Define these terms: transaction, atomicity, consistency, isolation, durability, schedule, dirty read, and serializable schedule.
Describe Strict 2PL.
Consider the following actions taken by transaction T1 on database objects X and Y: R(X), W(X), R(Y), W(Y).
a. Give an example of another transaction T2 that, if run concurrently to transaction T without some form of concurrency control, could interfere with T 1.
b. Explain how the use of Strict 2PL would prevent interference between the two transactions.
c. Strict 2PL is used in many database systems. Give two reasons for its popularity.
The database management systems can be classified based on several criteria.
A. Based on data model: the relational data model; hierarchical data model; network data model; or object-oriented data models.
B. Based on the number of users: single user database system which supports one user at a time or multiuser systems which support multiple users concurrently.
C. Based on the ways database is distributed: Centralized Systems (the system is stored at a single site.); Distributed database system (Actual database and DBMS software are distributed in various sites connected by a computer network.) - Homogeneous distributed Database Systems or Heterogeneous distributed Database Systems. Choose three different types of the database management systems. Do your research on these DBMS, explain and discuss about these different systems. (the main features, applications, comparisons of advantages or disadvantages.) Please cite the references (books, website, etc...)
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1. The definitions given below are generally obtained by paraphrasing the definitions provided in the textbook.
A transaction is a sequence of operations (between “begin transaction” and “end transaction”) executed by a unit of a program for performing access and update to/of data items. The component operations are hidden to user and they appear as a single execution unit.
Atomicity represents the insurance that execution of a transaction is complete and the targeted effects are visible into the database. It means there are not left incomplete states for the transaction....
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