Postgresql分布式插件plproxy的使用详解
Simple remote function call
节点61/62(datanode)
CREATE TABLE users (username text, email text);
insert into users values ('user0', 'user0@gmail.com');
insert into users values ('user1', 'user1@gmail.com');
insert into users values ('user2', 'user2@gmail.com');
节点60(proxy)
create or replace extension plproxy;
CREATE FUNCTION get_user_email(i_username text)
RETURNS SETOF text AS $$
CONNECT 'host=localhost port=9461 dbname=postgres connect_timeout=10';
SELECT email FROM users WHERE username = $1;
$$ LANGUAGE plproxy;
SELECT * from get_user_email('user0');
Configuring Pl/Proxy clusters with SQL/MED
节点60(proxy)
CREATE FOREIGN DATA WRAPPER plproxy; CREATE SERVER usercluster FOREIGN DATA WRAPPER plproxy OPTIONS (connection_lifetime '1800', p0 'host=localhost port=9461 dbname=postgres connect_timeout=10', p1 'host=localhost port=9462 dbname=postgres connect_timeout=10' ); CREATE USER MAPPING FOR PUBLIC SERVER usercluster;
Partitioned remote call
节点60(proxy)
CREATE OR REPLACE FUNCTION insert_user(i_username text, i_emailaddress text) RETURNS integer AS $$ CLUSTER 'usercluster'; RUN ON hashtext(i_username); $$ LANGUAGE plproxy;
节点61/62(datanode)
CREATE OR REPLACE FUNCTION insert_user(i_username text, i_emailaddress text) RETURNS integer AS $$ INSERT INTO users (username, email) VALUES ($1,$2); SELECT 1; $$ LANGUAGE SQL;
Putting it all together
节点60(proxy)
SELECT insert_user('Sven','sven@somewhere.com');
SELECT insert_user('Marko', 'marko@somewhere.com');
SELECT insert_user('Steve','steve@somewhere.cm');
plproxy–2.7.0.sql
-- handler function CREATE FUNCTION plproxy_call_handler () RETURNS language_handler AS 'plproxy' LANGUAGE C; -- validator function CREATE FUNCTION plproxy_validator (oid) RETURNS void AS 'plproxy' LANGUAGE C; -- language CREATE LANGUAGE plproxy HANDLER plproxy_call_handler VALIDATOR plproxy_validator; -- validator function CREATE FUNCTION plproxy_fdw_validator (text[], oid) RETURNS boolean AS 'plproxy' LANGUAGE C; -- foreign data wrapper CREATE FOREIGN DATA WRAPPER plproxy VALIDATOR plproxy_fdw_validator;
补充：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。
以上为个人经验，希望能给大家一个参考，也希望大家多多支持潘少俊衡。如有错误或未考虑完全的地方，望不吝赐教。
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