原 为PostgreSQL添加插件
时间:2022-05-16
本文章向大家介绍原 为PostgreSQL添加插件，主要内容包括其使用实例、应用技巧、基本知识点总结和需要注意事项，具有一定的参考价值，需要的朋友可以参考一下。
我目前了解的PG插件大约有两种，一种是利用hook，另一种是建立C函数，然后在数据库中进行关联。PG本身就是最好的老师，大家有兴趣可以看一下contrib目录下的插件。
下面将对两种方式进行介绍：
1、利用hook建立插件，hook是PG中可以对PG运行机制进行修改的一种方式，大家可以看一下我之前对PG hook的介绍：
a.在contrib目录下建立brother目录，建立brother.c文件和Makefile文件。具体内容见下：
brother.c（在用户brother登录验证成功后，显示信息Welcome to the world of PostgreSQL!）:
/*-------------------------------------------------------------------------
*
* brother.c
* welcome to the world of PostgreSQL
*
* contrib/brother/brother.c
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "libpq/auth.h"
#include "miscadmin.h"
#include "utils/guc.h"
PG_MODULE_MAGIC;
void _PG_init(void);
void _PG_fini(void);
static ClientAuthentication_hook_type pre_ClientAuthentication_hook = NULL;
static
void welcome_to_pg(Port *port, int status)
{
if(status == STATUS_OK && (strcmp(port->user_name, "brother") == 0))
printf("Welcome to the world of PostgreSQL!n");
}
void
_PG_init(void)
{
pre_ClientAuthentication_hook = ClientAuthentication_hook;
ClientAuthentication_hook = welcome_to_pg;
}
void
_PG_fini(void)
{
ClientAuthentication_hook = pre_ClientAuthentication_hook;
}Makefile文件：
# contrib/brother/Makefile
MODULE_big = brother
OBJS = brother.o
# uncomment the following two lines to enable cracklib support
# PG_CPPFLAGS = -DUSE_CRACKLIB '-DCRACKLIB_DICTPATH="/usr/lib/cracklib_dict"'
# SHLIB_LINK = -lcrack
ifdef USE_PGXS
PG_CONFIG = pg_config
PGXS := $(shell $(PG_CONFIG) --pgxs)
include $(PGXS)
else
subdir = contrib/brother
top_builddir = ../..
include $(top_builddir)/src/Makefile.global
include $(top_srcdir)/contrib/contrib-global.mk
endifb.编译并安装
[postgres@localhost brother]$ make
gcc -Wall -Wmissing-prototypes -Wpointer-arith -Wdeclaration-after-statement -Wendif-labels -Wmissing-format-attribute -Wformat-security -fno-strict-aliasing -fwrapv -g -O2 -fpic -I. -I. -I../../src/include -D_GNU_SOURCE -c -o brother.o brother.c
gcc -Wall -Wmissing-prototypes -Wpointer-arith -Wdeclaration-after-statement -Wendif-labels -Wmissing-format-attribute -Wformat-security -fno-strict-aliasing -fwrapv -g -O2 -fpic -shared -o brother.so brother.o -L../../src/port -L../../src/common -Wl,--as-needed -Wl,-rpath,'/opt/hg3.0/lib',--enable-new-dtags
[postgres@localhost brother]$ make install
/bin/mkdir -p '/opt/hg3.0/lib/postgresql'
/usr/bin/install -c -m 755 brother.so '/opt/hg3.0/lib/postgresql/brother.so'c.文件安装位置
[postgres@localhost postgresql]$ pwd
/opt/hg3.0/lib/postgresql
[postgres@localhost postgresql]$ ll brother.so
-rwxr-xr-x. 1 postgres postgres 21523 Dec 23 06:27 brother.sod.在postgresql.conf中配置
shared_preload_libraries = 'brother'e.运行，查看效果
[postgres@localhost bin]$ ./pg_ctl -D ../data start
server starting
[postgres@localhost bin]$ LOG: database system was shut down at 2015-12-23 06:32:38 PST
LOG: MultiXact member wraparound protections are now enabled
LOG: database system is ready to accept connections
LOG: autovacuum launcher started
[postgres@localhost bin]$ ./psql
psql (9.4.5)
Type "help" for help.
