Questions and Answers of Principles Of Database Management

When can the relative location technique for record organization be problematic?a. When there are many missing values in records.b. When there is a large number of records.c. When there are many
How can we improve the speed of physically retrieving a record based on a search key?
In which of these cases can we make use of delimiters to separate attributes?a. The data are stored in mixed files.b. Some attributes have data types that can have variable lengths as
What is the difference between a bucket address, a relative block address, and an absolute block address when talking about key-to-address transformation (a hashing algorithm)?
Why is the blocking factor important to know?a. For calculating the seek time of a hard disk drive.b. For achieving efficient access to records.c. For determining the maximum size of the
Discuss the advantages and disadvantages of secondary indexes. When would it be useful to maintain a secondary index?
Which of the following statements with regards to search keys is not correct?a. A search key can be composite, meaning that it can consist of a combination of values.b. A search key needs to be a
Discuss the differences between and (dis)advantages of heap files, sequential files, and random file organization.
Which of the following statements with regards to search trees, B-trees, and B+-trees is correct?a. An unbalanced B-tree allows for additional performance gain by reducing the height of the
Which of the following statements is not correct?a. Index creation can help improve the performance of join queries.b. Indexing makes it harder to enforce uniqueness on a (combination of)
Illustrate how SQL can be used to create an index called CUSTOMER_INDEX, on the table with name CUSTOMERS based on the CUSTOMER_AGE (descending) and CUSTOMER_ZIPCODE (ascending) attribute types. Give
Suppose you work for a bank and have to create a contingency plan. Compare your RTO and RPO objectives with other businesses and organizations.What kind of RAID set-up would you choose? What kind of
Which statement is not correct?a. RAID level 0 is used if performance is more important than fault tolerance.b. To store the same amount of data, RAID 1 needs twice the amount of storage capacity
Which statement is not correct?a. The management of data storage is more expensive than the purchase of storage hardware, which is why businesses opt for enterprise storage subsystems.b. “Network
Which statement is not correct?a. A transaction is a set of database operations (e.g., a consecution of SQL statements in a relational database), induced by a single user or application, that should
What DBMS components are typically involved in transaction management?
Discuss the lost update, uncommitted dependency, and inconsistent analysis problem. Illustrate with an example. Which ones result in an inconsistent database state?
One newer and promising NoSQL database is VoltDB, as it tries to combine the best aspects of RDBMSs and the NoSQL movement. Its documentation states the following:As a fully ACID, distributed SQL
Apart from using a map–reduce pipeline to write complex queries in MongoDB, it also provides an “aggregate” command through which you can define an aggregation pipeline consisting of several
When are column-oriented databases more efficient?a. When many columns of a single group need to be fetched at the same time.b. When inserts are performed where all of the row data are supplied at
A fun programming exercise is to implement a basic gossip membership protocol. You can even simulate this locally in one program, so you don’t have to run it over a network of computers. Remember
Which of the following statements is not correct?a. Graphs are mathematical structures consisting of nodes and edges.b. Graph models are not capable of modeling many-to-many relationships.c. Edges
What does the following Cypher query express?a. Get the node for Bart Baesens and a count of all his friends, but only if at least one FRIENDS_WITH relation exists.b. Get the node for Bart Baesens
Using Cypher, how do you get a list of all movies Wilfried Lemahieu has liked, when he has given at least four stars? a. b. C. d. SELECT (b:User)--(m:Movie) WHERE b.name = "Wilfried Lemahieu" AND
Which statement is not correct?a. A primary element of a contingency plan is the quantification of recovery objectives in RTO and RPO, given the organization’s strategic priorities.b. The only
Statement 1: When opting for hard drive backups to maintain data availability in case of a calamity, the RPO depends on the underlying infrastructure. Choosing a SAN as a storage subsystem might be a
Which of the following file organization methods is not a primary file organization method?a. Linked lists.b. Sequential file organization.c. Heap files.d. Hash file organization.
Which of the following statements with regards to random file organization is correct?a. In order to avoid overflow, the hashing algorithm that distributes keys to bucket addresses needs to be
Which of the following statements with regards to indexed sequential file organization is correct?a. The search key of a sparse index is a unique key (i.e., a primary key or candidate
Which of the following statements is correct?a. Secondary file organization methods make insertion and deletion of records a lot easier.b. An important application of tree data structures is when
Which of the following statements is correct?a. Current versions of SQL require a specific internal data model.b. Current versions of SQL impose a specific physical implementation of internal data
What is intra-query parallelism? How does the concept of a tablespace enable it?
