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', '[e-mail]');
insert into users values ('user1', '[e-mail]');
insert into users values ('user2', '[e-mail]');

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','[e-mail]');
select insert_user('marko', '[e-mail]');
select insert_user('steve','[e-mail]');

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。如有错误或未考虑完全的地方，望不吝赐教。