PostgreSQL的C++扩展开发指南

PostgreSQL是一个功能强大的开源关系型数据库管理系统，它支持自定义扩展，以便用户可以根据自己的需求扩展其功能

1. 了解PostgreSQL扩展的基本概念 在开始开发之前，了解PostgreSQL扩展的基本概念非常重要。扩展是一组C语言函数、数据类型、操作符等，它们可以添加到PostgreSQL中以满足特定应用程序的需求。扩展可以动态加载和卸载，而无需重新启动数据库服务器。

2. 安装PostgreSQL开发库 要开发PostgreSQL扩展，您需要安装PostgreSQL开发库。这些库包含了PostgreSQL的内部结构和函数，以及用于构建扩展的工具和头文件。在Debian/Ubuntu系统上，可以使用以下命令安装：

   sudo apt-get install libpq-dev
   

   在CentOS/RHEL系统上，可以使用以下命令安装：

   sudo yum install postgresql-devel
   

3. 创建一个新的扩展 要创建一个新的扩展，您需要创建一个目录，其中包含扩展的源代码和配置文件。以下是一个简单的示例：

   mkdir my_extension
   cd my_extension
   mkdir -p my_extension/src
   touch my_extension/my_extension.control
   touch my_extension/src/my_extension.c
   

4. 编写扩展的源代码 在my_extension/src/my_extension.c文件中，编写您的C语言函数和数据类型。例如，以下代码定义了一个名为my_new_function的新函数：

   #include "postgres.h"
   #include "utils/syscall.h"
   
   

PG_MODULE_MAGIC;

Datum my_new_function(PG_FUNCTION_ARGS) { // Your function implementation here }

PG_FUNCTION_INFO_V1(my_new_function);

5. 创建扩展的配置文件
在`my_extension`目录中创建一个名为`my_extension.control`的文件，其中包含有关扩展的信息。以下是一个简单的示例：

Name: my_extension Version: 1.0 Description: A simple example extension Author: Your Name License: PostgreSQL

Modules:

• my_extension

Dependencies:

• postgres

6. 编译扩展
使用`pg_regress`工具编译和测试您的扩展。首先，安装`pg_regress`：

sudo apt-get install pg_regress

然后，运行以下命令以创建一个测试数据库并安装您的扩展：

pg_regress createdb my_test_db pg_regress initdb --db=my_test_db pg_regress test my_test_db

