Question
Hello, I would like to solve these questions today as text, please Question 1 Consider a bank database with this partial schema: Branch(bNo, bAddress, Bphone)
Hello, I would like to solve these questions today as text, please
Question 1
Consider a bank database with this partial schema: Branch(bNo, bAddress, Bphone) Customer(cID, name, phone, cAddress) Account(aNo, type, balance, bNo)
Customers Accounts(cID, aNo)
Apply the equivalence rules to generate an optimized final tree of this query: SELECT C.name, C.phone, A.aNo, A.balance
FROM Branch B, Customers Accounts CA, Account A, Customer C
WHERE A.balance > 10,000 AND B. bAddress = "Riyadh" AND C. phone > B.Bphone AND C.cAddress=B. bAddress AND B.bNo=A.bNo AND CA.aNo=A.aNo AND CA.cID=C.cID;
Note: the joins costs are CA on A = 100; 000 records, A on B = 150; 000 and C on CA = 95; 000 records.
Question 2
Consider the following schedule S, consisting of transactions T1, T2 and T3
T1 | T2 | T3 |
begin |
|
|
| begin |
|
|
| begin |
|
| Write(A) |
Read(A) |
|
|
| Write(B) |
|
|
| Write(B) |
| Write(B) |
|
|
| commit |
Write(A) |
|
|
| Read(B) |
|
Read(B) |
|
|
commit |
|
|
| commit |
|
- Draw the precedence graph of transactions to determine whether the schedule is conflict-serializable.
- For the same schedule determine if they are view serializable. If found be view serializable, give a corresponding serial schedule, if not view serializable provide a suitable justification.
Question 3
For the following schedule, determine the following:
- Has a deadlock occurred in the schedule? Show the WFG.
- Which transaction(s), if any, would abort using Wait-Die technique and when?
- Which transaction(s), if any, would abort using Wound-Wait technique and when?
| T1 | T2 |
t1 | begin |
|
t2 |
| begin |
t3 |
| Lock-s(y) |
t4 |
| Read(y) |
t5 | Lock-X(x) |
|
t6 | Read(x) |
|
t7 | Write(x) |
|
t8 |
| Lock-S(x) |
t9 |
| Read(x) |
t10 | Lock-X(y) |
|
t11 | Read(y) |
|
t12 | Write(y) |
|
t13 |
| Commit/unlock (y,x) |
t14 | Commit/unlock (x,y) |
|
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