CS 3306 Databases 2 - Study for Exam

What kind of properties can a deadline have?

- Hard - Firm - Soft

What do you need before doing a backup?

- Sensitive data to make it worth the effort. - Enough manpower to get the job done. - A backup plan. - A computer with sufficient hardware, as well as enough storage media. A backup plan.

In more recent times, mobile applications demand for certain types of data to be processed. Which ones?

- Temporal data - Spatial data - Multimedia data

Regression...

... deals with the prediction of a value.

One grain of dust...

... is enough to corrupt data when it gets between the head and disk of a hard drive.

Which of the following is an example for valid XML code?

<name> Humphrey Bogart </name>

What can be used to measure the performance of a database?

A benchmark

What is needed to achieve Serializability?

A concurrency-control scheme

What is a structure described in a formal language supported by the database management system?

A database schema

What kind of symbol is used in a diagram for a relationship set.

A diamond

What is a data query?

A piece of code that is understood by the DDL interpreter and returns data entries for further use.

In Role based access control, what does a role do?

A role controls access to the database according to certain user privileges.

What is PHP?

A server side scripting language

What subsystems does a DBMS have?

A transaction manager, a query processor and a storage manager.

What do you call a transaction that is responsible for a deadlock and has been chosen to be rolled back?

A victim

What is used to automatically control the execution of tasks?

A workflow-management system.

What can be said about the Precedence Graph T1 T2?

All T1 instructions must execute before the first T2 instruction executes.

What happens to data if the system crashes?

All of the data that were currently in the main memory are lost.

Why is it important that a transaction schedule should be serializable?

All serializable schedules preserve consistency of the database

Your company's data services are at risk because of a major power outage. What would be good to have right now?

An Uninterrupted Power Supply

In XML, what is an element?

An element is a pair of matching start and end tags and what is between them.

In databases, what is an example for a descriptive pattern?

Association

What properties should database transactions ideally have?

Atomicity, Consistency, Isolation, Durability (ACID)

What needs to happen as first step to connect to a database?

Authentication

What needs to be done with respect to personnel getting access to the database

Authorization and Authentication

Due to a malfunction in the coffee maker, your company's data center burns down. Fortunately, everything is safely stored elsewhere in a backup server. Which security objective still gets compromised?

Availability

Besides a plain list of numbers, what other format of Indices exist?

B-Tree Indices

What is the most important thing necessary for a successful disaster recovery (with respect to databases).

Backup

What do you call the component of a system that is responsible for limiting its performance?

Bottleneck

How can you test a schedule for conflict serializability?

By drawing a precedence graph. A schedule is conflict serializable if its precedence graph has no cycle.

What technique can be used if a web site receives high traffic by being accessed billions of times in one short interval?

Caching

What factors are commonly seen as important for finding the right backup solution?

Capacity, Reliability, Extensibility, Speed and Cost

What two main architectures are used in parallel processing?

Coarse-grain and fine-grain parallel machines

Often, even today, tape-based backup solutions are used for backup. What is their key advantage?

Cost effectiveness

What is the meaning of DDL?

Data Definition Language

What does the acronym DML stand for?

Data Manipulation Language

The task of correcting and preprocessing data is called...

Data cleansing

Which of the following is true?

Data-server systems allow clients to interact with the servers by making requests to read or update data, in units such as files or pages.

Database applications can be classified in two main types: Transaction Processing and...

Decision Support

When dealing with XML, what does DTD stand for?

Document Type Definition

Which is NOT a type of backup?

Dry

You are the database admin of your company. Unfortunately, your data center building is on fire. However, you took the best possible precautions and you can calm down your boss. Why?

Due to a smart disaster recovery plan, you stored a mirror version of the data in another building across town.

What is a simple rule to determining what are the "markup" elements of a document?

Everything that is only intended for machine-reading and not for printing, is markup.

What dependencies can be used as preconditions for executing a task?

Execution states, output values, external variables.

What does the acronym XML stand for?

Extensible Markup Language

True or false? If your hard drive starts failing, it's best to keep it running as long as possible and try everything you know to save the data.

False

What acronym is commonly used for the "Hypertext Transfer Protocol"?

HTTP

Which of the following is a commonly used type of interconnection system in parallel systems?

Hypercube

When does a deadlock happen?

If every transaction is waiting for another transaction to finish.

When is a transaction schedule legal?

If it follows the rules of the locking protocol that is in place.

What can be tuned to increase performance in a database system?

Indices

What is achieved by restricting values of data and operations on data?

Integrity Control

Which of the following is NOT a type of access or manipulation for data queries?

Interpretation of information stored in the database

In information retrieval, what can be used to locate a document that contains a certain keyword?

Inverted index

What does an XML schema do?

It constrains the values and data types of information present in a document.

What is the function of access control?

It controls access of the user to the database.

What is the purpose of a compensating transaction?

It helps to roll back a transaction without the risk of cascading rollbacks.

