VITEC Database Systems Engineer Examination (Morning)

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3. Mark your examinee information and test answers in accordance with the instructions below. (1) Use an HB black pencil. If you need to change an answer, fully erase the undesired mark with a rubber eraser until no mark remains

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Nội dung Text: VITEC Database Systems Engineer Examination (Morning)

October, 2005 VITEC Database Systems Engineer Examination (Morning) 1. Examination Time-9:00-10:30 (90 minutes). 2. Questions must be answered in accordance with the following: Question Nos. Q1-Q50 Question Selection All questions are compulsory 3. Mark your examinee information and test answers in accordance with the instructions below. (1) Use an HB black pencil. If you need to change an answer, fully erase the undesired mark with a rubber eraser until no mark remains. Remove rubber bits on the paper. (2) Answer sheets are processed through an optical reader. Mark your answers according to the answer sheet marking method given in (5) below. (3) Fill in and mark the test number in the test number area. If an answer is not marked correctly, or is marked differently than explained in (5), your test cannot be scored. (4) In the Date of Birth area, fill in your Date of Birth exactly as printed on your test form. If this item is not marked correctly, your test cannot be scored. (5) Mark only one answer for each question, as shown in the example below. Example: In what month is the Spring Information Processing Engineer Exam held? a) February b) March c) April d) May Since the correct answer is “c” (April), mark your answer sheet as follows: [Sample Reply] d) a) b) 4. After you complete and turn in your exam, you can take this question booklet home with you. Do not open the exam booklet until instructed to do so. Inquiries about the exam questions will not be answered.
Company names and product names appearing in the test questions are trademarks or registered trademarks of their respective companies. Note that the ® and ™ symbols are not used within.
Q1 Which system attempts to speed up data transfer to an auxiliary storage device equipped with the channel control system of a general-purpose computer, by continually sending data without waiting for a confirmation signal? a) Serial system b) Streaming system c) Parallel system d) Handshake system Q2 Which of the following is a von Neumann bottleneck (a factor that prevents performance improvement with a computer that sequentially fetches and executes program instructions in the CPU)? a) Main memory capacity b) Data transfer capacity between an internal device (processor and main memory) and an I/O device c) Data transfer capacity between a processor and the main memory d) Processor performance Q3 Which of the following is a correct statement concerning virtual storage systems? a) An LRU algorithm is a page-replacing algorithm that replaces the page for which the the longest time has elapsed since it was last used. b) To convert an address by indexing requires a page table of all pages in the main memory. c) When a page fault occurs, garbage collection is required. d) Fragmentation occurs when many small areas of available memory are created during repeated paging. -1-
Q4 Which of the following is a correct statement concerning OS scheduling methods? a) In the processing time-sequenced method, higher priority is given to the job that has already consumed a larger amount of CPU time. b) Response time, for jobs requiring particularly short processing time, is much shorter in the arrival-sequenced method in comparison with the round robin method. c) In the priority-sequenced method, the response time of some jobs can be extremely long. d) The shorter the CPU time (time quantum) allocated to a job in the round robin method, the closer the method is to the arrival-sequenced method. Q5 Which of the following is a correct statement in regard to a preemptive system in OS process control? a) Each process can manage system resources autonomously, so the preemptive system is well-suited to multi-programming. b) The preemptive system has less context switching overhead than the non-preemptive system. c) In the preemptive system, certain processes monopolize the processor more frequently than in the non-preemptive system. d) Realizing a preemptive system requires a mechanism whereby the OS can forcefully switch and execute processes. Q6 Which of the following systems offers the best results in introducing a three-tier client-server architecture? a) A system with a small number of application services and classes b) A system where correction and addition of applications are frequent c) A system in which all applications are written in the same language d) A system with a comparatively small number of transactions Q7 -2-
