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Scanning (cont)

In this case, the implementation changes to: 

for each page P in data file of relation Rel {
    for each tuple t in page P {
        add tuple t to result set
    }
    for each overflow page V of page P {
        for each tuple t in page V {
            add tuple t to result set
}   }   }

Cost: read each data page and each overflow page once

Cost = b + bOv

where bOv = total number of overflow pages