Hi all, I'm trying to understand the example of user defined functions in MonetDB (https://www.monetdb.org/Documentation/Cookbooks/SQLrecipes/UserDefinedFunct ion). I understand the concept for just reversing a string. But what about working with tabular data? I'd like to pass to this C function a whole table (list of rows) and then return another table(s)/write result data to other tables. What is the correct way of doing this? Can I pass some kind of arrays to the C function? Can I return these arrays from a function? Or is it possible to query the DB directly from the C script? Thank you very much for some answers. Best regards, Jiri Nadvornik Astronomical Institute AV CR Stellar department Czech Republic <mailto:nadvornik.ji@gmail.com> nadvornik.ji@gmail.com