PostgreSQL 水平分库——plproxy

1、PL/Proxy安装
1、1 编译安装
tar -zxvf plproxy-2.7.tar.gz
cd plproxy-2.7
source /home/postgres/.bashrc
make
make install

1、2 创建pl/proxy扩展

itm_pg@pgs-> psql
psql (10.3)
Type "help" for help.

postgres=# create database proxy;
CREATE DATABASE
postgres=# \c proxy 
You are now connected to database "proxy" as user "postgres".
proxy=# create extension plproxy;
CREATE EXTENSION
proxy=# \dx
                               List of installed extensions
  Name   | Version |   Schema   |                       Description             
           
---------+---------+------------+-----------------------------------------------
-----------
 plpgsql | 1.0     | pg_catalog | PL/pgSQL procedural language
 plproxy | 2.8.0   | public     | Database partitioning implemented as procedura
l language
(2 rows)

2、pl/proxy配置
修改数据库节点pg_hba.conf:
修改两个数据节点的pg_hba.conf，保证代理节点可以访问。

# TYPE  DATABASE        USER            ADDRESS                 METHOD
  host  all             all             192.168.7.177/32         trust

在SQL/MED方法在pl/proxy节点进行集群配置：

proxy=# create schema plproxy; --下面的函数都是创建在plproxy这个schema下面
CREATE SCHEMA
proxy=# create user bill superuser;
CREATE ROLE
--创建一个使用plproxy FDW的服务器
proxy=# CREATE SERVER cluster_srv1 FOREIGN DATA WRAPPER plproxy
proxy-#         OPTIONS (
proxy(#                  connection_lifetime '1800',
proxy(#                  disable_binary '1',
proxy(#                  p0 'dbname=pl_db0 host=192.168.7.166',
proxy(#                  p1 'dbname=pl_db1 host=192.168.17.190'
proxy(#                  );
CREATE SERVER   
proxy=# \des
           List of foreign servers
     Name     | Owner | Foreign-data wrapper 
--------------+-------+----------------------
 cluster_srv1 | bill | plproxy
(1 row)

proxy=# grant usage on FOREIGN server cluster_srv1 to bill;  
GRANT
--创建用户映射
proxy=# create user mapping for bill server cluster_srv1 options (user 'bill');
CREATE USER MAPPING
proxy=# \deu
  List of user mappings
    Server    | User name 
--------------+-----------
 cluster_srv1 | bill
(1 row)

配置完成！在"CLUSTER"模式中；才需要上述配置；在"CONNECT"模式中是不需要的。

3、pl/proxy测试
在两个数据节点创建测试表：

postgres=# create database pl_db1;
CREATE DATABASE
postgres=# create user bill superuser;
CREATE ROLE
postgres=# \c pl_db1 bill 
You are now connected to database "pl_db1" as user "bill".
pl_db1=# create table users(userid int, name text);
CREATE TABLE

3、1数据水平拆分测试
在每个数据节点创建insert函数接口

pl_db1=# CREATE OR REPLACE FUNCTION insert_user(i_id int, i_name text)
pl_db1-#  RETURNS integer AS $$
pl_db1$#        INSERT INTO users (userid, name) VALUES ($1,$2);
pl_db1$#        SELECT 1;
pl_db1$#  $$ LANGUAGE SQL;
CREATE FUNCTION

–pl_db0节点一样
2、在PL/Proxy数据库创建同名的insert函数接口

proxy=#  CREATE OR REPLACE FUNCTION insert_user(i_id int, i_name text)
proxy-# RETURNS integer AS $$
proxy$#      CLUSTER 'cluster_srv1';
proxy$#     RUN ON ANY;
proxy$#  $$ LANGUAGE plproxy;
CREATE FUNCTION

3、在PL/Proxy数据库创建读的函数get_user_name()

proxy=# CREATE OR REPLACE FUNCTION get_user_name()
proxy-# RETURNS TABLE(userid int, name text) AS $$
proxy$#     CLUSTER 'cluster_srv1';
proxy$#     RUN ON ALL ;
proxy$# SELECT userid,name FROM users;
proxy$# $$ LANGUAGE plproxy;
CREATE FUNCTION

