29th September 2022: PostgreSQL 15 RC 1 Released!
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Development Versions: 15 / devel
Unsupported versions: 9.6 / 9.5 / 9.4 / 9.3 / 9.2 / 9.1 / 9.0 / 8.4 / 8.3 / 8.2 / 8.1 / 8.0 / 7.4
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Part VII. Internals

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

Table of Contents

52. Overview of PostgreSQL Internals
52.1. The Path of a Query
52.2. How Connections Are Established
52.3. The Parser Stage
52.4. The PostgreSQL Rule System
52.5. Planner/Optimizer
52.6. Executor
53. System Catalogs
53.1. Overview
53.2. pg_aggregate
53.3. pg_am
53.4. pg_amop
53.5. pg_amproc
53.6. pg_attrdef
53.7. pg_attribute
53.8. pg_authid
53.9. pg_auth_members
53.10. pg_cast
53.11. pg_class
53.12. pg_collation
53.13. pg_constraint
53.14. pg_conversion
53.15. pg_database
53.16. pg_db_role_setting
53.17. pg_default_acl
53.18. pg_depend
53.19. pg_description
53.20. pg_enum
53.21. pg_event_trigger
53.22. pg_extension
53.23. pg_foreign_data_wrapper
53.24. pg_foreign_server
53.25. pg_foreign_table
53.26. pg_index
53.27. pg_inherits
53.28. pg_init_privs
53.29. pg_language
53.30. pg_largeobject
53.31. pg_largeobject_metadata
53.32. pg_namespace
53.33. pg_opclass
53.34. pg_operator
53.35. pg_opfamily
53.36. pg_parameter_acl
53.37. pg_partitioned_table
53.38. pg_policy
53.39. pg_proc
53.40. pg_publication
53.41. pg_publication_namespace
53.42. pg_publication_rel
53.43. pg_range
53.44. pg_replication_origin
53.45. pg_rewrite
53.46. pg_seclabel
53.47. pg_sequence
53.48. pg_shdepend
53.49. pg_shdescription
53.50. pg_shseclabel
53.51. pg_statistic
53.52. pg_statistic_ext
53.53. pg_statistic_ext_data
53.54. pg_subscription
53.55. pg_subscription_rel
53.56. pg_tablespace
53.57. pg_transform
53.58. pg_trigger
53.59. pg_ts_config
53.60. pg_ts_config_map
53.61. pg_ts_dict
53.62. pg_ts_parser
53.63. pg_ts_template
53.64. pg_type
53.65. pg_user_mapping
54. System Views
54.1. Overview
54.2. pg_available_extensions
54.3. pg_available_extension_versions
54.4. pg_backend_memory_contexts
54.5. pg_config
54.6. pg_cursors
54.7. pg_file_settings
54.8. pg_group
54.9. pg_hba_file_rules
54.10. pg_ident_file_mappings
54.11. pg_indexes
54.12. pg_locks
54.13. pg_matviews
54.14. pg_policies
54.15. pg_prepared_statements
54.16. pg_prepared_xacts
54.17. pg_publication_tables
54.18. pg_replication_origin_status
54.19. pg_replication_slots
54.20. pg_roles
54.21. pg_rules
54.22. pg_seclabels
54.23. pg_sequences
54.24. pg_settings
54.25. pg_shadow
54.26. pg_shmem_allocations
54.27. pg_stats
54.28. pg_stats_ext
54.29. pg_stats_ext_exprs
54.30. pg_tables
54.31. pg_timezone_abbrevs
54.32. pg_timezone_names
54.33. pg_user
54.34. pg_user_mappings
54.35. pg_views
55. Frontend/Backend Protocol
55.1. Overview
55.2. Message Flow
55.3. SASL Authentication
55.4. Streaming Replication Protocol
55.5. Logical Streaming Replication Protocol
55.6. Message Data Types
55.7. Message Formats
55.8. Error and Notice Message Fields
55.9. Logical Replication Message Formats
55.10. Summary of Changes since Protocol 2.0
56. PostgreSQL Coding Conventions
56.1. Formatting
56.2. Reporting Errors Within the Server
56.3. Error Message Style Guide
56.4. Miscellaneous Coding Conventions
57. Native Language Support
57.1. For the Translator
57.2. For the Programmer
58. Writing a Procedural Language Handler
59. Writing a Foreign Data Wrapper
59.1. Foreign Data Wrapper Functions
59.2. Foreign Data Wrapper Callback Routines
59.3. Foreign Data Wrapper Helper Functions
59.4. Foreign Data Wrapper Query Planning
59.5. Row Locking in Foreign Data Wrappers
60. Writing a Table Sampling Method
60.1. Sampling Method Support Functions
61. Writing a Custom Scan Provider
61.1. Creating Custom Scan Paths
61.2. Creating Custom Scan Plans
61.3. Executing Custom Scans
62. Genetic Query Optimizer
62.1. Query Handling as a Complex Optimization Problem
62.2. Genetic Algorithms
62.3. Genetic Query Optimization (GEQO) in PostgreSQL
62.4. Further Reading
63. Table Access Method Interface Definition
64. Index Access Method Interface Definition
64.1. Basic API Structure for Indexes
64.2. Index Access Method Functions
64.3. Index Scanning
64.4. Index Locking Considerations
64.5. Index Uniqueness Checks
64.6. Index Cost Estimation Functions
65. Generic WAL Records
66. Custom WAL Resource Managers
67. B-Tree Indexes
67.1. Introduction
67.2. Behavior of B-Tree Operator Classes
67.3. B-Tree Support Functions
67.4. Implementation
68. GiST Indexes
68.1. Introduction
68.2. Built-in Operator Classes
68.3. Extensibility
68.4. Implementation
68.5. Examples
69. SP-GiST Indexes
69.1. Introduction
69.2. Built-in Operator Classes
69.3. Extensibility
69.4. Implementation
69.5. Examples
70. GIN Indexes
70.1. Introduction
70.2. Built-in Operator Classes
70.3. Extensibility
70.4. Implementation
70.5. GIN Tips and Tricks
70.6. Limitations
70.7. Examples
71. BRIN Indexes
71.1. Introduction
71.2. Built-in Operator Classes
71.3. Extensibility
72. Hash Indexes
72.1. Overview
72.2. Implementation
73. Database Physical Storage
73.1. Database File Layout
73.2. TOAST
73.3. Free Space Map
73.4. Visibility Map
73.5. The Initialization Fork
73.6. Database Page Layout
73.7. Heap-Only Tuples (HOT)
74. System Catalog Declarations and Initial Contents
74.1. System Catalog Declaration Rules
74.2. System Catalog Initial Data
74.3. BKI File Format
74.4. BKI Commands
74.5. Structure of the Bootstrap BKI File
74.6. BKI Example
75. How the Planner Uses Statistics
75.1. Row Estimation Examples
75.2. Multivariate Statistics Examples
75.3. Planner Statistics and Security
76. Backup Manifest Format
76.1. Backup Manifest Top-level Object
76.2. Backup Manifest File Object
76.3. Backup Manifest WAL Range Object