Aqui
https://public.commandprompt.com/documents/5 dice esto
Limitations
PL/php functions cannot call each other directly because their names are mangled.
SPI calls have the whole results allocated in memory, so processing huge results may be problematic. Also it's not possible to use cursors with SPI.
Ustedes creen que signifique que utilice mas memoria ram, que pl/pgsql?