postgres=# create user brother;
CREATE ROLE
[postgres@localhost bin]$ ./psql postgres brother
Welcome to the world of PostgreSQL!
psql (9.4.5)
Type "help" for help.
postgres=>2、建立C函数，并建立关联
a.在contrib下建立目录userid，建立C文件userid.c，建立Makefile文件，建立两个SQL文件，userid--1.0.sql，userid--unpackaged--1.0.sql，以及一个control文件，userid.control。
(1)C文件和Makefile就不介绍了，内容如下： userid.c：
/*-------------------------------------------------------------------------
*
* userid.c
* display current session user oid
*
* contrib/userid/userid.c
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "libpq/auth.h"
#include "utils/guc.h"
#include "miscadmin.h"
PG_MODULE_MAGIC;
PG_FUNCTION_INFO_V1(get_current_user_id);
Datum
get_current_user_id(PG_FUNCTION_ARGS)
{
PG_RETURN_OID(GetSessionUserId());
}Makefile：
# contrib/userid/Makefile
MODULE_big = userid
OBJS = userid.o
EXTENSION = userid
DATA = userid--1.0.sql userid--unpackaged--1.0.sql
ifdef USE_PGXS
PG_CONFIG = pg_config
PGXS := $(shell $(PG_CONFIG) --pgxs)
include $(PGXS)
else
subdir = contrib/userid
top_builddir = ../..
include $(top_builddir)/src/Makefile.global
include $(top_srcdir)/contrib/contrib-global.mk
endif(2)userid--1.0.sql是在create extension时加载的SQL文件，会执行SQL文件中的sql，内容如下：
/* contrib/userid/userid--1.0.sql */
-- complain if script is sourced in psql, rather than via CREATE EXTENSION
echo Use "CREATE EXTENSION userid" to load this file. quit
-- Register the function.
CREATE SCHEMA brother;
CREATE FUNCTION get_current_userid()
RETURNS OID
AS 'MODULE_PATHNAME', 'get_current_user_id'
LANGUAGE C;(3) userid--unpackaged--1.0.sql是CREATE EXTENSION userid FROM unpackaged时调用的SQL文件，这个文件是在更新9.1之前版本的插件函数时使用的，后面会介绍用法。
/* contrib/userid/userid--unpackaged--1.0.sql */
-- complain if script is sourced in psql, rather than via CREATE EXTENSION
echo Use "CREATE EXTENSION userid FROM unpackaged" to load this file. quit
ALTER EXTENSION userid ADD schema brother;
ALTER EXTENSION userid ADD function get_current_userid();(4)control文件是在create extension加载的文件，根据这个文件，PG去寻找对应的sql文件，内容如下：
# userid extension
comment = 'display current session user oid'
default_version = '1.0'
module_pathname = '$libdir/userid'
relocatable = trueb.编译安装
[postgres@localhost userid]$ make
gcc -Wall -Wmissing-prototypes -Wpointer-arith -Wdeclaration-after-statement -Wendif-labels -Wmissing-format-attribute -Wformat-security -fno-strict-aliasing -fwrapv -g -O2 -fpic -I. -I. -I../../src/include -D_GNU_SOURCE -c -o userid.o userid.c
gcc -Wall -Wmissing-prototypes -Wpointer-arith -Wdeclaration-after-statement -Wendif-labels -Wmissing-format-attribute -Wformat-security -fno-strict-aliasing -fwrapv -g -O2 -fpic -shared -o userid.so userid.o -L../../src/port -L../../src/common -Wl,--as-needed -Wl,-rpath,'/opt/hg3.0/lib',--enable-new-dtags
[postgres@localhost userid]$ make install
/bin/mkdir -p '/opt/hg3.0/lib/postgresql'
/bin/mkdir -p '/opt/hg3.0/share/postgresql/extension'
/bin/mkdir -p '/opt/hg3.0/share/postgresql/extension'
/usr/bin/install -c -m 755 userid.so '/opt/hg3.0/lib/postgresql/userid.so'
