Database Reference
In-Depth Information
10
Performance &
Concurrency
In this chapter, we will cover the following:
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Finding slow SQL statements
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Collecting regular statistics from
pg_stat*
views
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Finding what makes SQL slow
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Reducing the number of rows returned
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Simplifying complex SQL
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Speeding up queries without rewriting them
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Why queries do not use an index
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How do force a query to use an index
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Using optimistic locking
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Reporting performance problems
Introduction
Performance and concurrency are two problems that are often tightly coupled—when
concurrency grows, performance usually degrades, in some cases a lot. And, if you take care
of performance problems, you can achieve better concurrency.
In this chapter, we show you how to find slow queries, and also how to find queries that make
other queries slow.
