Q Table View + Relational Model VERY SLOW

ok guys a BIG question...

I ve loaded a mysql table using a relational table model in a qtableview...
Table contains about 50 columns of which 18 are foreign keys to other tables.... and 150 records..
i.e. i used the setRelation() method 18 times or so...


the table loads and shows OK... but VERY VERY slow.... 1 minute...
If I press a column to sort that takes another 1 minute to refresh or so...
using QT with C++, running linux,on a dualcore 2.33 GHz pc..
this does not add up...right? dont tell me there is not a bottleneck somewhere......

is it the MySql server?
IDEAS on how to speed things up??

thanks ! :confused:

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Added after 8 minutes:

ok it appears that if I reduce the number of times i call model->setRelations() from 18 to 15 the performance goes sky high... from 1 minute down to 4 seconds.....!!!

ok I know that there is a constraint in MySQL where you can have up to 15 (or 16) indexed columns in a single index in each table....

anything above that and mysql will not accept it...

any ideas on that?
possibly a bug?