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plproxy 2.x fast deployment

2015-10-14 22:39 597 查看

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我一直以来都比较推荐plproxy这个PostgreSQL代理软件, 因为它小巧灵活好用, 效率高.

最近朋友邀请我给他们做个分布式的方案, 所以又把plproxy翻出来了.

本文讲一讲在单节点中如何快速的部署plproxy环境.

环境 :

PostgreSQL 9.3.1plproxy 2.x
plrpoxy库 : hostaddr 172.16.3.150port 1921user proxypassword proxydbname proxyschema digoal // 这个schema名和数据节点一致, 可以省去写target的步骤.
数据节点 : hostaddr 172.16.3.150port 1921user digoal // plproxy将使用digoal用户连接数据节点.password digoal
dbname db0schema digoaldbname db1schema digoaldbname db2schema digoaldbname db3schema digoal

首先在http://git.postgresql.org/gitweb/?p=plproxy.git;a=summary下载plproxy.
安装plproxy.

tar -zxvf plproxy-d703683.tar.gzmv plproxy-d703683 /opt/soft_bak/postgresql-9.3.1/contribcd /opt/soft_bak/postgresql-9.3.1/contrib/plproxy-d703683[root@db-172-16-3-150 plproxy-d703683]# export PATH=/home/pg93/pgsql9.3.1/bin:$PATH[root@db-172-16-3-150 plproxy-d703683]# which pg_config[root@db-172-16-3-150 plproxy-d703683]# gmake clean[root@db-172-16-3-150 plproxy-d703683]# gmake[root@db-172-16-3-150 plproxy-d703683]# gmake install

创建proxy库, proxy角色, 在proxy库创建plproxy extension.

pg93@db-172-16-3-150-> psqlpsql (9.3.1)Type "help" for help.postgres=# create role proxy nosuperuser login encrypted password 'proxy';CREATE ROLEdigoal=# create database proxy;CREATE DATABASEdigoal=# \c proxyYou are now connected to database "proxy" as user "postgres".proxy=# create extension plproxy;CREATE EXTENSION

调整proxy库权限

proxy=# grant all on database proxy to proxy;GRANTproxy=# \c proxy proxyYou are now connected to database "proxy" as user "digoal".

创建digoal schema, 目的是和数据节点的schema匹配, 这样的话可以省去在代理函数中写target强行指定schema.

proxy=> create schema digoal;CREATE SCHEMA

创建节点数据库

proxy=> \c postgres postgres You are now connected to database "postgres" as user "postgres". postgres=# create role digoal nosuperuser login encrypted password 'digoal'; postgres=# create database db0;postgres=# create database db1;postgres=# create database db2;postgres=# create database db3;

调整权限, 赋予给后面将要给user mapping中配置的option user权限.

postgres=# grant all on database db0 to digoal;postgres=# grant all on database db1 to digoal;postgres=# grant all on database db2 to digoal;postgres=# grant all on database db3 to digoal;

使用超级用户在proxy数据库中创建server.

proxy=> \c proxy postgresYou are now connected to database "proxy" as user "postgres".proxy=# CREATE SERVER cluster_srv1 FOREIGN DATA WRAPPER plproxy options (connection_lifetime '1800',p0 'dbname=db0 hostaddr=172.16.3.150 port=1921 application_name=test',p1 'dbname=db1 hostaddr=172.16.3.150 port=1921',p2 'dbname=db2 hostaddr=172.16.3.150 port=1921',p3 'dbname=db3 hostaddr=172.16.3.150 port=1921');

创建server时可以使用libpq中的选项. 例如本例使用了application_name.
将server权限赋予给proxy用户.

proxy=# grant usage on FOREIGN server cluster_srv1 to proxy;GRANT

配置proxy用户的连接cluster_srv1的选项.

proxy=# create user mapping for proxy server cluster_srv1 options (user 'digoal');CREATE USER MAPPING

用户proxy连接到cluster_srv1时使用digoal用户连接, 这里不需要配置password, 因为我们将使用trust认证.

修改数据节点的pg_hba.conf
从proxy节点使用digoal用户连接数据库db0, db1, db2, db3使用trust认证.

vi $PGDATA/pg_hba.confhost db0 digoal 172.16.3.150/32 trusthost db1 digoal 172.16.3.150/32 trusthost db2 digoal 172.16.3.150/32 trusthost db3 digoal 172.16.3.150/32 trustpg_ctl reload

使用超级用户创建plproxy函数, 然后把函数权限赋予给proxy权限.

proxy=# CREATE OR REPLACE FUNCTION digoal.dy(sql text) RETURNS SETOF record LANGUAGE plproxy STRICTAS $function$ cluster 'cluster_srv1'; run on all;$function$;proxy=# grant execute on function digoal.dy(text) to proxy;GRANT

在数据节点创建实体函数

proxy=# \c db0 digoaldb0=# CREATE OR REPLACE FUNCTION digoal.dy(sql text) RETURNS SETOF record LANGUAGE plpgsql STRICTAS $function$ declare rec record; begin for rec in execute sql loop return next rec; end loop; return; end;$function$;db0=# \c db1 digoal...db1=# \c db2 digoal...db2=# \c db3 digoal...