/usr/bin/install -c -m 644 userid.control '/opt/hg3.0/share/postgresql/extension/'
/usr/bin/install -c -m 644 userid--1.0.sql userid--unpackaged--1.0.sql '/opt/hg3.0/share/postgresql/extension/'c.文件安装位置
[postgres@localhost postgresql]$ pwd
/opt/hg3.0/lib/postgresql
[postgres@localhost postgresql]$ ll userid.so
-rwxr-xr-x. 1 postgres postgres 18665 Dec 23 06:48 userid.so
[postgres@localhost extension]$ pwd
/opt/hg3.0/share/postgresql/extension
[postgres@localhost extension]$ ll userid*
-rw-r--r--. 1 postgres postgres 329 Dec 23 06:48 userid--1.0.sql
-rw-r--r--. 1 postgres postgres 142 Dec 23 06:48 userid.control
-rw-r--r--. 1 postgres postgres 304 Dec 23 06:48 userid--unpackaged--1.0.sqld.配置
[postgres@localhost bin]$ ./psql
psql (9.4.5)
Type "help" for help.
postgres=# create extension userid;
CREATE EXTENSION
postgres=# select * from pg_extension ;
extname | extowner | extnamespace | extrelocatable | extversion | ex
tconfig | extcondition
--------------------+----------+--------------+----------------+------------+---
--------+--------------
plpgsql | 10 | 11 | f | 1.0 |
|
pgfincore | 10 | 2200 | t | 1.1.1 |
|
pg_stat_statements | 10 | 2200 | t | 1.2 |
|
pg_freespacemap | 10 | 2200 | t | 1.0 |
|
pgstattuple | 10 | 2200 | t | 1.2 |
|
userid | 10 | 2200 | t | 1.0 |
|
(6 rows)e.运行，查看效果
postgres=# select SESSION_USER;
session_user
--------------
postgres
(1 row)
postgres=# select oid from pg_authid where rolname = 'postgres';
oid
-----
10
(1 row)
postgres=# select get_current_userid();
get_current_userid
--------------------
10
(1 row)
postgres=# dn
List of schemas
Name | Owner
---------+----------
brother | postgres
public | postgres
(2 rows)
postgres=#f.使用unpackaged.sql，这里是更新9.1之前的插件使用的，现在来模拟一下：
postgres=# create schema brother;
CREATE SCHEMA
postgres=# CREATE FUNCTION get_current_userid()
RETURNS OID
AS '$libdir/userid', 'get_current_user_id'
LANGUAGE C;
CREATE FUNCTION
postgres=# create extension userid with schema public from unpackaged;
CREATE EXTENSION因为在9.1之前都是利用SQL安装的插件，没有和extension进行关联，so，在这里可以关联一下。那什么是关联呢？
g.extension关联的意思，首先大家需要知道PG的表，pg_depend。这张表是当我们进行drop时，添加参数CASCADE会调用查询的一张表，这张表主要存储对象oid依赖的对象oid等等。下面来看一下：
postgres=# select oid from pg_proc where proname = 'get_current_userid';
oid
-------
24715
(1 row)
postgres=# select oid from pg_namespace where nspname = 'brother';
oid
-------
24714
(1 row)
postgres=# select oid from pg_extension where extname = 'userid';
oid
-------
24716
(1 row)
postgres=# select * from pg_depend where refobjid = 24716;
classid | objid | objsubid | refclassid | refobjid | refobjsubid | deptype
---------+-------+----------+------------+----------+-------------+---------
2615 | 24714 | 0 | 3079 | 24716 | 0 | e
1255 | 24715 | 0 | 3079 | 24716 | 0 | e
(2 rows)这个地方就是当你drop extension时，同时会删除你插件中SQL文件建立的对象的原因。那当create extension时，又是什么地方去写pg_depend信息的呢？
h.当你进行create extension时，下面这段代码就是自动建立关联的代码：
/*
* If we are executing a CREATE EXTENSION operation, mark the given object
* as being a member of the extension. Otherwise, do nothing.
