Chapter 11Database Performance Tuning and
Query Optimization
Comprehensive Exam Study Guide Latest
Updated 2024/2025
100% Verified Guide
?
,Chapter 11Database Performance Tuning and
Query Optimization
Comprehensive Exam Study Guide Latest
Updated 2024/2025
100% Verified Guide
Chapter 11
Database Performance Tuning and Query Optimization
Discussion Focus
This chapter focuses on the factors that directly affect database performance. Because performance-
tuning techniques can be DBMS-specific, the material in this chapter may not be applicable under all
circumstances, nor will it necessarily pertain to all DBMS types.
This chapter is designed to build a foundation for the general understanding of database performance-
tuning issues and to help you choose appropriate performance-tuning strategies. (For the most current
information about tuning your database, consult the vendor’s documentation.)
Start by covering the basic database performance-tuning concepts. Encourage students to use the
web to search for information about the internal architecture (internal process and database
storage formats) of various database systems. Focus on the similarities to lay a common
foundation.
Explain how a DBMS processes SQL queries in general terms and stress the importance of
indexes in query processing. Emphasize the generation of database statistics for optimum query
processing.
Step through the query processing example in section 11-4, Optimizer Choices.
Discuss the common practices used to write more efficient SQL code. Emphasize that some
practices are DBMS-specific. As technology advances, the query optimization logic becomes
increasingly sophisticated and effective. Therefore, some of the SQL practices illustrated in this
chapter may not improve query performance as dramatically as it does in older systems.
Finally, illustrate the chapter material using the query optimization example in section 11-8.
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,Chapter 11Database Performance Tuning and
Query Optimization
Comprehensive Exam Study Guide Latest
Updated 2024/2025
100% Verified Guide
401
?
, Chapter 11Database Performance Tuning and
Query Optimization
Comprehensive Exam Study Guide Latest
Updated 2024/2025
100% Verified Guide
Chapter 11
Database Performance Tuning and Query Optimization
Answers to Review Questions
1. What is SQL performance tuning?
SQL performance tuning describes a process – on the client side – that will generate an SQL query
to return the correct answer in the least amount of time, using the minimum amount of resources at
the server end.
2. What is database performance tuning?
DBMS performance tuning describes a process – on the server side – that will properly configure the
DBMS environment to respond to clients’ requests in the fastest way possible, while making
optimum use of existing resources.
3. What is the focus of most performance tuning activities, and why does that focus exist?
Most performance-tuning activities focus on minimizing the number of I/O operations, because the
I/O operations are much slower than reading data from the data cache.
4. What are database statistics, and why are they important?
The term database statistics refers to a number of measurements gathered by the DBMS to describe
a snapshot of the database objects’ characteristics. The DBMS gathers statistics about objects such
as tables, indexes, and available resources -- such as number of processors used, processor speed,
temporary space available, and so on. Such statistics are used to make critical decisions about
improving the query processing efficiency.
5. How are database statistics obtained?
Database statistics can be gathered manually by the DBA or automatically by the DBMS. For
example, many DBMS vendors support the SQL’s ANALYZE command to gather statistics. In
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