Whenever a query is executed without the db_return method and it is a
select query, then it is counted and if it is over a max value it will
return false and terminate.
With those functions that counter value can be checked and reset.
To be used carefully. It is recommended to rather make often called
queries with the same values prepare/execute style instead of resetting
the count.
Some tables do not have primary keys, so an override code is needed to
avoid getting auto returning set there.
If db exec is called 'NULL' (or the async version), then no RETURNING is
added or checked.
schema to the current one
* check current schema and set prefix to table if needed
* check that if cursor is null we do not try to get any data but return false