A device provides services at a rate of 5 sec per transaction on the average. What is the least number of devices needed to bring device usage rate below 0.5 sec, even when the average arrival is 20 transactions per minute? a) 2 b) 3 c) 4 d) 5 Q8. A system sends data from a server to a magnetic disk device over a LAN at a data transfer rate of 10 Mbps. The table below gives the measured transfer speed of the server and the measured reception speed of the client for differing numbers of clients to which the server simultaneously sends data. From these results, it can be seen that server transfer speed does not increase over 300 Kbps when there are 2 or more clients. Which of the following is the most likely cause of this? In all of these measurements, the server and all of the clients have sufficient CPU performance and memory capacity. Data transfer rate (Kbps) Measurement Number of Average for server Average per client case clients (Transfer) (Reception) Case 1 1 150 150 Case 2 2 300 150 Case 3 3 300 100 a) Insufficient data transfer capacity of the LAN itself b) Insufficient capacity of the client’s LAN connection interface mechanism c) Insufficient capacity of the client’s magnetic disk device d) Insufficient capacity of the server’s LAN connection interface mechanism Q9 If the performance of a single CPU is 1, then the performance P of a multiprocessor containing n these CPUs is expressed as: In this formula, a is a constant which expresses the overhead. For example, if a = 0.1 and n = 4, then P 3, so the performance of a multiprocessor consisting of 4 CPUs is approximately 3. The multiprocessor performance expressed in this equation has an upper limit. It will not increase beyond a certain value no matter how large a number n may be. What is this value if a = 0.1? a) 5 b) 10 c) 15 d) 20 Q10 -3-
Which of the following correctly expresses the MTBF and MTTR of the system in the work model diagram below? Here, ti is the system running time and ri is the system repair time (i = 1, 2, …, n). Failure Failure Failure Running Running Running Running Repair Repair Repair MTBF MTTR a) b) c) d) Q11 Which of the following statements correctly describes a technology used to increase the reliability of a computer system? a) “Failsafe” is a technology that reduces failure by increasing the reliability of individual components. b) “Failsoft” is a technology for handling system faults caused by software. c) “Fault avoidance” is a technology that enables operations to continue even if a failure occurs in a component. d) “Fault tolerance” is a technology, whereby critical parts which form a system are installed redundantly, to cope with the occurrences of failures. Q12 -4-
Which of the following statements correctly describes data mining? a) Its primary objective is the analysis of time-series data which do not involve update processes, created separately from the core operations database. b) It analyzes customized data that are extracted according to the analyzer’s objectives, such as personal data, departmental data, and summary data. c) It performs multidimensional analysis through interactive operations such as slicing, dicing, and drilling down in order to support decision-making. d) It creates theories, such as customer purchasing behaviors, from large amounts of stored data using neural networks, statistical analysis, and other techniques. Q13 Which of the following is the correct expression of the recall ratio and precision ratio used as measures in evaluating information retrieval systems, such as document retrieval systems and data retrieval systems? Here, A, B and C indicate the following. A: The number of data cases amongst all accumulated data that are suitable to the inquiry B: The number of data cases amongst retrieved data that are suitable to the inquiry C: The number of data cases retrieved Recall ratio Precision ratio a) A/B B/C b) B/A B/C c) B/A C/B d) C/B A/B Q14 Which of the following is a correct statement concerning “frames” as a method for expression of knowledge? a) Its format consists of expression of concepts as nodes, and relations or characteristics as directional arcs. b) It has an IF-THEN format to express conditions and behavior. c) Its format comes from a correspondence list of slot-to-slot values. d) Its format consists of proposition logic and predicate logic. Q15 Which of the following correctly defines a repository in software development? -5-
