QSqlquery size returns -1 when forwardOnly is enabled

[Kiruahxh]

Hi,
With a postgres database on linux with QPSQL driver, I cannot retrieve the number of results of a query with "size()" method, it always returns -1.
Ex:

bool hasSupport = QSqlDatabase::database().driver()->hasFeature(QSqlDriver::QuerySize);
QSqlQuery query;
query.setForwardOnly(true); // this prevents from getting nbRows
query.exec("select 123");
int nbRows = query.size();
query.first();
int val = query.value(0).toInt();

"hasSupport => true"
"nbRows => -1"
"val => 123"

I guess that when using QPSQL driver, setForwardOnly() is incompatible with size()?
I didn't see it documented anywhere

[Christian Ehrlicher]

ForwardOnly queries can't return the complete query size.