Question 1

Maximizing disk contention is one of the general recommendations for the physical storage of databases.

Accepted Answer

Maximizing disk contention can lead to performance issues and is not recommended for the physical storage of databases. Instead, it is recommended to minimize disk contention by distributing database files across multiple disks and using RAID configurations.

Question 2

Fully equivalent means that the optimized query results are always the same as the original query.

Accepted Answer

Fully equivalent means that the optimized query produces the same results as the original query, so the answer is True.

Question 3

RAID systems use a single disk to create storage volumes.

Accepted Answer

RAID systems use multiple disks to create storage volumes, not a single disk.

Question 4

A table space has the same meaning as a file extent.

Accepted Answer

A table space is a logical container for a set of tables, indexes, and other database objects. A file extent is a portion of a physical file used by a database to store data. They serve different purposes in a database system.

Question 5

All factors must be checked to ensure that each system component operates at its optimum level and has sufficient resources to minimize the occurrence of bottlenecks.

Accepted Answer

This statement is true. All factors must be checked to ensure that each system component operates at its optimum level to prevent bottlenecks. This includes checking for sufficient resources such as RAM, CPU, and disk space.

Question 6

An index scan is less efficient than a full table scan.

Accepted Answer

This statement is false. A full table scan involves reading every row in a table, whereas an index scan only involves reading the relevant index entries. In many cases, an index scan can be more efficient than a full table scan, especially when retrieving a small subset of rows from a large table.

Question 7

The purpose of an I/O operation is to move data to and from different computer components or devices.

Accepted Answer

The purpose of I/O operations is to transfer data between different components or devices in a computer system. This includes input devices (e.g. keyboard, mouse) and output devices (e.g. monitor, printer), as well as storage devices such as hard drives or flash drives.

Question 8

The SQL cache stores the end-user written SQL.

Accepted Answer

The SQL cache, often referred to as the query cache, stores the results of executed SQL queries rather than the end-user written SQL itself. This allows for faster retrieval of data if the same query is executed again, without the need to re-process the query.

Question 9

To work with data, the DBMS must retrieve the data from permanent storage and place it in RAM.

Accepted Answer

This statement is true as the DBMS needs to access the data from permanent storage like a hard disk and load it into RAM for processing.

Question 10

Good database performance is easy to evaluate.

Accepted Answer

Evaluating database performance requires a thorough understanding of the system's architecture, workload characteristics, and performance metrics, making it a complex task.

Question 11

One of the main functions of a database system is to provide timely answers to end users.

Accepted Answer

One of the primary purposes of a database system is to efficiently provide accurate and timely information to end-users. The system allows for efficient data retrieval, storage, and organization, ultimately allowing for quicker data retrieval and analysis.

Question 12

DBMS implementations are typically similar in complexity to two-tier client/server configurations.

Accepted Answer

DBMS implementations can vary significantly in complexity and are not necessarily similar to the complexity of two-tier client/server configurations. DBMS architectures can range from simple single-user databases to complex multi-tiered systems that serve multiple concurrent users and applications.

Question 13

The B-tree index is used mainly in tables in which column values repeat a relatively small number of times.

Accepted Answer

The B-tree index is designed to handle high-cardinality data, where there are a large number of distinct values in a column. It is not ideal for columns with a small number of repeating values.

Question 14

Indexes do not facilitate join operations.

Accepted Answer

Indexes can facilitate join operations by improving the performance of the query. When both the tables involved in the join have indexes on the join columns, the join operation can be performed more efficiently.

Question 15

The SQL execution activities are performed by the query optimizer.

Accepted Answer

The query optimizer is responsible for creating an efficient execution plan for SQL queries, but the actual execution of these plans is performed by the database engine.

Question 16

The data cache caches system catalog data and the contents of the indexes.

Accepted Answer

The data cache is used to cache system catalog data and the contents of indexes, allowing for faster access to frequently-accessed data.

Question 17

Most current-generation relational DBMSs perform automatic query optimization at the client end.

Accepted Answer

Most current-generation relational DBMSs perform automatic query optimization at the server end, not the client end.

Question 18

The primary factor in determining the most efficient access plan is the I/O cost.

Accepted Answer

The primary factor in determining the most efficient access plan is the I/O cost, as minimizing the number of I/O operations required to retrieve or modify data can greatly improve system performance. Other factors, such as the size and complexity of the data, the available memory and processing power, and the concurrency requirements of the application, may also play a role in determining the optimal access plan, but they are usually secondary to the I/O cost.

Question 19

All transaction management commands are processed during the parsing and execution phases of query processing.

Accepted Answer

Transaction management commands are processed during the parsing and execution phases of query processing.

Question 20

Working with data in the data cache is many times faster than working with data in the data files.

Accepted Answer

Data in the cache is stored in memory, which can be accessed much faster than data stored on disk in data files. Therefore, working with data in the cache is generally much faster than working with the same data in the data files.

Quiz 11: Database Performance Tuning and Query Optimization