Patrick Handja <patrick.bungama@gmail.com> writes: > I would like to know if there is a better way to pass a relation or if the > relation name (CString) as a parameter in a C function and thus be able to > manipulate its tuples. The documentation is available here: > https://www.postgresql.org/docs/13/xfunc-c.html#id-1.8.3.13.11. But it is > not quite clear enough on how to retrieve tuples.
The thing I'd recommend you do is use SPI [1], which lets you execute SQL queries from inside a C function. If you don't want to do that for whatever reason, you need to open the relation, set up a scan, and fetch tuples from the scan, relying on low-level APIs that tend to change from version to version. contrib/pageinspect or contrib/pgstattuple might offer usable sample code, although with any prototype you might look at, it's going to be hard to see the forest for the trees.
