ANSWER If two concurrent transactions access a data item that is being updated by one of them, it is not possible to guarantee that the second will read the correct value. Dirty reads and nonrepeatable reads may occur when one transaction can see intermediate results of another transaction before it as been committed. Given below are two concurrent transactions (bal,) were recorded at times between t, and tg As shown in the table below: If these two transactions interfere with each other, fill in the table below by selecting from the drop down list the values of balance X ( bal,) at specified times between ty and to- Time T1 T 52 " 44 Begin, Transaction Read(bal) bal-bal-10 Write(bal) Commit 12 Begin, Transaction Readibal bal, bal,+100 Write(bal) rollback bal, 100 100 and T2 whose balances of amountx

The recurring transaction type that generates an alert when we should use a recurring transaction to enter a new transaction is

Consider a schedule with 4 transactions with 1, 2, 3, and 4 operations respectively. Calculate the possible number ofa) Serial schedulesb) Non serial schedules Please answer these question in detail with full explaination. I need a proper long answer. Thanks :)

The Oracle database system uses undo log records to provide a snapshot view of the database under snapshot isolation. The snapshot view seen by transaction Ti reflects updates of all transactions that had committed when Ti started and the updates of Ti; updates of all other transactions are not visible to Ti. Describe a scheme for buffer handling whereby transactions are given a snapshot view of pages in the buffer. Include details of how to use the log to generate the snapshot view. You can assume that operations as well as their undo actions affect only one page.

The following two transactions result in a deadlock. Show through examples how this deadlock can be dealt with or avoided using conservative and basic two-phase locking algorithms. T'1 read_lock (Y); read_item (Y); write_lock (X); (waits for X) T'2 read_lock (X); read_item (X); write_lock (Y); (waits for Y)

Consider the schedule below. Here, R(*) and W(*) stand for 'Read' and 'Write', respectively. T1, T2, T3, T4 and T5 represent five transactions and ti represents a time slot. ti t2 t3 t4 t5 t6 t7 t8 t9 ti0 t11 t12 t13 t14 t15 t16 t17 t18 T1 R(A) R(B) W(A) W(B) T2 R(C) W(C) T3 R(B) R(C) W(B) W(C) T4 R(D) W(D) R(A) W(A) T5 R(C) R(A) W(C) W(A) Each transaction begins at the time slot of its first Read and commits right after its last Write (same time slot). Regarding the following questions, give and justify your answers. 3) Construct a schedule (which is different from above) of these five transactions which causes deadlock when using two-phase locking protocol. You should clearly indicate all the locks and the corresponding unlocks in your schedule. If no such schedule exists, explain why. 4) Construct a schedule (which is different from above) of these five transactions which does not cause deadlock when using two-phase locking protocol. You should clearly indicate all the locks and the…

Transactions often take a very long time to finish when an optimistic approach to concurrency management is used. Explain.

When an optimistic approach to concurrency management is used, transactions often take a very lengthy time to complete. Explain.

Consider the database containing transaction data as shown in the table below. Apply Apriori algorithm and find the frequent itemsets where min-sup=2.   TID Items Bought 1 Daiper, Bread, Juice 2 Eggs, Bread, Pasta 3 Daiper, Eggs, Bread, Pasta 4 Eggs, Pasta 5 Rice

All transactions have four properties: Atomicity, Consistency, Isolation, and Durability. These four properties are also known as the ACID test of transactions. In addition, multiple transactions must conform to the property of serializability. Concurrency controlling techniques ensure that multiple transactions are executed simultaneously while maintaining the ACID properties of the transactions and serializability in the schedules. Explain the following statement: a transaction is a logical unit of work.What are some disadvantages of time-stamping methods for concurrency control?Why might it take a long time to complete transactions when an optimistic approach to concurrency control is used?