rows.Scan() optimal usage

gistfile1.go

//Prepare buffers for reading: one time before read first chunk

treader.rawBuffer = make([]sql.RawBytes, len(treader.columns))
// rows.Scan wants '[]interface{}' as an argument, so we must copy the
// references into such a slice
// See http://code.google.com/p/go-wiki/wiki/InterfaceSlice for details
treader.scanCallArgs = make([]interface{}, len(treader.rawBuffer))
for i := range treader.rawBuffer {
	treader.scanCallArgs[i] = &treader.rawBuffer[i]
}

//Read one chunk of data

csvRows := make([][]string, 0, chunkSize)
lastRowID := 0
for rows.Next() {
	err := rows.Scan(treader.scanCallArgs...)
	if err != nil {
		panic(fmt.Errorf(string("Can not parse query result %s "), err.Error()))
	}

	csvCurrentRow := make([]string, 0, len(treader.scanCallArgs))
	for i, col := range treader.rawBuffer {
		if i == treader.primaryKeyIndex {
			strCol := string(col)
			if _, ok := treader.blacklistedColumns[i]; !ok {
				csvCurrentRow = append(csvCurrentRow, strCol)
			}

			if pk, err := strconv.Atoi(strCol); err != nil {
				panic(fmt.Errorf(string("Primary key must be int: %s"), strCol))
			} else {
				lastRowID = pk
			}
		} else if _, ok := treader.blacklistedColumns[i]; ok {
			//column is blacklisted
			continue
		} else if col == nil {
			csvCurrentRow = append(csvCurrentRow, "")
		} else {
			csvCurrentRow = append(csvCurrentRow, string(col))
		}
	}

	csvCurrentRow = treader.fileInfo.mapper(csvCurrentRow, treader.fieldMap)
	csvRows = append(csvRows, csvCurrentRow)
}