## 37.7. Limitations and Missing Features

The following features are currently missing from PL/Perl, but they would make welcome contributions.

- PL/Perl functions cannot call each other directly (because they are anonymous subroutines inside Perl).

- SPI is not yet fully implemented.

- In the current implementation, if you are fetching or returning very large data sets, you should be aware that these will all go into memory. Future features will help with this. In the meantime, we suggest that you not use PL/Perl if you will fetch or return very large result sets.