a) It is a database of software components provided to support development. b) It is a database that centrally manages design information and program information in software development and maintenance. c) It is a database for storing software development tools and data models. d) It is a database for storing source program analysis software and analysis results for reverse engineering. Q16 Which of the following is a correct statement in regard to prototyping? a) It is more suitable for batch systems than GUI-based interactive systems. b) Effectiveness can be increased by repeatedly remaking the prototype. c) It assumes there are frequent requirement specification changes, so it cannot be used in the waterfall model. d) It is not suited for the development of systems with a long life cycle or for packages to be used by many people. Q17 Which of the following is a correct statement concerning inheritance in object orientation? a) When a subclass is defined under a given class, the data structures and procedures defined in the higher class can be inherited and used in the subclass. b) Data structures and values determining an object’s characteristics are hidden and direct access from outside the object is prohibited. c) Even if an object’s data structure or processing method is changed, impact to the outside can be avoided, allowing the object’s independence to be improved. d) It expresses objects having identical data structures and identical procedures all together. Q18 Which of the following is a correct statement in regard to black box tests? -6-
a) Test case coverage is used as a criterion for creating test data. b) Even if the tested program contains redundant code, it cannot be detected. c) A black box test focuses on a program’s internal structure and verifies whether the required parts have been executed. d) Test data increases significantly as the numbers of branch instructions and modules increase. Q19 There is a database in which data additions, changes, and deletions occur at a certain low frequency. The interval between backups has been increased to twice the current level for backing the database onto magnetic tape. Which of the following is a correct statement with respect to the database operations? a) The average recovery time from journal information will increase by a factor of approximately 2. b) The database capacity will increase by a factor of approximately 2. c) The number of magnetic tapes required for a single backup will decrease by approximately one-half. d) The average backup execution time will increase by a factor of approximately 2. Q20 Which of the following correctly describes an ANSI/SPARC schema of a three-layer structure that defines all of the real world data required in data processing and a data structure that does not depend on a special application program? a) Conceptual schema b) External schema c) Subschema d) Internal schema Q21 Which of the following statements correctly describes a conceptual data model? -7-
a) It includes a hierarchical model, network model and relational model. b) It abstractly expresses a job process. c) Its content differs depending on whether a centralized DBMS is introduced or a distributed DBMS is introduced. d) It expresses information requirements of the target world. Q22 When comparing a relational database with an object-oriented database, which of the following statements correctly describes the object-oriented database? a) It can express real world information as a modelled class hierarchy and, by using this class hierarchy, it can separately handle data and operations. b) It encapsulates data and procedures, and handles them as a single unit, therefore it can handle complicated objects that contain operations. c) Data manipulation and relations are mathematically defined, therefore it is independent of programming languages and data manipulation languages. d) It defines relations by logical data structure, therefore it can perform data operations using non-procedural manipulation language. Q23 Which of the following is the correct combination of terms to insert in the blanks A C through in the following statement describing the features of logical data models? The hierarchical model and the network model express the relationship between entities as combinations of parent-child relationships. In the hierarchical model, a single child has A B , while in a network model, a single child has . On the other hand, a relational model is based on a mathematical set concept; the relation between one row in a table C and a row in another table is done using . A B C a) always one parent multiple parents the same value b) always one parent multiple parents a pointer c) multiple parents always one parent the same value d) multiple parents always two parents a pointer Q24 -8-
Which of the following expresses the breakdown of table X into a Boyce/Codd normalization? Here, x → y means y is functionally dependent on x. X Functional dependencies existing in table X ab → c (a, b, c, d, e) ab → d ab → e c→d e→a a) (a, b, c), (c, d), (e, a) b) (a, b, c, d), (e, a) c) (a, b, c, e), (c, d) d) (a, b, c, e), (c, d), (e, a) Q25 Which of the following is a correct statement with respect to functional dependency? Here, A, B and C are groups of attributes of a particular relation. a) If B functionally depends on A and C functionally depends on A, then C functionally depends on B. b) If B is a subset of A and C functionally depends on A, then C functionally depends on B. c) If B is a subset of A , then A functionally depends on B. d) If the sum of B and C functionally depends on A, then each of B and C functionally depends on A. Q26 -9-