Which of the following statements is not correct?a. The more selective a query predicate’s FF, the less desirable it is to use the index on the corresponding attribute type in the access
Given two tables R and S, which of the following join strategies is described by the following algorithm:a. Hash join.b. Sort-merge join.c. Nested-loop join.d. None of the above. Denote S outer
Discuss and compare three different techniques to physically implement a join.
Given two tables R and S, which of the following join strategies is described by the following algorithm:a. Hash join.b. Sort-merge join.c. Nested-loop join.d. None of the above. Stage 1: sort R
Which three techniques are used in a RAID set-up? Which configuration of options of each of these three techniques is best used for very critical data, in terms of business continuity?
Along which three criteria can storage subsystems be classified? Situate the DAS, SAN, NAS, NAS gateway, and iSCSI approaches along each of these three criteria.
Which of the following statements is correct?a. SQL is a declarative language, meaning that the programmer has to specify which data to retrieve and how the data are to be located and retrieved from
Which statement is not correct?a. It is often more efficient to combine multiple smaller physical disk drives into one larger logical drive because having multiple physical drives allows for
Which statement is not correct?a. A DAS does not offer out-of-the-box capabilities for centralized storage management and sharing unused disk capacity across servers.b. A SAN is typically best in
When a transaction is aborted, it is important that…a. All changes made by the individual operations belonging to that transaction should be made permanent.b. A rollback of the transaction is
Which of the following DBMS components is involved in transaction management?a. Scheduler.b. Stored data manager.c. Buffer manager.d. Recovery manager.e. All of the above.
What is the difference between a serial and serializable schedule and why is this difference important? How can a schedule be tested for serializability?
The following figure presents five transactions (T1 until T5) that are executed more or less simultaneously. Suppose a checkpoint was registered on the logfile at time tc, marking the last time when
Which statement is not correct?a. The logfile contains all updates after they have been written to disk.b. The logfile contains redundant data.c. The logfile can be implemented as a sequential
Work out the compatibility matrix illustrating which requests can be granted given the locks (shared or exclusive) currently held on a database object.
Which statement is not correct?a. Disk mirroring is a (near) real-time approach that writes the same data simultaneously to two or more physical disks.b. Archiving is an approach in which database
Discuss the Two-Phase Locking Protocol and the different variants thereof. Illustrate how this protocol can help address the lost update, uncommitted dependency, and inconsistent analysis problems.
Which statement is not correct?a. A lost update problem occurs if an otherwise successful update of a data item by a transaction is overwritten by another transaction that wasn’t “aware” of
Complete the following table by indicating which concurrency problems can occur based on the isolation level. Isolation level Read uncommitted Read committed Repeatable read Serializable Lost
What is a deadlock? Illustrate with an example.
If the precedence graph contains a cycle, the schedule is…a. Serializable.b. Not serializable.
Which statement is not correct?a. An optimistic protocol assumes that conflicts between simultaneous transactions are exceptional.b. A pessimistic protocol assumes it to be very likely that
Work out the compatibility matrix for the MGL Protocol, illustrating which requests can be granted given the locks currently held on a database object.
Which statement is correct?a. Multiple transactions may hold a shared lock on the same object.b. Multiple transactions may hold an exclusive lock on the same object.
Discuss the ACID properties of transaction management and the responsibility of the DBMS’s transaction management system to ensure this.
Which statement is not correct?a. Deadlock prevention can be achieved by static 2PL.b. One approach for deadlock resolution is victim selection, which means choosing and aborting one of the
According to the MGL Protocol…a. locks are acquired top-down, but released bottom-up in the hierarchy.b. locks are acquired bottom-up, but released top-down in the hierarchy.
Which of the following statements is not correct?a. Embedded database APIs can use early binding.b. Embedded database APIs can use late binding.c. Call-level database APIs can use early
Explain the differences between a centralized system and tiered system architecture.
Which of the following statements is not correct?a. One drawback of ODBC is that the architecture is mostly native to Microsoft-based platforms.b. One drawback of ODBC is that application code
What is meant by a “fat” client versus a “thin” one? Are web browsers fat or thin clients?
