> For the complete documentation index, see [llms.txt](https://docs.postgresql.tw/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.postgresql.tw/server-programming/extend.md).

# Chapter 36. Extending SQL

**Table of Contents**

[36.1. How Extensibility Works](/server-programming/extend/extend-how.md)

[36.2. The PostgreSQL Type System](/server-programming/extend/extend-type-system.md) : [36.2.1. Base Types](/server-programming/extend/extend-type-system.md#EXTEND-TYPE-SYSTEM-BASE)

```
[36.2.2. Container Types](extend-type-system.md#EXTEND-TYPE-SYSTEM-CONTAINER)

[36.2.3. Domains](extend-type-system.md#EXTEND-TYPE-SYSTEM-DOMAINS)

[36.2.4. Pseudo-Types](extend-type-system.md#EXTEND-TYPE-SYSTEM-PSEUDO)

[36.2.5. Polymorphic Types](extend-type-system.md#EXTEND-TYPES-POLYMORPHIC)
```

[36.3. User-Defined Functions](/server-programming/extend/xfunc.md)

[36.4. User-Defined Procedures](/server-programming/extend/xproc.md)

[36.5. Query Language (SQL) Functions](/server-programming/extend/xfunc-sql.md) : [36.5.1. Arguments for SQL Functions](/server-programming/extend/xfunc-sql.md#XFUNC-SQL-FUNCTION-ARGUMENTS)

```
[36.5.2. SQL Functions on Base Types](xfunc-sql.md#XFUNC-SQL-BASE-FUNCTIONS)

[36.5.3. SQL Functions on Composite Types](xfunc-sql.md#XFUNC-SQL-COMPOSITE-FUNCTIONS)

[36.5.4. SQL Functions with Output Parameters](xfunc-sql.md#XFUNC-OUTPUT-PARAMETERS)

[36.5.5. SQL Procedures with Output Parameters](xfunc-sql.md#XFUNC-OUTPUT-PARAMETERS-PROC)

[36.5.6. SQL Functions with Variable Numbers of Arguments](xfunc-sql.md#XFUNC-SQL-VARIADIC-FUNCTIONS)

[36.5.7. SQL Functions with Default Values for Arguments](xfunc-sql.md#XFUNC-SQL-PARAMETER-DEFAULTS)

[36.5.8. SQL Functions as Table Sources](xfunc-sql.md#XFUNC-SQL-TABLE-FUNCTIONS)

[36.5.9. SQL Functions Returning Sets](xfunc-sql.md#XFUNC-SQL-FUNCTIONS-RETURNING-SET)

[36.5.10. SQL Functions Returning `TABLE`](xfunc-sql.md#XFUNC-SQL-FUNCTIONS-RETURNING-TABLE)

[36.5.11. Polymorphic SQL Functions](xfunc-sql.md#XFUNC-SQL-POLYMORPHIC-FUNCTIONS)

[36.5.12. SQL Functions with Collations](xfunc-sql.md#XFUNC-SQL-COLLATIONS)
```

[36.6. Function Overloading](/server-programming/extend/xfunc-overload.md)

[36.7. Function Volatility Categories](/server-programming/extend/xfunc-volatility.md)

[36.8. Procedural Language Functions](/server-programming/extend/xfunc-pl.md)

[36.9. Internal Functions](/server-programming/extend/xfunc-internal.md)

[36.10. C-Language Functions](/server-programming/extend/xfunc-c.md) : [36.10.1. Dynamic Loading](/server-programming/extend/xfunc-c.md#XFUNC-C-DYNLOAD)

```
[36.10.2. Base Types in C-Language Functions](xfunc-c.md#XFUNC-C-BASETYPE)

[36.10.3. Version 1 Calling Conventions](xfunc-c.md#XFUNC-C-V1-CALL-CONV)

[36.10.4. Writing Code](xfunc-c.md#XFUNC-C-CODE)

[36.10.5. Compiling and Linking Dynamically-Loaded Functions](xfunc-c.md#DFUNC)

[36.10.6. Server API and ABI Stability Guidance](xfunc-c.md#XFUNC-API-ABI-STABILITY-GUIDANCE)

[36.10.7. Composite-Type Arguments](xfunc-c.md#XFUNC-C-COMPOSITE-TYPE-ARGS)

[36.10.8. Returning Rows (Composite Types)](xfunc-c.md#XFUNC-C-RETURNING-ROWS)

[36.10.9. Returning Sets](xfunc-c.md#XFUNC-C-RETURN-SET)

[36.10.10. Polymorphic Arguments and Return Types](xfunc-c.md#XFUNC-C-POLYMORPHIC)

[36.10.11. Shared Memory](xfunc-c.md#XFUNC-SHARED-ADDIN)

[36.10.12. LWLocks](xfunc-c.md#XFUNC-ADDIN-LWLOCKS)

[36.10.13. Custom Wait Events](xfunc-c.md#XFUNC-ADDIN-WAIT-EVENTS)

[36.10.14. Injection Points](xfunc-c.md#XFUNC-ADDIN-INJECTION-POINTS)

[36.10.15. Custom Cumulative Statistics](xfunc-c.md#XFUNC-ADDIN-CUSTOM-CUMULATIVE-STATISTICS)

[36.10.16. Using C++ for Extensibility](xfunc-c.md#EXTEND-CPP)
```

