Consider the following protocol for concurrency control. The database system assigns each transaction a unique and...
Fantastic news! We've Found the answer you've been seeking!
Question:
Transcribed Image Text:
Consider the following protocol for concurrency control. The database system assigns each transaction a unique and strictly increasingly id at the start of the transaction. For each data item, the database system also keeps the id of the last transaction that has modified the data item, called the transaction-id of the data item. Before a transaction T wants to read or write on a data item A, the database system checks whether the transaction-id of A is greater than the id of T. If this is the case, the database system allows T to read/write A. Otherwise, the database system aborts and restarts T. (a) Does this protocol allows only serializable schedule for transactions? If not, you may suggest a change to the protocol so that all schedules permitted by this protocol are serializable. You should justify your answer. (b) Propose a change to this protocol or the modified version you have designed for part (a) that increases its degree of concurrency, i.e., it allows more serializable schedules. Consider the following protocol for concurrency control. The database system assigns each transaction a unique and strictly increasingly id at the start of the transaction. For each data item, the database system also keeps the id of the last transaction that has modified the data item, called the transaction-id of the data item. Before a transaction T wants to read or write on a data item A, the database system checks whether the transaction-id of A is greater than the id of T. If this is the case, the database system allows T to read/write A. Otherwise, the database system aborts and restarts T. (a) Does this protocol allows only serializable schedule for transactions? If not, you may suggest a change to the protocol so that all schedules permitted by this protocol are serializable. You should justify your answer. (b) Propose a change to this protocol or the modified version you have designed for part (a) that increases its degree of concurrency, i.e., it allows more serializable schedules.
Expert Answer:
Answer rating: 100% (QA)
a No this protocol does not necessarily allow only serializable schedules for transactions This can ... View the full answer
Related Book For
Concepts of Database Management
ISBN: 978-1285427102
8th edition
Authors: Philip J. Pratt, Mary Z. Last
Posted Date:
Students also viewed these operating system questions
-
QUIZ... Let D be a poset and let f : D D be a monotone function. (i) Give the definition of the least pre-fixed point, fix (f), of f. Show that fix (f) is a fixed point of f. [5 marks] (ii) Show that...
-
can someone solve this Modern workstations typically have memory systems that incorporate two or three levels of caching. Explain why they are designed like this. [4 marks] In order to investigate...
-
The milk plant in a city distributes its products by trucks, loaded at a single loading dock. It has its own fleet plus trucks of a private company. The private company has complained that sometimes...
-
What techniques do writers of successful online sales messages use?
-
Calculate the molar solubility of strontium sulfate, SrSO4, in 0.0015 M sodium sulfate, Na2SO4. Solve the equation exactly. See Table 17.1 for Ksp. TABLE 17.1 Solubility Product Constants, Ksp at 25C...
-
Follow up the derivations leading to the Blasius equation leading to \[f^{\prime \prime \prime}+f f^{\prime \prime}=0\] A useful routine to solve this is BVP4C in MATLAB. Solve the Blasius equation...
-
Tisdale Incorporated reports the following amount in its December 31, 2015, income statement. Required: 1. Prepare a multiple-step income statement. 2. Explain how analyzing the multiple levels of...
-
A company using the perpetual inventory system purchased inventory worth $12.000 on account with credit terms of 1/15, 30 Detective inventory was received, but instead of a return, an allowance of...
-
Illustrate how fine-line inventory classification can be used with product and market segments. What are the benefits and considerations when classifying inventory by product, market, and...
-
2. Although only one level of measurement typically is associated with a given variable, it is frequently possible to measure a variable at more than one level. For example, while the variable "age"...
-
The phase margin (in degrees) of a system having the loop transfer function \(\mathrm{G}(s) \mathrm{H}(s)=\frac{2 \sqrt{3}}{s(s+1)}\) is (a) 45 (b) -30 (c) 60 (d) 30
-
You may already be familiar with Just Eat, which is an app that allows you to find and choose from a whole range of food outlets near your location. What you may not know is that this was created in...
-
South Charleroi Airport is a regional airport serving the leisure travel market. The inverse demand curve for this airport is P = 150 Q. Assume that there are only two airlines serving this airport,...
-
Suppose that \(x_{i}\) is endogenous in the regression \(y_{i}=\beta_{1}+\beta_{2} x_{i}+e_{i}\). Suppose that \(z_{i}\) is an instrumental variable that takes two values, one and zero with...
-
Demosthenes, the great Greek orator of antiquity, is supposed to have claimed that the most important canon was delivery, the second most important was delivery, and the third most important was...
-
Jazz company started construction on a building on January 1 of this year and completed construction on December 31 of the same year. Jazz had only two interest notes outstanding during the year, and...
-
d. The characteristic equation of a control system is given by s+2s+8s+12s+20s+16+16=0. Determine the number of the roots of the equation which lie on the imaginary axis of s-plane
-
Suppose in addition to the requirements specified in Question 7, you must store the number of the department in which the student is majoring. Indicate the changes this would cause in the design in...
-
Using your knowledge of the college environment, identify three transactions that might be handled by online transaction processing (OLTP) systems.
-
In the following exercises, you will use the data in the TAL Distributors database shown in Figure 2-1 in Chapter 2. (If you use a computer to complete these exercises, use a copy of the original TAL...
-
Which of the following function(s) is/are carried out by piRITS or piRISC? a. Inhibits transcription of TEs b. Causes the degradation of TE RNA c. Causes chromosome breakage d. Both a and b are...
-
Scientists propose that the first macromolecules in protobionts were a. DNA molecules. b. RNA molecules. c. proteins. d. all of the above.
-
In the CRISPR-Cas system, what does tracrRNA bind to? a. crRNA and Cas1 protein b. crRNA and Cas2 protein c. crRNA and Cas9 protein d. Cas1 and Cas2 proteins
Study smarter with the SolutionInn App