CHAPTER 11: DATABASE PERFORMANCE TUNING AND QUERY
OPTIMIZATION
1. One of the main functions of a database system is to provide timely answers to end users.
a. True
b. False
2. Good database performance is easy to evaluate.
a. True
b. False
sufficient resources to minimize the occurrence of bottlenecks.
a. True
b. False
a. True
b. False
5. DBMS implementations are typically similar in complexity to two-tier client/server configurations.
a. True
b. False
6. A data file can contain rows from a single table alone.
a. True
b. False
7. The data cache caches system catalog data and the contents of the indexes.
a. True
b. False
8. The SQL cache stores the end-user written SQL.
a. True
b. False
Chapter 11: Database Performance Tuning and Query Optimization
9. To work with data, the DBMS must retrieve the data from permanent storage and place it in RAM.
a. True
b. False
10. The purpose of an I/O operation is to move data to and from different computer components or devices.
a. True
b. False
11. Working with data in the data cache is many times faster than working with data in the data files.
a. True
b. False
a. True
b. False
13. The SQL execution activities are performed by the query optimizer.
a. True
b. False
14. All transaction management commands are processed during the parsing and execution phases of query
processing.
a. True
b. False
15. An index scan is less efficient than a full table scan.
a. True
b. False
a. True
b. False
Chapter 11: Database Performance Tuning and Query Optimization
17. Using index characteristics, a database designer can determine the best type of index to use.
a. True
b. False
a. True
b. False
19. A cost-based optimizer uses a set of preset rules and points to determine the best approach to execute a query.
a. True
b. False
20. Most current-generation relational DBMSs perform automatic query optimization at the client end.
a. True
b. False
21. Indexes are very useful in small tables or tables with low sparsity.
a. True
b. False
22. Character field comparisons are faster than numeric, date, and NULL comparisons.
a. True
b. False
23. Maximizing disk contention is one of the general recommendations for the physical storage of databases.
a. True
b. False
24. RAID systems use a single disk to create storage volumes.
a. True
b. False
Chapter 11: Database Performance Tuning and Query Optimization
25. In-memory database systems are optimized to store small portions of the database in disk storage alone.
a. True
b. False
26. DBMS performance tuning includes global tasks such as managing the DBMS processes in primary memory
and managing the structures in physical storage.
a. True
b. False
27. On the client side, the objective is to generate an SQL query that returns a correct answer in the least amount of
time, using a minimum amount of resources at the server end. The activities required to achieve this goal are
commonly referred to as tuning.
a. client SQL b. database SQL
c. SQL performance d. DBMS performance
28. On the server side, the database environment must be properly configured to respond to clients’ requests in the
fastest way possible, while making optimum use of existing resources. The activities required to achieve this
goal are commonly referred to as tuning.
a. client and server b. database SQL
c. SQL performance d. DBMS performance
29. When moving data from permanent storage to RAM, an I/O disk operation retrieves:
a. an entire table. b. an entire physical disk block.
c. only the row containing the attribute requested. d. only the attribute which was requested.
30. A DBA determines the initial size of the data files that make up the database; however, as required, the data
files can automatically expand in predefined increments known as .
a. procedure cache b. buffer cache
c. supplements d. extends
31. A(n) is a logical grouping of several data files that store data with similar characteristics.
a. procedure cache b. table space
c. data cache d. listener
Chapter 11: Database Performance Tuning and Query Optimization
32. A system table space, a user data table space, an index table space, and a temporary table space are examples of
_____.
a. procedure caches b. file groups
c. data caches d. operation modes
33. The data cache is where the data read from the database data files are stored the data have been read
or the data are written to the database data files.
a. after; before b. after; after
c. before; before d. before; after
34. To work with data, a DBMS must retrieve the data from and place them in .
a. data files; procedure cache b. RAM; data cache
c. permanent storage; RAM d. temporary files; procedure cache
35. The data cache or is a shared, reserved memory area that stores the most recently accessed data blocks
in RAM.
a. buffer cache b. procedure cache
c. SQL cache d. permanent storage
36. The is a shared, reserved memory area that stores the most recently executed SQL statements or
PL/SQL procedures, including triggers and functions.
a. buffer cache b. procedure cache
c. data cache d. permanent storage
37. To generate database object statistics manually, following syntax should be used in Oracle: .
a. ANALYZE <TABLE/INDEX> object_name;
b. CREATE <TABLE/INDEX> object_name;
c. ANALYZE <TABLE/INDEX> object_name COMPUTE STATISTICS;
d. CREATE <TABLE/INDEX> object_name COMPUTE STATISTICS;
38. The process analyzes SQL queries and finds the most efficient way to access data.
a. optimizer b. scheduler
c. listener d. user
Chapter 11: Database Performance Tuning and Query Optimization
39. Automatic query optimization means that the:
a. optimization takes place at compilation time by the programmer.
b. DBMS finds the most cost-effective access path without user intervention.
c. optimization process is scheduled and selected by the end user or programmer.
d. database access strategy is defined when the program is executed.
