November 13, 2025: PostgreSQL 18.1, 17.7, 16.11, 15.15, 14.20, and 13.23 Released!
Supported Versions: Current (18) / 17 / 16 / 15 / 14
Development Versions: devel
Unsupported versions: 13 / 12 / 11 / 10 / 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 / 7.3 / 7.2 / 7.1
Chapter 38. Extending SQL
Prev  Up Part V. Server Programming Home  Next

Chapter 38. Extending SQL

Table of Contents

38.1. How Extensibility Works
38.2. The PostgreSQL Type System
38.2.1. Base Types
38.2.2. Container Types
38.2.3. Domains
38.2.4. Pseudo-Types
38.2.5. Polymorphic Types
38.3. User-Defined Functions
38.4. User-Defined Procedures
38.5. Query Language (SQL) Functions
38.5.1. Arguments for SQL Functions
38.5.2. SQL Functions on Base Types
38.5.3. SQL Functions on Composite Types
38.5.4. SQL Functions with Output Parameters
38.5.5. SQL Procedures with Output Parameters
38.5.6. SQL Functions with Variable Numbers of Arguments
38.5.7. SQL Functions with Default Values for Arguments
38.5.8. SQL Functions as Table Sources
38.5.9. SQL Functions Returning Sets
38.5.10. SQL Functions Returning TABLE
38.5.11. Polymorphic SQL Functions
38.5.12. SQL Functions with Collations
38.6. Function Overloading
38.7. Function Volatility Categories
38.8. Procedural Language Functions
38.9. Internal Functions
38.10. C-Language Functions
38.10.1. Dynamic Loading
38.10.2. Base Types in C-Language Functions
38.10.3. Version 1 Calling Conventions
38.10.4. Writing Code
38.10.5. Compiling and Linking Dynamically-Loaded Functions
38.10.6. Composite-Type Arguments
38.10.7. Returning Rows (Composite Types)
38.10.8. Returning Sets
38.10.9. Polymorphic Arguments and Return Types
38.10.10. Shared Memory and LWLocks
38.10.11. Using C++ for Extensibility
38.11. Function Optimization Information
38.12. User-Defined Aggregates
38.12.1. Moving-Aggregate Mode
38.12.2. Polymorphic and Variadic Aggregates
38.12.3. Ordered-Set Aggregates
38.12.4. Partial Aggregation
38.12.5. Support Functions for Aggregates
38.13. User-Defined Types
38.13.1. TOAST Considerations
38.14. User-Defined Operators
38.15. Operator Optimization Information
38.15.1. COMMUTATOR
38.15.2. NEGATOR
38.15.3. RESTRICT
38.15.4. JOIN
38.15.5. HASHES
38.15.6. MERGES
38.16. Interfacing Extensions to Indexes
38.16.1. Index Methods and Operator Classes
38.16.2. Index Method Strategies
38.16.3. Index Method Support Routines