It's extremely important,I need its answer as fast as you can please.

II . Answer or compute the question

1. Explain the concept of ' Transaction ' and its ACID properties .

2. Given two relation schemas P ( A , B , C , D ) and Q ( C , E , F , G ) , there are two . equivalent algebra expressions El and E2 . Try to analysis and discuss which has better performance EIIA ( OB - EAG - 90 ( PQ ) ) E2A ( OB - E ( P ( OG - 99 ( Q ) ) ) =

3. What is 2 - phase lock protocol , try to discuss its usage and disadvantages .

4. What is the notion of conflict equivalent ? Is the following schedule conflict . serializable ? If it is , please transfer it into a serial schedule . E.g. TW ( y ) indicates Transaction T3 write data item y . Original schedule : T , W ( y ) , T , R ( x ) , T , R ( y ) , T , W ( x ) , TW ( x ) , T , W ( z ) , T.R ( z ) , T , W ( x ) Note : Please write down the swapping steps . =

II. Answer or compute the question(total 36 points) 1. (6 points)Explain the concept of 'Transaction' and its ACID properties. 2. (4 points) Given two relation schemas P(A,B,C,D) and Q(C,E,F,G), there are two equivalent algebra expressions E1 and E2. Try to analysis and discuss which has better performance . E1=A(B=EG=99(PQ))E2=A(B=E(P(G=99(Q))) 3.(6 points)What is 2-phase lock protocol, try to discuss its usage and disadvantages. 4.(6 points) What is the notion of conflict equivalent? Is the following schedule conflict serializable? If it is, please transfer it into a serial schedule. E.g. T3W(y) indicates Transaction T3 write data item y. Original schedule: T3W(y),T1R(x),T2R(y),T3W(x),T2W(x),T3W(z),T4R(z),T4W(x) Note: Please write down the swapping steps