Suppose you have this query

 

 

SELECT Pname, Price, Color

FROM PRODUCT

WHERE Price < 50 OR Color = ‘Red’;

 

 

 

• Which technique can be used to improve this query ?

 

Q2.With a neat state transition diagram explain the states for transaction execution.

Q3. Consider the four transactions T1, T2, T3, T4 and the schedules S given below.

 

 T1: w1(A); w1(B) 

T2: r2(A); r2(C); w2(D) 

T3: r3(B); w3(E) 

T4: r4(D), w4(E) 

S: w1(A), r2(A), w1(B), r2(C), r3(B), w2(D), w3(E), r4(D), w4(E)

 

A. Draw the serializibility (precedence) graph for S 

B. If S is serializible, write down the equivalent serial schedule(s). 

 

 

Q4.What are Essential components in Two-Phase Locking Techniques? draw conflict matrix