Which of the following is the correct combination of 1st, 2nd and 3rd normal forms, and their features A, B and C? A: All non-key attributes entirely depend on the primary key. B: No non-key attributes are transitionally functionally dependent. C: There is no repetition of attribute values. 1st normal form 2nd normal form 3rd normal form a) A B C b) A C B c) C A B d) C B A Q27 How far is the following table normalized? Employee Year of Name Position Allowance No. employment 12345 Mike Gordon 1961 Dept. manager 900 12346 William Smith 1975 Section chief 500 12347 Mary Carpenter 1977 Section chief 500 a) To the 2nd b) To the 3rd c) To the 4th d) Not normal form normal form normal form normalized Q28 How many different projections are there of a relation which has n attributes? Here, the number of projections includes those with the same result as the original relation as well as those that do not have any attributes. b) 2n a) 2n c) log2 n d) n Q29 - 10 -
Job rules are given as follows. A data model was created on the basis of these rules. Which one is the correct data model? Here, 1 * represents the cardinality of one to many. (Job rules) This company sells diverse language educational materials such as textbooks, dictionaries, etc. Sales persons are assigned multiple sales areas, and take orders from customers in the assigned areas. Multiple sales persons are in charge of a single sales area. Area Sales persons a) Sales area Customer Order-taking Educational Order slip materials Customer Sales persons b) Area Sales area Order-taking Educational Order slip materials Customer Area c) Sales area Sales persons Order-taking Educational Order slip materials Area Sales area d) Customer Sales persons Order-taking Educational Order slip materials Q30 - 11 -
A conceptual data model of an organizational hierarchy of multiple divisions, departments, sections and groups was constructed as a 3rd normal form table: organization (organization_ID, organization_name ...). Which condition completes the blank below as the SQL statement that expresses the parent-child relations of the organization? Here, the underlined part of the “organization” description represents the primary key and it is necessary to assume additional attributes. The “*” of multiplicity in the conceptual model represents 0 or greater, whereas 1 is assumed where no mark is given. The role is written on the target side of the association line. {Hierarchy} is a restriction notation that indicates that the organization hierarchy neither loops nor forms a network. {Hierarchy} Child organization Organization Organization name ... Parent organization SELECT organization_1.organization_name AS parent_organization, organization_2.organization_name AS child_organization FROM organization AS organization_1, organization AS organization_2 WHERE a) organization_1.parent_organization_ID = organization_2.child_organization_ID b) organization_1.parent_organization_ID = organization_2.organization_ ID c) organization_1.organization_ID = organization_2.parent_organization_ ID d) organization_1.organization_ID = organization_2.child_organization_ID Q31 - 12 -
The following SQL statement is a cursor declaration for reading records in table A with a COBOL program. Which statement will correctly complete the blank ? a) EXEC SQL DECLARE C1 CURSOR FOR b) EXEC SQL DECLARE CURSOR FOR C1 c) EXEC SQL OPEN CURSOR C1 FOR d) EXEC SQL OPEN CURSOR DECLARE C1 FOR Q32 Which of the following is a correct statement concerning the trigger in a relational database? a) It is activated when a reference command is issued. b) It is activated when data is changed. c) It is not activated by another trigger. d) It is activated when rollback processing is executed. - 13 -
Q33 Four views were created of an “Order” table and a “Product” table. Which of these views can be updated? Order Product Order Customer Customer Product Total Product Product Unit Order date Quantity No. ID name code price code name price 001 1999-06-05 K111 Company A RX01 5 1,500 F001 Refrigerator 750 001 1999-06-05 K111 Company A RY01 10 2,900 RX01 Radio X 300 001 1999-06-05 K111 Company A F001 5 3,750 RY01 Radio Y 290 002 1999-06-10 K222 Company B TV18 10 4,500 TV18 TV 450 003 1999-06-15 K333 Company C TV18 5 2,250 003 1999-06-15 K333 Company C F001 2 1,500 004 1999-06-20 K222 Company B RY01 5 1,450 004 1999-06-20 K222 Company B F001 2 1,500 a) CREATE VIEW customer_V (customer_ID, customer_name) AS SELECT DISTINCT customer_ID, customer_name FROM order b) CREATE VIEW products_V (product_code, product_name) AS SELECT product_code, product_name FROM product c) CREATE VIEW orders_V (order_No., order_date, customer_ID, total_price) AS SELECT order_No., order_date, customer_ID, SUM (total_price) FROM order GROUP BY order_No., order_date, customer_ID d) CREATE VIEW order_detail_V (order_No., product_code, quantity, unit_price, total_price) AS SELECT order_No., orders_product_code, quantity, unit_price, total_price FROM order, product WHERE orders.product_code = products.product_code Q34 - 14 -
