Feature request: if possible, support variable column definitions? about sqlite-vtfunc HOT 1 CLOSED

I don't believe this is do-able. Read the SQLite virtual tables API doc for background. What vtfunc does is it takes your TableFunction and tells sqlite (via sqlite3_create_module) that the table function provides a virtual table and implements x, y, z methods. vtfunc makes an additional caveat in the way it declares its callbacks that it is an eponymous-only virtual table (e.g., you cannot create virtual table ... with the tablefunction module). When sqlite sees us querying our virtual table directly, it calls the xConnect callback we registered. At this point we have no information about the query, the parameters, the row values...nothing...and we need to tell sqlite the structure of our table (sqlite3_declare_vtab). If you look in the code for pwConnect you'll see that there's no TableFunction instance in there -- because we don't have enough information yet to create one. That happens later in the xOpen callback.

from sqlite-vtfunc.