Which of the following statements is correct?a. JDBC drivers come in different types, which come with different tradeoffs in terms of portability and performance.b. JDBC was originally developed to
Explain the differences between “static” and “dynamic” SQL and how this relates to early and late binding.
Which of the following statements is not correct?a. Enterprise JavaBeans are components that establish a clear decoupling between business logic and client applications.b. Enterprise JavaBeans
DBMSs such as Microsoft Access, SQLite, and Apache Derby are often described as embedded databases. Does this mean they are accessed using embedded APIs? Explain why/why not.
Which of the following statements is not correct?a. The Java Persistence API arose as part of the specification of version 3.0 of the EJB standard.b. The Java Persistence API is in itself just a
OLE DB is often described as following a universal data access approach, rather than a universal data storage approach. What is meant by this?
One complaint against using JavaScript-heavy web applications that directly interface with a DBMS through REST or a similar technique is that they are, by default, less secure than using a
Which of the following statements is correct?a. The JPA query language (JPQL) supports more complex queries than SQL.b. JPQL queries can differ depending on the underlying DBMS used.c. One big
Which of the following statements regarding JPA is not correct?a. The JPA was meant as a replacement for entity Beans in EJB 2.0.b. JPA relies heavily on annotations and
Which statement is correct?a. In a shared-memory architecture, multiple interconnected processors that run the DBMS software share the same central storage and secondary storage.b. With a
Discuss the most important architectural variants of distributed databases.
With horizontal fragmentation…a. Each fragment consists of a subset of the columns of the global dataset.b. Each fragment consists of rows that satisfy a certain query predicate.
Illustrate vertical, horizontal, mixed, and derived fragmentation with an example.
Which statement is not correct?a. Location transparency means that database users do not need to know on which node the required data reside.b. Fragmentation transparency refers to the fact that
Discuss the different types of transparency in a distributed database environment.
Which statement is not correct?a. Primary site 2PL comes down to applying the centralized Two-Phase Locking Protocol in a distributed environment.b. A disadvantage of primary site 2PL is that the
Work out an example of distributed query processing.
A schedule in 2PL is deadlock free if…a. Both the local and global wait-for graphs contain no cycles.b. The local wait-for graphs contain no cycles.c. The global wait-for graph contains only a
Discuss and contrast the following locking approaches: primary site 2PL, primary copy 2PL, and distributed 2PL.
Optimistic concurrency may considerably increase transaction throughput and overall data availability in a…a. Tightly coupled setting.b. Loosely coupled setting.
Which of the following statements is not correct?a. CGI was one of the first technologies that allowed for the construction of dynamic web pages.b. CGI programs can be written in almost any
What are the different ways client-side applications can be enriched and made more interactive? Which technology stack is common today?
Which of the following is not a client-side scripting language?a. JavaScript.b. VBScript.c. JScript.d. PHP.
Which JDBC driver type is implemented completely in Java and communicates directly with the vendor’s DBMS through a network socket connection?a. Type 1.b. Type 2.c. Type 3.d. Type 4.
Which of the following statements is not correct?a. SQLJ uses a pre-compiler to translate embedded SQL statements before invoking the Java compiler.b. SQL syntax can be checked before runtime when
Which database access technique does the following C# statement illustrate?a. JDBC.b. ODBC.c. Language-integrated queries.d. None of the above. public void Example() { DataClassesContext dc = new
Discuss different techniques to detect conflicting updates in an optimistic concurrency setting.
Many NoSQL databases apply some form of…a. Vertical fragmentation.b. Horizontal fragmentation.
Discuss and illustrate a compensation-based transaction model.
Eventual consistency in a NoSQL environment implies that…a. The results of a database transaction will eventually be propagated to all replicas and if no further transactions are executed then the
What is meant by eventual consistency and BASE transactions?
With BASE transactions, conflict resolution…a. Always happens at the moment of writing the data.b. May be postponed until the data are actually read.
What is meant by multi-version concurrency control?
Quorum-based protocols essentially enforce consistency between replicas of the same data item by means of three configurable parameters N (the number of nodes to which a data item is replicated), R
What is quorum-based consistency? Illustrate with an example.
Which of the following statements is not correct?a. At the operational level, day-to-day business decisions are made, typically in real-time or with a short time frame.b. At the tactical level,
Contrast operational versus tactical versus strategic decision-making. Illustrate with examples in• An online retail setting (e.g., Amazon, Netflix, eBay);• A bank setting;• A university

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