Data Access Physical blocks are those blocks residing on the disk. Buffer blocks are the blocks residing temporarily in main memory. ■ Block movements between disk and main memory are initiated through the following two operations: input(B)transfers the physical block B to main memory. output(B)transfers the buffer block B to the disk,and replaces the appropriate physical block there. We assume,for simplicity,that each data item fits in,and is stored inside, a single block. Database System Concepts-7th Edition 19.8 ©Silberscha乜，Korth and SudarshanDatabase System Concepts - 7 19.8 ©Silberschatz, Korth and Sudarshan th Edition Data Access ▪ Physical blocks are those blocks residing on the disk. ▪ Buffer blocks are the blocks residing temporarily in main memory. ▪ Block movements between disk and main memory are initiated through the following two operations: • input (B) transfers the physical block B to main memory. • output (B) transfers the buffer block B to the disk, and replaces the appropriate physical block there. ▪ We assume, for simplicity, that each data item fits in, and is stored inside, a single block