What is a transaction identifier?

It is the unique identifier of the transaction that performed the write operation.

Assume you have a workflow consisting of the subtransactions S1 and S2. S1 and S2 do not provide prepared-to-commit states (for a two-phase commit), and further do not have compensating transactions, and it is possible to reach a state where one subtransaction is committed and the other aborted, and there is no way to bring both to the same state. What can be said about such a workflow?

It is unsafe

What does a "process monitor process" do?

It monitors other processes, and if any of them fails, it takes recovery actions for the process.

What happens in the validation phase of a transaction?

It tests whether the transaction causes a violation of serializability.

What is the meaning of JDBC?

Java Database Connectivity

A transaction can be...

Killed

LBAC means Label-based Access Control. Regarding databases, an additional and more recent meaning of the same acronym has been established. What is it?

Lattice-based Access Control

Which is NOT a type of backup storage medium?

Liquid Crystal

What do you call a process that implements lock manager functionality, which includes lock grant, lock release, and deadlock detection?

Lock manager process

How does a database server deal with multiple requests from different clients?

Multithreading

What is the function of OLAP (Online Analytic Processing)?

OLAP tools provide interactive analysis of data, for example to help build decision support systems.

What is NOT an example of e-commerce?

Online Source Projects

Which of the following are the levels of data abstraction?

Physical level, logical level and view level

Which main objectives are relevant for database security?

Privacy, Integrity, Availability

What is a workflow?

Processing entities execute multiple tasks in a coordinated way.

When speaking of Role-based Access Control, which Acronym is typically used?

RBAC

Which of the following is NOT a data model?

Rational Model

What do you call systems with deadlines?

Real-time systems

What is likely to happen when you back up from multiple sources that may contain duplicate information to one backup file?

Redundancies

What are the three primary rules for RBAC?

Role assignment, role authorization, permission authorization

What would a basic SQL query look like?

SELECT * FROM DATA

What term describes the effect on a long transaction if a sequence of conflicting short transactions causes repeated restarting of the long transaction?

Starvation

What should you do to include natural disasters as possible risk to be mitigated by your backup plan?

Store data off-site.

What two important things do association rules have?

Support and Confidence

Which benchmark for database performance is NOT obsolete?

TPC-C

What is the name of a commonly used database model?

The Entity Relationship Model

What can be used in a SELECT statement to collect data across multiple records and group the results by one or more columns.

The GROUP BY statement

What is the function of the SQL GROUP BY statement?

The SQL GROUP BY clause can be used in a SELECT statement to collect data across multiple records and group the results by one or more columns.

What do you call the presentation layer of the internet that contains (usually visual) applications that help the user interact with databases and other content?

The World Wide Web (WWW)

What is the difference between an instance and a schema?

The collection of information stored in the database at a particular moment is called an instance of the database. The overall design of the database is called the database schema.

What is the difference between a differential backup and an incremental backup?

The differential backup backs up the data that are different from the previous full backup, while the incremental backup backs up the data that are different from the previous incremental or differential backup.

What is the difference between a full backup and a differential backup?

The full backup backs up all data, while the differential backup only backs up the difference from a previous full backup.

What is a Cardinality?

The number of how many entities in a database are associated with a given entity.

What happens if a human interacts with an active transaction?

The transaction becomes a long-duration transaction.

What is important for a workflow state?

The values of all variables in the workflow specification.

What is an advantage of concurrency?

The waiting time is reduced.

What can attributes of the type IDREF do?

They can store a list of references.

What is a namespace used for?

To specify a globally unique name to be used as element tag in documents.

In Databases, collections of operations that form a single logical unit of work are called...

Transactions

In today's database technology, what is the most common way to authenticate a user for access to a database?

Two-factor-Authentication

What does the acronym URL stand for?

Uniform Resource Locator

If you just save your data on a heap of CDs, DVDs and unlabeled thumb drives, this is, strictly speaking, also a form of backup. What is it called?

Unstructured Repository

What can be done to ensure that nearly full blocks are output (written to stable storage) by a transaction?

Using the group commit technique.

What is the difference between shared-mode and exclusive lock?

When there is a shared-mode lock, the transaction can read but not write the data item, where in an exclusive lock, the transaction can both write and read the data item.

You want to run a full backup of a hard drive in one of your company's computers. How do you best do that?

You create a mirror image of that hard drive and save it on a reliable storage medium.

If you wish to observe a database to ensure nothing strange happens with user access and the data, what do you best do as a first step?

You run a database audit

In DB2, what can the user with the SYSCTRL authority do?

create, update, start and stop the database

What trick can be used to improve database performance?

denormalized relation

Which elements does an object-oriented data model include?

encapsulation, methods (functions), and object identity

You want to determine the cardinality of a database that matches persons with (official) ID cards. From a government perspective, what would be the ideal cardinality for a relation Person - ID card?

one to one