4、在pl/proxy节点插入数据进行测试

SELECT insert_user(1001, 'Sven');
SELECT insert_user(1002, 'Marko');
SELECT insert_user(1003, 'Steve');
SELECT insert_user(1004, 'bill');
SELECT insert_user(1005, 'rax');
SELECT insert_user(1006, 'ak');
SELECT insert_user(1007, 'jack');
SELECT insert_user(1008, 'molica');
SELECT insert_user(1009, 'pg');
SELECT insert_user(1010, 'oracle');

5、在节点数据库查看数据分布情况
pl_db1=# select * from users;

 userid | name  
--------+-------
   1001 | Sven
   1003 | Steve
   1004 | bill
(3 rows)

我们在proxy节点查询下：

proxy=# SELECT USERID,NAME FROM GET_USER_NAME();
 userid |  name  
--------+--------
   1005 | rax
   1006 | ak
   1008 | molica
   1009 | pg
   1002 | Marko
   1004 | bill
   1007 | jack
   1010 | oracle
   1001 | Sven
   1003 | Steve
(10 rows)

因为创建insert_user函数时使用的是ROW ON ANY，表示随机再一台机器上进行执行，因此实现了数据在不同节点的随机分布，接下来改成ROW ON ALL，实验在不同节点进行数据的复制。
run on , 是数字常量, 范围是0 到 nodes-1; 例如有4个节点 run on 0; (run on 4则报错).
run on ANY,
run on function(…), 这里用到的函数返回结果必须是int2, int4 或 int8.
run on ALL, 这种的plproxy函数必须是returns setof…, 实体函数没有setof的要求.

3、2数据复制测试
选择users表作为实验对象；我们先清理表users数据;在数据节点创建truncatet函数接口

pl_db1=#  CREATE OR REPLACE FUNCTION trunc_user()
pl_db1-# RETURNS integer AS $$
pl_db1$#        truncate table users;
pl_db1$#       SELECT 1;
pl_db1$#  $$ LANGUAGE SQL;
CREATE FUNCTION

2、在PL/Proxy数据库创建同名的truncate函数接口

proxy=#  CREATE OR REPLACE FUNCTION trunc_user()
proxy-#  RETURNS SETOF integer AS $$
proxy$#       CLUSTER 'cluster_srv1';
proxy$#       RUN ON ALL;
proxy$#   $$ LANGUAGE plproxy;
CREATE FUNCTION

–检查发现数据已经清理掉了

proxy=# SELECT TRUNC_USER();
 trunc_user 
------------
          1
          1
(2 rows)

3、在PL/Proxy数据库创建函数接口 insert_user_2

proxy=# CREATE OR REPLACE FUNCTION insert_user_2(i_id int, i_name text)
proxy-#    RETURNS SETOF integer AS $$
proxy$#        CLUSTER 'cluster_srv1';
proxy$#        RUN ON ALL;
proxy$#    TARGET insert_user;
proxy$#    $$ LANGUAGE plproxy;
CREATE FUNCTION

4、插入几条数据

proxy=# SELECT insert_user_2(1004, 'bill');
 insert_user_2 
---------------
             1
             1
(2 rows)

proxy=# SELECT insert_user_2(1005, 'rax');
 insert_user_2 
---------------
             1
             1
(2 rows)

proxy=# SELECT insert_user_2(1006, 'ak');
 insert_user_2 
---------------
             1
             1
(2 rows)

proxy=# SELECT insert_user_2(1007, 'jack');
 insert_user_2 
---------------
             1
             1
(2 rows)

5、查看每个节点数据情况

pl_db1=# select * from users;
 userid | name  
--------+-------
   1004 | bill
   1005 | rax
   1006 | ak
   1007 | jack
(4 rows)
pl_db0=# select * from users;
 userid | name  
--------+-------
   1004 | bill
   1005 | rax
   1006 | ak
   1007 | jack
(4 rows)

两个数据节点的数据一样，实现了数据的复制。