PostgreSQL

Chapter 72. How the Planner Uses Statistics
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Chapter 72. How the Planner Uses Statistics

Table of Contents

72.1. Row Estimation Examples

72.2. Multivariate Statistics Examples

72.2.1. Functional Dependencies

72.2.2. Multivariate N-Distinct Counts

72.2.3. MCV Lists

72.3. Planner Statistics and Security

This chapter builds on the material covered in Section 14.1 and Section 14.2 to show some additional details about how the planner uses the system statistics to estimate the number of rows each part of a query might return. This is a significant part of the planning process, providing much of the raw material for cost calculation.

The intent of this chapter is not to document the code in detail, but to present an overview of how it works. This will perhaps ease the learning curve for someone who subsequently wishes to read the code.

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71.6. BKI Example	Home	72.1. Row Estimation Examples

71.6. BKI Example

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72.1. Row Estimation Examples

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