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Justify The Following Statement: Concurrent Execution Of Transactions Is More Important When Data Must Be Fetched From (slow) Disk Or When Transactions Are Long, And Is Less Important When Data Is In Memory And Transactions Are Very Short. |
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Answer» If a transaction is very long or when it fetches data from a slow disk, it takes a long TIME to COMPLETE. In absence of CONCURRENCY, other transactions will have to wait for longer period of time. Average response time will increase. Also when the transaction is reading data from disk, CPU is idle. So resources are not properly utilized. Hence concurrent execution becomes important in this case. However, when the transactions are short or the data is available in memory, these problems do not OCCUR. If a transaction is very long or when it fetches data from a slow disk, it takes a long time to complete. In absence of concurrency, other transactions will have to wait for longer period of time. Average response time will increase. Also when the transaction is reading data from disk, CPU is idle. So resources are not properly utilized. Hence concurrent execution becomes important in this case. However, when the transactions are short or the data is available in memory, these problems do not occur. |
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