40. The DBMS the SQL query and chooses the most efficient access/execution plan.
a. parses b. executes
c. fetches d. processes
41. Which of the following is the first step of query processing at the DBMS server end?
a. Executing b. Parsing
c. Fetching d. Delivering
42. The DBMS the data and sends the result set back to the client.
a. parses b. executes
c. fetches d. processes
43. If there is no index, the DBMS will perform a scan.
a. loop b. range
c. row ID table access d. full table
44. refers to the number of different values a column could possibly have.
a. Database statistics b. Data sparsity
c. A bitmap index d. Clustering
45. Bitmap indexes tend to use less space than a because they use bits instead of bytes to store their data.
a. hash index b. sparse index
c. B-tree index d. reverse index
46. Knowing the sparsity of a column helps you decide whether the use of is appropriate.
a. query processing b. query optimization
c. an index d. a full table scan
Chapter 11: Database Performance Tuning and Query Optimization
47. is the central activity during the parsing phase in query processing.
a. Clustering b. Partitioning
c. Query validation d. Query optimization
48. When setting optimizer hints, instructs the optimizer to minimize the overall execution time, that is, to
minimize the time it takes to return the total number of rows in the query result set. This hint is generally used
for batch mode processes.
a. ALL_ROWS b. FIRST_ROWS
c. INDEX(P_QOH_NDX) d. OPTIMIZATION_ROWS
49. In standard SQL, the optimizer hint FIRST_ROWS is generally used for mode processes.
a. batch b. interactive
c. transaction d. real-time
50. In standard SQL, the optimizer hint ALL_ROWS is generally used for mode processes.
a. interactive b. real-time
c. batch d. transaction
51. The LIKE conditional operator is used by the OPERAND1.
a. P_PRICE b. V_STATE
c. P_QOH d. V_CONTACT
52. The must be set large enough to permit as many data requests to be serviced from cache as possible.
a. data cache b. SQL cache
c. sort cache d. optimizer mode
53. The majority of primary memory resources will be allocated to the cache.
a. data b. SQL
c. sort d. optimizer
54. The cache stores the most recently executed SQL statements.
a. data b. procedure
c. sort d. optimizer
Chapter 11: Database Performance Tuning and Query Optimization
55. The cache is used as a temporary storage area for ORDER BY or GROUP BY operations, as well as for
index-creation functions.
a. data b. SQL
c. sort d. optimizer
56. From the performance point of view, databases eliminate disk access bottlenecks.
a. RAID b. distributed
c. index-organized d. in-memory
57. The table space is used for transaction-recovery purposes.
a. system b. user data
c. temporary d. rollback segment
58. In the context of RAID levels, refers to writing the same data blocks to separate drives.
a. striping b. mirroring
c. partitioning d. aggregating
59. The table space is used to store the data dictionary tables.
a. system b. user data
c. temporary d. rollback segment
60. In the context of RAID levels, striped arrays provide:
a. increased read performance and fault tolerance. b. increased fault tolerance but decreased performance.
c. increased read performance but no fault tolerance. d. neither fault tolerance nor good performance.
61. In RAID level 5,:
a. the data and the parity data are striped across separate drives.
b. the data blocks are spread over separate drives and are duplicated.
c. the array requires a minimum of two drives and is known as a striped array.
d. the array requires a minimum of five drives and is known as duplexing.
62. End users and the DBMS interact through the use of to generate information.
Chapter 11: Database Performance Tuning and Query Optimization
63. A system will perform best when its hardware and software resources are .
64. Database activities can be divided into those taking place either on the client side or on the server side.
65. is another name for table space.
66. The cache is a shared, reserved memory area that stores the most recently executed SQL statements or
PL/SQL procedures, including triggers and functions.
67. A(n) request is a low-level read or write data access operation to or from computer devices.
68. DBMS query processing has phases.
69. The analyzes the SQL query and finds the most efficient way to access the data.
70. Once an SQL statement is transformed, the DBMS creates what is commonly known as a(n) plan.
71. are ordered sets of values that are crucial in speeding up data access.
72. A is good for simple and fast lookup operations based on equality conditions.
73. are special instructions for the optimizer that are embedded inside the SQL command text.
74. is a measure of the likelihood that an index will be used in query processing.
75. is evaluated based on client perspective.
Chapter 11: Database Performance Tuning and Query Optimization
76. is an index based on a specific SQL function or expression.
77. A conditional expression is normally expressed within the or HAVING clauses of a SQL statement.
78. helps provide a balance between performance and fault tolerance.
79. The table space is the most frequently accessed table space and should be stored in its own volume.
80. List and describe some typical DBMS processes.
81. Describe query optimization and the modes that an optimizer can operate in.
Chapter 11: Database Performance Tuning and Query Optimization
82. Why do we need to optimize a DBMS with SQL performance tuning, even though they automatically optimize
SQL queries?
83. How can queries be written to perform the fastest when equality and inequality comparisons are needed?
84. Summarize the steps required to formulate a query.
Chapter 11: Database Performance Tuning and Query Optimization
85. How should storage volumes be allocated for indexes, system, and high-usage tables?