need this feature.

  PGresult* PQfn(PGconn* conn,
                 int fnid,
                 int *result_buf,
                 int *result_len,
                 int result_is_int,
                 PQArgBlock *args,
                 int nargs);
  

  The fnid argument is the object identifier of the function to be executed. result_buf is the buffer in which to load the return value. The caller must have allocated sufficient space to store the return value. The result length will be returned in the storage pointed to by result_len. If the result is to be an integer value, than result_is_int should be set to 1; otherwise it should be set to 0. args and nargs specify the arguments to the function.

  typedef struct {
               int len;
               int isint;
               union {
                   int *ptr;
                int integer;
               } u;
           } PQArgBlock;
  

  PQfn always returns a valid PGresult*. The resultStatus should be checked before the result is used. The caller is responsible for freeing the PGresult with PQclear when it is not longer needed.