Performance of Using QSqlTableModel

[silentyears]

What is "doSomething()" doing ?

let's say as follows,

void doSomething()
{
   i++;
}

void doSomething()
{
   i++;
}

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so this mean that the "while" loop need too much time to execute itself. Now i notice that tableA has a field which store blob, once i don't select this field, then the speed become fast! Why and how to deal with blob with QSqlTableModel?
thanks!