[36.11. Function Optimization Information](/server-programming/extend/xfunc-optimization.md)

[36.12. User-Defined Aggregates](/server-programming/extend/xaggr.md) : [36.12.1. Moving-Aggregate Mode](/server-programming/extend/xaggr.md#XAGGR-MOVING-AGGREGATES)

```
[36.12.2. Polymorphic and Variadic Aggregates](xaggr.md#XAGGR-POLYMORPHIC-AGGREGATES)

[36.12.3. Ordered-Set Aggregates](xaggr.md#XAGGR-ORDERED-SET-AGGREGATES)

[36.12.4. Partial Aggregation](xaggr.md#XAGGR-PARTIAL-AGGREGATES)

[36.12.5. Support Functions for Aggregates](xaggr.md#XAGGR-SUPPORT-FUNCTIONS)
```

[36.13. User-Defined Types](/server-programming/extend/xtypes.md) : [36.13.1. TOAST Considerations](/server-programming/extend/xtypes.md#XTYPES-TOAST)

[36.14. User-Defined Operators](/server-programming/extend/xoper.md)

[36.15. Operator Optimization Information](/server-programming/extend/xoper-optimization.md) : [36.15.1. `COMMUTATOR`](/server-programming/extend/xoper-optimization.md#XOPER-COMMUTATOR)

```
[36.15.2. `NEGATOR`](xoper-optimization.md#XOPER-NEGATOR)

[36.15.3. `RESTRICT`](xoper-optimization.md#XOPER-RESTRICT)

[36.15.4. `JOIN`](xoper-optimization.md#XOPER-JOIN)

[36.15.5. `HASHES`](xoper-optimization.md#XOPER-HASHES)

[36.15.6. `MERGES`](xoper-optimization.md#XOPER-MERGES)
```

[36.16. Interfacing Extensions to Indexes](/server-programming/extend/xindex.md) : [36.16.1. Index Methods and Operator Classes](/server-programming/extend/xindex.md#XINDEX-OPCLASS)

```
[36.16.2. Index Method Strategies](xindex.md#XINDEX-STRATEGIES)

[36.16.3. Index Method Support Routines](xindex.md#XINDEX-SUPPORT)

[36.16.4. An Example](xindex.md#XINDEX-EXAMPLE)

[36.16.5. Operator Classes and Operator Families](xindex.md#XINDEX-OPFAMILY)

[36.16.6. System Dependencies on Operator Classes](xindex.md#XINDEX-OPCLASS-DEPENDENCIES)

[36.16.7. Ordering Operators](xindex.md#XINDEX-ORDERING-OPS)

[36.16.8. Special Features of Operator Classes](xindex.md#XINDEX-OPCLASS-FEATURES)
```

[36.17. Packaging Related Objects into an Extension](/server-programming/extend/extend-extensions.md) : [36.17.1. Extension Files](/server-programming/extend/extend-extensions.md#EXTEND-EXTENSIONS-FILES)

```
[36.17.2. Extension Relocatability](extend-extensions.md#EXTEND-EXTENSIONS-RELOCATION)

[36.17.3. Extension Configuration Tables](extend-extensions.md#EXTEND-EXTENSIONS-CONFIG-TABLES)

[36.17.4. Extension Updates](extend-extensions.md#EXTEND-EXTENSIONS-UPDATES)

[36.17.5. Installing Extensions Using Update Scripts](extend-extensions.md#EXTEND-EXTENSIONS-UPDATE-SCRIPTS)

[36.17.6. Security Considerations for Extensions](extend-extensions.md#EXTEND-EXTENSIONS-SECURITY)

[36.17.7. Extension Example](extend-extensions.md#EXTEND-EXTENSIONS-EXAMPLE)
```

[36.18. Extension Building Infrastructure](/server-programming/extend/extend-pgxs.md)

In the sections that follow, we will discuss how you can extend the PostgreSQL SQL query language by adding:

* functions (starting in [Section 36.3](/server-programming/extend/xfunc.md))
* aggregates (starting in [Section 36.12](/server-programming/extend/xaggr.md))
* data types (starting in [Section 36.13](/server-programming/extend/xtypes.md))
* operators (starting in [Section 36.14](/server-programming/extend/xoper.md))
* operator classes for indexes (starting in [Section 36.16](/server-programming/extend/xindex.md))
* packages of related objects (starting in [Section 36.17](/server-programming/extend/extend-extensions.md))

***

原文：[PostgreSQL 18.6 Documentation](https://www.postgresql.org/docs/18/extend.html)（英文原文，待翻譯）


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