query Q_2(dorewrite = false, runquery = true) {    
    double memoryInGB = runtime.totalMemory / 1073741824.0;    
        
    long windowSize = 10;    
    if (memoryInGB < 1) 
        windowSize = 5;    
                            
    ElementWindow windowOp{size = windowSize};
    
    Aggregate aggregateOp{
        aggregations = [["AVG", bid.PRICE, "AVG_PRICE"]],
        group_by = [bid.AUCTION]};
    
    Operator[] sinks();    
    for (int i = 1; i<=5; i++) {
        sinks += new ODLSelect{predicate = "bid.AUCTION = "+i};
    }        
        
    bid -> windowOp -> aggregateOp -> sinks;
}