This part contains assorted information that might be of use toPostgreSQL developers.

Table of Contents

47.Overview of PostgreSQL Internals

47.1.The Path of a Query

47.2.How Connections are Established

47.3.The Parser Stage

47.4.ThePostgreSQL Rule System

47.5.Planner/Optimizer

47.6.Executor

48.System Catalogs

48.1.Overview

48.2.pg_aggregate

48.3.pg_am

48.4.pg_amop

48.5.pg_amproc

48.6.pg_attrdef

48.7.pg_attribute

48.8.pg_authid

48.9.pg_auth_members

48.10.pg_cast

48.11.pg_class

48.12.pg_collation

48.13.pg_constraint

48.14.pg_conversion

48.15.pg_database

48.16.pg_db_role_setting

48.17.pg_default_acl

48.18.pg_depend

48.19.pg_description

48.20.pg_enum

48.21.pg_event_trigger

48.22.pg_extension

48.23.pg_foreign_data_wrapper

48.24.pg_foreign_server

48.25.pg_foreign_table

48.26.pg_index

48.27.pg_inherits

48.28.pg_language

48.29.pg_largeobject

48.30.pg_largeobject_metadata

48.31.pg_namespace

48.32.pg_opclass

48.33.pg_operator

48.34.pg_opfamily

48.35.pg_pltemplate

48.36.pg_proc

48.37.pg_range

48.38.pg_rewrite

48.39.pg_replication_slots

48.40.pg_seclabel

48.41.pg_shdepend

48.42.pg_shdescription

48.43.pg_shseclabel

48.44.pg_statistic

48.45.pg_tablespace

48.46.pg_trigger

48.47.pg_ts_config

48.48.pg_ts_config_map

48.49.pg_ts_dict

48.50.pg_ts_parser

48.51.pg_ts_template

48.52.pg_type

48.53.pg_user_mapping

48.54.System Views

48.55.pg_available_extensions

48.56.pg_available_extension_versions

48.57.pg_cursors

48.58.pg_group

48.59.pg_indexes

48.60.pg_locks

48.61.pg_matviews

48.62.pg_prepared_statements

48.63.pg_prepared_xacts

48.64.pg_roles

48.65.pg_rules

48.66.pg_seclabels

48.67.pg_settings

48.68.pg_shadow

48.69.pg_stats

48.70.pg_tables

48.71.pg_timezone_abbrevs

48.72.pg_timezone_names

48.73.pg_user

48.74.pg_user_mappings

48.75.pg_views

49.Frontend/Backend Protocol

49.1.Overview

49.2.Message Flow

49.3.Streaming Replication Protocol

49.4.Message Data Types

49.5.Message Formats

49.6.Error and Notice Message Fields

49.7.Summary of Changes since Protocol 2.0

50.PostgreSQL Coding Conventions

50.1.Formatting

50.2.Reporting Errors Within the Server

50.3.Error Message Style Guide

51.Native Language Support

51.1.For the Translator

51.2.For the Programmer

52.Writing A Procedural Language Handler

53.Writing A Foreign Data Wrapper

53.1.Foreign Data Wrapper Functions

53.2.Foreign Data Wrapper Callback Routines

53.3.Foreign Data Wrapper Helper Functions

53.4.Foreign Data Wrapper Query Planning

54.Genetic Query Optimizer

54.1.Query Handling as a Complex Optimization Problem

54.2.Genetic Algorithms

54.3.Genetic Query Optimization (GEQO) in PostgreSQL

54.4.Further Reading

55.Index Access Method Interface Definition

55.1.Catalog Entries for Indexes

55.2.Index Access Method Functions

55.3.Index Scanning

55.4.Index Locking Considerations

55.5.Index Uniqueness Checks

55.6.Index Cost Estimation Functions

56.GiST Indexes

56.1.Introduction

56.2.Built-in Operator Classes

56.3.Extensibility

56.4.Implementation

56.5.Examples

57.SP-GiST Indexes

57.1.Introduction

57.2.Built-in Operator Classes

57.3.Extensibility

57.4.Implementation

57.5.Examples

58.GIN Indexes

58.1.Introduction

58.2.Built-in Operator Classes

58.3.Extensibility

58.4.Implementation

58.5.GIN Tips and Tricks

58.6.Limitations

58.7.Examples

59.Database Physical Storage

59.1.Database File Layout

59.2.TOAST

59.3.Free Space Map

59.4.Visibility Map

59.5.The Initialization Fork

59.6.Database Page Layout

60.BKI Backend Interface

60.1.BKI File Format

60.2.BKI Commands

60.3.Structure of the BootstrapBKI File

60.4.Example

61.How the Planner Uses Statistics

61.1.Row Estimation Examples