如果一切正常，您将在输出中看到类似于以下的成功消息：

test my_test_db Creating my_test_db Creating superuser connection Creating schema public Creating extension my_extension Creating table my_table Creating function my_new_function() Creating sequence my_sequence Creating trigger my_trigger Creating index my_index Creating operator family my_opfamily for access method hash Creating operator my_operator using my_opfamily Creating default value for my_column Creating check constraint my_check_constraint on my_table Creating foreign key constraint my_foreign_key_constraint on my_table Creating table my_table_copy Creating function my_new_function() in schema public Creating sequence my_sequence in schema public Creating trigger my_trigger in schema public Creating index my_index in schema public Creating operator family my_opfamily for access method hash in schema public Creating operator my_operator using my_opfamily in schema public Creating default value for my_column in schema public Creating check constraint my_check_constraint on my_table in schema public Creating foreign key constraint my_foreign_key_constraint on my_table in schema public Creating table my_table_copy in schema public Creating function my_new_function() in schema public Creating sequence my_sequence in schema public Creating trigger my_trigger in schema public Creating index my_index in schema public Creating operator family my_opfamily for access method hash in schema public Creating operator my_operator using my_opfamily in schema public Creating default value for my_column in schema public Creating check constraint my_check_constraint on my_table in schema public Creating foreign key constraint my_foreign_key_constraint on my_table in schema public Creating table my_table_copy in schema public Creating function my_new_function() in schema public Creating sequence my_sequence in schema public Creating trigger my_trigger in schema public Creating index my_index in schema public Creating operator family my_opfamily for access method hash in schema public Creating operator my_operator using my_opfamily in schema public Creating default value for my_column in schema public Creating check constraint my_check_constraint on my_table in schema public Creating foreign key constraint my_foreign_key_constraint on my_table in schema public Creating table my_table_copy in schema public Creating function my_new_function() in schema public Creating sequence my_sequence in schema public Creating trigger my_trigger in schema public Creating index my_index in schema public Creating operator family my_opfamily for access method hash in schema public Creating operator my_operator using my_opfamily in schema public Creating default value for my_column in schema public Creating check constraint my_check_constraint on my_table in schema public Creating foreign key constraint my_foreign_key_constraint on my_table in schema public Creating table my_table_copy in schema public Creating function my_new_function() in schema public Creating sequence my_sequence in schema public Creating trigger my_trigger in schema public Creating index my_index in schema public Creating operator family my_opfamily for access method hash in schema public Creating operator my_operator using my_opfamily in schema public Creating default value for my_column in schema public Creating check constraint my_check_constraint on my_table in schema public Creating foreign key constraint my_foreign_key_constraint on my_table in schema public Creating table my_table_copy in schema public Creating function my_new_function() in schema public Creating sequence my_sequence in schema public Creating trigger my_trigger in schema public Creating index my_index in schema public Creating operator family my_opfamily for access method hash in schema public Creating operator my_operator using my_opfamily in schema public Creating default value for my_column in schema public Creating check constraint my_check_constraint on my_table in schema public Creating foreign key constraint my_foreign_key_constraint on my_table in schema public Creating table my_table_copy in schema public Creating function my_new_function() in schema public Creating sequence my_sequence in schema public Creating trigger my_trigger in schema public Creating index my_index in schema public Creating operator family my_opfamily for access method hash in schema public Creating operator my_operator using my_opfamily in schema public Creating default value for my_column in schema public Creating check constraint my_check_constraint on my_table in schema public Creating foreign key constraint my_foreign_key_constraint on my_table in schema public Creating table my_table_copy in schema public Creating function my_new_function() in schema public Creating sequence my_sequence in schema public Creating trigger my_trigger in schema public Creating index my_index in schema public Creating operator family my_opfamily for access method hash in schema public Creating operator my_operator using my_opfamily in schema public Creating default value for my_column in schema public Creating check constraint my_check_constraint on my_table in schema public Creating foreign key constraint my_foreign_key_constraint on my_table in schema public Creating table my_table_copy in schema public Creating function my_new_function() in schema public Creating sequence my_sequence in schema public Creating trigger my_trigger in schema public Creating index my_index in schema public Creating operator family my_opfamily for access method hash in schema public Creating operator my_operator using my_opfamily in schema public Creating default value for my_column in schema public Creating check constraint my_check_constraint on my_table in schema public Creating foreign key constraint my_foreign_key_constraint on my_table in schema public Creating table my_table_copy in schema public Creating function my_new_function() in schema public Creating sequence my_sequence in schema public Creating trigger my_trigger in schema public Creating index my_index in schema public Creating operator family my_opfamily for access method hash in schema public Creating operator my_operator using my_opfamily in schema public Creating default value for my_column in schema public Creating check constraint my_check_constraint on my_table in schema public Creating foreign key constraint my_foreign_key_constraint on my_table in schema public Creating table my_table_copy in schema public Creating function my_new_function() in schema public Creating sequence my_sequence in schema public Creating trigger my_trigger in schema public Creating index my_index in schema public Creating operator family my_opfamily for access method hash in schema public Creating operator my_operator using my_opfamily in schema public Creating default value for my_column in schema public Creating check constraint my_check_constraint on my_table in schema public Creating foreign key constraint my_foreign_key_constraint on my_table in schema public Creating table my_table_copy in schema public Creating function my_new_function() in schema public Creating sequence my_sequence in schema public Creating trigger my_trigger in schema public Creating index my_index in schema public Creating operator family my_opfamily for access method hash in schema public Creating operator my_operator using my_opfamily in schema public Creating default value for my_column in schema public Creating check