Consider the following two transactions: T1 R(A), W(A), R(B), RIC) T2- W(C), R(B), R(A). W(B) Say that sharing lock, exclusive lock, and unlock actions are inserted by the scheduler, resulting in the following annotated transactions T1- X(A), R(A), W(A), S(B), R(B), S(C), U(A), R(C), U(B), S{C) T2- X(C), W(C), X(B), S(A), U(C), R(B), R(A), U(A), W(B), U(B) The above schedule follows 2 PL so conflict serializability is guaranteed. True False

Consider the following two transactions: T1 R(A), W(A), R(B), RIC) T2- W(C), R(B), R(A). W(B) Say that sharing lock, exclusive lock, and unlock actions are inserted by the scheduler, resulting in the following annotated transactions T1- X(A), R(A), W(A), S(B), R(B), S(C), U(A), R(C), U(B), S{C) T2- X(C), W(C), X(B), S(A), U(C), R(B), R(A), U(A), W(B), U(B) The above schedule follows 2 PL so conflict serializability is guaranteed. True False

Database System Concepts

7th Edition

ISBN:9780078022159

Author:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Publisher:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Chapter1: Introduction

Section: Chapter Questions

Problem 1PE

See similar textbooks

Similar questions

????????????/
v) Choose all the functional dependencies that holds in the following table a. A>B b. B>C A B |C f e f i c. B>A d. A→C e i e. C→B g h k
We have the following two transactions:T1: R(A), R(B), if A = 0 then B:=B+1, W(B)T2: R(B), R(A), if B = 0 then A:=A+1, W(A)Basis consistency is guaranteed by A = 0 ∨ B = 0 with initial values A = B = 0.a) Show that after both possible successive executions the database maintains consistency.b) Give an example where concurrent execution would lead to database inconsistencyc) Is there an example of concurrency that would preserve consistency?
Consider the following transaction database: tid 1₁ 12 13 14 15 16 17 18 itemset ABCD ACDF ACDEG ABDF BCG DFG ABG CDFG a) Using minsup = 3/8, show how the Apriori algorithm enumerates all frequent itemsets. b) Using minconf=0.80, generate all association rules from above frequent 3-itemsets.
{T1,T2,T3} -> Transactions {A,B,C,D,E,F,G} -> Database objects L(x) -> X locking X object. U(x) -> Unlocking X object. R -> Read & W -> Write Can we transform below transaction schedule to serial action plan ? Show with Presedence Graph method. If yes what are the equal serial plans ? (as lock mechanism use Strict-2PL)
(b) Consider the following schedule of two transactions: R(B) в€ 100 - В W(B) R(A) R(A) R(B) A € 10A + B в € 2B + A A € 30 + 7B W(A) W(A) W(B) Figure 3: Schedule of Q5(b). i. Result-serializability is when the result of a schedule is the same as some serial 10 and B = 20, show if this schedule is schedule. Given the initial values A result-serializable or not. ii. Show how to add locks/unlocks to make the two transactions T1 and T2 conflict serializable.
Please answer this question. Thank you!
Given the following transaction dataset: Tid Items 10 A, C, D 20 B, C, D 30 A, B, C, D 40 B, D 50 A, C, D And a minimum support of 3 (minsup = 3) What are all the frequent itemsets? What are all the rules from these frequent itemsets?
We have the following transactions with associated schedulesT1: R(A) R(B) W(A)T2: R(A) R(B) W(A) W(B)a) Give the schedule of transactions T1 and T2 that leads to a WR conflict.b) Give the schedule of transactions T1 and T2 that lead to RW conflict.c) Give the schedule of transactions T1 and T2 that leads to a WW conflict.d) For each of the given schedules, show how a strict 2FZ would prevent this.
Consider a relation R(a, b, c, d) containing 1 million records, where each page of the relation holds 10 records. R is organized as a heap file with unclustered indexes, and the records in R are randomly ordered. Assume that attribute a is a candidate key for R, with values lying in the range 0 to 999,999. For each of the following queries, name the approach that would most likely require the fewest I/Os for processing the query. The approaches to consider follow: ■ Scanning through the whole heap file for R. Using a B+ tree index on attribute R.a. Using a hash index on attribute R.a. The queries are: 1. Find all R tuples. 2. Find all R tuples such that a 50 and a < 100.
Question 2 1. Given R (A, B, C, D, E, F) and the following set of functional dependencies: F = {A→EDC, B→D, E→CF, ED→A, EB→C} a. Show that AB is a primary key of R. b. Explain why R is not in the 2NF? c. Give a decomposition of R that is in 2NF. d. Explain why R is not in 3NF? Give a decomposition of R that is in the 3NF. е.
Consider two relations R and S of size 1200 bytes and 1000 bytes respectively. The size of a tuple in both relations is 20 bytes. The block size of the system is 100 Bytes. How many extra block transfers would be required, in the worst case, if nested loop join is used instead of block nested loop join technique to compute the natural join?