What combination of relational operations of union, difference, direct product, projection and selection expresses the following SQL statement? Here, the primary key is underlined. SELECT delivery.customer_ID, customer_name FROM delivery, customer WHERE delivery.customer_ID = customer.customer_ID Delivery Customer product_code customer_ID delivery_quantity customer_ID customer_name a) difference, selection, projection b) difference, direct product, selection c) direct product, selection, projection d) union, direct product, projection Q35 Which of the following is the correct syntax for the SQL statement? a) SELECT order_No, AVG (quantity) FROM order_detail b) SELECT order_No, AVG (quantity) FROM order_detail GROUP BY order_No c) SELECT order_No, AVG (SUM (quantity)) FROM order_detail GROUP BY order_No d) SELECT order_No FROM order_detail WHERE SUM (quantity) > 1000 GROUP BY order_No Q36 - 15 -
Which of the following is a correct statement in regard to 2-phase locking protocols used in the simultaneous execution control of transactions? a) In the 2-phase locking protocol, shared lock or exclusive lock concepts do not exist. b) If in different tables, it is OK to lock a transaction after unlocking it. c) Deadlocks cannot be prevented. d) It is not necessary to lock transactions that perform read operations. Q37 The figure below illustrates the normal processing flow of a 2-phase commitment protocol in a distributed system. Which combination of statements correctly describes operations through ? System A System C System B Transaction start Data transfer for transaction Transaction end processing start Unlock execute Unlock execute Commit execute Commit execute a) command reply command reply Commit enable Commit enable Commit execute Commit execute b) inquiry reply command reply Commit execute Commit execute Unlock execute Unlock execute c) command reply command reply Journal acquisition Journal Commit execute Commit execute d) command acquisition reply command reply Q38 - 16 -
Which of the following is a correct statement with respect to “transparency of transfer”, which is one of the objectives of a distributed database system? a) Even if the site where a table is stored has been changed due to an operational problem or for the purpose of improving the performance, the user can use the system without being aware of this. b) Even if the database is physically distributed via a communication network, the system can be used without making the user aware of the distributed configuration. c) Even if a single table is duplicated and stored at multiple sites, the user can use the table without being aware of this. d) Even if a table is split up and stored at multiple sites, the user can use the table without being aware of this. Q39 Program B uses a static SQL statement to access table A in a relational DBMS for reading only. The access module that Program B uses for the DBMS was created when there was no data item, immediately after table A had been created. Subsequently, more than 100,000 data items were added to table A. To improve a deteriorating response in Program B, it was decided to tune the program. In this situation, what should be done and how? In table A, an ascending cluster index is assigned to the primary key, while the DBMS decides the access path at the time the access module is created, based on the statistical information in the table. (1) Reorganize the storage area where table A exists. (2) Delete, then recreate the cluster index for table A. (3) Acquire statistical information on table A and the storage area from the DBMS. (4) Recreate the access module of Program B. a) (1) → (3) → (4) b) (2) → (1) → (3) c) (2) → (3) → (4) d) (3) → (4) → (2) Q40 - 17 -
Which of the following statements correctly describes the ACID feature of a transaction? a) In addition to generating a state where all processing that should be executed for the transaction is performed or no processing is performed at all, it also generates a state where some parts of the processing is performed. b) If a failure occurs, execution results can be lost even after the end of the execution of the transaction. c) Execution results of the transaction are never contradictory. d) Transactions are interrelated and are effected by other transactions that are executed simultaneously. Q41 Which of the following isolation levels has the highest interference tolerance between transactions? a) Repeatable read b) Read uncommitted c) Read committed d) Serializable Q42 - 18 -