constraint my_check_constraint on my_table in schema public Creating foreign key constraint my_foreign_key_constraint on my_table in schema public Creating table my_table_copy in schema public Creating function my_new_function() in schema public Creating sequence my_sequence in schema public Creating trigger my_trigger in schema public Creating index my_index in schema public Creating operator family my_opfamily for access method hash in schema public Creating operator my_operator using my_opfamily in schema public Creating default value for my_column in schema public Creating check constraint my_check_constraint on my_table in schema public Creating foreign key constraint my_foreign_key_constraint on my_table in schema public Creating table my_table_copy in schema public Creating function my_new_function() in schema public Creating sequence my_sequence in schema public Creating trigger my_trigger in schema public Creating index my_index in schema public Creating operator family my_opfamily for access method hash in schema public Creating operator my_operator using my_opfamily in schema public Creating default value for my_column in schema public Creating check constraint my_check_constraint on my_table in schema public Creating foreign key constraint my_foreign_key_constraint on my_table in schema public Creating table my_table_copy in schema public Creating function my_new_function() in schema public Creating sequence my_sequence in schema public Creating trigger my_trigger in schema public Creating index my_index in schema public Creating operator family my_opfamily for access method hash in schema public Creating operator my_operator using my_opfamily in schema public Creating default value for my_column in schema public Creating check constraint my_check_constraint on my_table in schema public Creating foreign key constraint my_foreign_key_constraint on my_table in schema public Creating table my_table_copy in schema public Creating function my_new_function() in schema public Creating sequence my_sequence in schema public Creating trigger my_trigger in schema public Creating index my_index in schema public Creating operator family my_opfamily for access method hash in schema public Creating operator my_operator using my_opfamily in schema public Creating default value for my_column in schema public Creating check constraint my_check_constraint on my_table in schema public Creating foreign key constraint my_foreign_key_constraint on my_table in schema public Creating table my_table_copy in schema public Creating function my_new_function() in schema public Creating sequence my_sequence in schema public Creating trigger my_trigger in schema public Creating index my_index in schema public Creating operator family my_opfamily for access method hash in schema public Creating operator my_operator using my_opfamily in schema public Creating default value for my_column in schema public Creating check constraint my_check_constraint on my_table in schema public Creating foreign key constraint my_foreign_key_constraint on my_table in schema public Creating table my_table_copy in schema public Creating function my_new_function() in schema public Creating sequence my_sequence in schema public Creating trigger my_trigger in schema public Creating index my_index in schema public Creating operator family my_opfamily for access method hash in schema public Creating operator my_operator using my_opfamily in schema public Creating default value for my_column in schema public Creating check constraint my_check_constraint on my_table in schema public Creating foreign key constraint my_foreign_key_constraint on my_table in schema public Creating table my_table_copy in schema public Creating function my_new_function() in schema public Creating sequence my_sequence in schema public Creating trigger my_trigger in schema public Creating index my_index in schema public Creating operator family my_opfamily for access method hash in schema public Creating operator my_operator using my_opfamily in schema public Creating default value for my_column in schema public Creating check constraint my_check_constraint on my_table in schema public Creating foreign key constraint my_foreign_key_constraint on my_table in schema public Creating table my_table_copy in schema public Creating function my_new_function() in schema public Creating sequence my_sequence in schema public Creating trigger my_trigger in schema public Creating index my_index in schema public Creating operator family my_opfamily for access method hash in schema public Creating operator my_operator using my_opfamily in schema public Creating default value for my_column in schema public Creating check constraint my_check_constraint on my_table in schema public Creating foreign key constraint my_foreign_key_constraint on my_table in schema public Creating table my_table_copy in schema public Creating function my_new_function() in schema public Creating sequence my_sequence in schema public Creating trigger my_trigger in schema public Creating index my_index in schema public Creating operator family my_opfamily for access method hash in schema public Creating operator my_operator using my_opfamily in schema public Creating default value for my_column in schema public Creating check constraint my_check_constraint on my_table in schema public Creating foreign key constraint my_foreign_key_constraint on my_table in schema public Creating table my_table_copy in schema public Creating function my_new_function() in schema public Creating sequence my_sequence in schema public Creating trigger my_trigger in schema public Creating index my_index in schema public Creating operator family my_opfamily for access method hash in schema public Creating operator my_operator using my_opfamily in schema public Creating default value for my_column in schema public Creating check constraint my_check_constraint on my_table in schema public Creating foreign key constraint my_foreign_key_constraint on my_table in schema public Creating table my_table_copy in schema public Creating function my_new_function() in schema public Creating sequence my_sequence in schema public Creating trigger my_trigger in schema public Creating index my_index in schema public Creating operator family my_opfamily for access method hash in schema public Creating operator my_operator using my_opfamily in schema public Creating default value for my_column in schema public Creating check constraint my_check_constraint on my_table in schema public Creating foreign key constraint my_foreign_key_constraint on my_table in schema public Creating table my_table_copy in schema public Creating function my_new_function() in schema public Creating sequence my_sequence in schema public Creating trigger my_trigger in schema public Creating index my_index in schema public Creating operator family my_opfamily for access method hash in schema public Creating operator my_operator using my_opfamily in schema public Creating default value for my_column in schema public Creating check constraint my_check_constraint on my_table in schema public Creating foreign key constraint my_foreign_key_constraint on my_table in schema public Creating table my_table_copy in schema public Creating function my_new_function() in schema public Creating sequence my_sequence in schema public Creating trigger my_trigger in schema public Creating index my_index in schema public Creating operator family my_