*
* This must be called during creation of any user-definable object type
* that could be a member of an extension.
*
* If isReplace is true, the object already existed (or might have already
* existed), so we must check for a pre-existing extension membership entry.
* Passing false is a guarantee that the object is newly created, and so
* could not already be a member of any extension.
*/
void
recordDependencyOnCurrentExtension(const ObjectAddress *object,
bool isReplace)
{
/* Only whole objects can be extension members */
Assert(object->objectSubId == 0);
if (creating_extension)
{
ObjectAddress extension;
/* Only need to check for existing membership if isReplace */
if (isReplace)
{
Oid oldext;
oldext = getExtensionOfObject(object->classId, object->objectId);
if (OidIsValid(oldext))
{
/* If already a member of this extension, nothing to do */
if (oldext == CurrentExtensionObject)
return;
/* Already a member of some other extension, so reject */
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("%s is already a member of extension "%s"",
getObjectDescription(object),
get_extension_name(oldext))));
}
}
/* OK, record it as a member of CurrentExtensionObject */
extension.classId = ExtensionRelationId;
extension.objectId = CurrentExtensionObject;
extension.objectSubId = 0;
recordDependencyOn(object, &extension, DEPENDENCY_EXTENSION);
}
}至此，就是我在学习PG源码中学习到的知识。这里介绍的还比较简单，请大家多多关注，我后续还会继续整理的。
- Java中Optional使用注意事项
- 使用awk来解析dump文件 (73天)
- IntelIj IDEA运行JUnit Test OutOfMemoryError
- git pull fails “unable to resolve reference” “unable to update local ref”
- 使用dropwizard(5)--加入swagger
- 使用hint来调优sql语句(72天）
- 用R语言对城管事件数据分析
- 使用dropwizard(4)-加入测试-jacoco代码覆盖率
- goldengate学习-安装篇（71天)
- 使用dropwizard(6)-国际化-easy-i18n
- 配置不同环境下启用swagger，在生产环境关闭swagger
- 使用ControllerAdvice注意事项，Ambiguous @ExceptionHandler method mapped for [class org.springframework.web.
- rac节点无法启动ORA-29702的问题及分析（70天)
- SpringMVC,SpringBoot文件下载
- JavaScript 教程
- JavaScript 编辑工具
- JavaScript 与HTML
- JavaScript 与Java
- JavaScript 数据结构
- JavaScript 基本数据类型
- JavaScript 特殊数据类型
- JavaScript 运算符
- JavaScript typeof 运算符
- JavaScript 表达式
- JavaScript 类型转换
- JavaScript 基本语法
- JavaScript 注释
- Javascript 基本处理流程
- Javascript 选择结构
- Javascript if 语句
- Javascript if 语句的嵌套
- Javascript switch 语句
- Javascript 循环结构
- Javascript 循环结构实例
- Javascript 跳转语句
- Javascript 控制语句总结
- Javascript 函数介绍
- Javascript 函数的定义
- Javascript 函数调用
- Javascript 几种特殊的函数
- JavaScript 内置函数简介
- Javascript eval() 函数
- Javascript isFinite() 函数
- Javascript isNaN() 函数
- parseInt() 与 parseFloat()
- escape() 与 unescape()
- Javascript 字符串介绍
- Javascript length属性
- javascript 字符串函数
- Javascript 日期对象简介
- Javascript 日期对象用途
- Date 对象属性和方法
- Javascript 数组是什么
- Javascript 创建数组
- Javascript 数组赋值与取值
- Javascript 数组属性和方法