在proxy库中就可以查询这个动态SQL了.

proxy=> select * from digoal.dy('select count(*) from pg_class') as t(i int8); i ----- 293 293 293 293(4 rows)proxy=> select sum(i) from digoal.dy('select count(*) from pg_class') as t(i int8); sum ------ 1172(1 row)

几个小的测试 :

一. 修改foreign server测试, 观察连接将重置.
前面那个会话不要断开, 在另一个会话中观察proxy发起的连接到数据节点的连接.

postgres=# select * from pg_stat_activity where usename='digoal'; datid | datname | pid | usesysid | usename | application_name | client_addr | client_hostname | client_port | backend_start | xact_start | query_start | state_change | waiting | state | query -------+---------+------+----------+---------+------------------+--------------+-----------------+-------------+-------------------------------+------------+-------------------------------+-------------------------------+---------+-------+----------------------------------------------------- 91246 | db0 | 8171 | 91250 | digoal | test | 172.16.3.150 | | 47937 | 2013-11-22 17:23:26.138425+08 | | 2013-11-22 17:27:05.539286+08 | 2013-11-22 17:27:05.539745+08 | f | idle | select i::int8 from digoal.dy($1::text) as (i int8) 91247 | db1 | 8172 | 91250 | digoal | | 172.16.3.150 | | 47938 | 2013-11-22 17:23:26.138688+08 | | 2013-11-22 17:27:05.53938+08 | 2013-11-22 17:27:05.539874+08 | f | idle | select i::int8 from digoal.dy($1::text) as (i int8) 91248 | db2 | 8173 | 91250 | digoal | | 172.16.3.150 | | 47939 | 2013-11-22 17:23:26.138957+08 | | 2013-11-22 17:27:05.53938+08 | 2013-11-22 17:27:05.539841+08 | f | idle | select i::int8 from digoal.dy($1::text) as (i int8) 91249 | db3 | 8174 | 91250 | digoal | | 172.16.3.150 | | 47940 | 2013-11-22 17:23:26.139178+08 | | 2013-11-22 17:27:05.539366+08 | 2013-11-22 17:27:05.539793+08 | f | idle | select i::int8 from digoal.dy($1::text) as (i int8)(4 rows)

再次在proxy的同一会话中查询时, 这些会话会复用, 不会断开. 前面已经讲了plproxy是使用长连接的.
如果修改了server, 那么这些连接会断开, 重新连接. 所以不需要担心修改server带来的连接cache问题.

postgres=# \c proxy postgresYou are now connected to database "proxy" as user "postgres".proxy=# alter server cluster_srv1 options (set p1 'dbname=db1 hostaddr=172.16.3.150 port=1921 application_name=abc');ALTER SERVER

再次在proxy的同一会话中查询后, 我们发现4个连接都变了, 说明alter server后, 如果再次发起plproxy函数的查询请求, 那么proxy会重置连接.

proxy=> select sum(i) from digoal.dy('select count(*) from pg_class') as t(i int8); sum ------ 1172(1 row)

在另一会话的查询结果 :

proxy=# select * from pg_stat_activity where usename='digoal'; datid | datname | pid | usesysid | usename | application_name | client_addr | client_hostname | client_port | backend_start | xact_start | query_start | state_change | waiting | state | query -------+---------+------+----------+---------+------------------+--------------+-----------------+-------------+-------------------------------+------------+-------------------------------+-------------------------------+---------+-------+----------------------------------------------------- 91246 | db0 | 8245 | 91250 | digoal | test | 172.16.3.150 | | 47941 | 2013-11-22 17:30:36.933077+08 | | 2013-11-22 17:30:36.936784+08 | 2013-11-22 17:30:36.938837+08 | f | idle | select i::int8 from digoal.dy($1::text) as (i int8) 91248 | db2 | 8247 | 91250 | digoal | | 172.16.3.150 | | 47943 | 2013-11-22 17:30:36.933502+08 | | 2013-11-22 17:30:36.936783+08 | 2013-11-22 17:30:36.938981+08 | f | idle | select i::int8 from digoal.dy($1::text) as (i int8) 91249 | db3 | 8248 | 91250 | digoal | | 172.16.3.150 | | 47944 | 2013-11-22 17:30:36.933731+08 | | 2013-11-22 17:30:36.937147+08 | 2013-11-22 17:30:36.939015+08 | f | idle | select i::int8 from digoal.dy($1::text) as (i int8) 91247 | db1 | 8246 | 91250 | digoal | abc | 172.16.3.150 | | 47942 | 2013-11-22 17:30:36.933288+08 | | 2013-11-22 17:30:36.93757+08 | 2013-11-22 17:30:36.939299+08 | f | idle | select i::int8 from digoal.dy($1::text) as (i int8)(4 rows)

二. run on 的几种形式测试.
在数据节点创建测试表.

proxy=# \c db0 digoaldb0=> create table t(id int);CREATE TABLEdb0=> \c db1You are now connected to database "db1" as user "digoal".db1=> create table t(id int);CREATE TABLEdb1=> \c db2You are now connected to database "db2" as user "digoal".db2=> create table t(id int);CREATE TABLEdb2=> \c db3You are now connected to database "db3" as user "digoal".db3=> create table t(id int);CREATE TABLE

在数据节点创建插入数据的实体函数, 每个节点返回不一样的数字.

\c db0 digoaldb0=> create or replace function digoal.f_test4() returns int as $$declarebegininsert into t(id) values (1);return 0;end;$$ language plpgsql strict;db1=> create or replace function digoal.f_test4() returns int as $$declarebegininsert into t(id) values (1);return 1;end;$$ language plpgsql strict;db2=> create or replace function digoal.f_test4() returns int as $$declarebegininsert into t(id) values (1);return 2;end;$$ language plpgsql strict;db3=> create or replace function digoal.f_test4() returns int as $$declarebegininsert into t(id) values (1);return 3;end;$$ language plpgsql strict;

在proxy节点创建代理函数, 并且将执行权限赋予给proxy用户.

proxy=> \c proxy postgrescreate or replace function digoal.f_test4() returns int as $$cluster 'cluster_srv1';run on 0; -- 在指定的数据节点上运行, 本例可以设置为0到3, 顺序和创建的server中的配置顺序一致. p0, p1, p2, p3$$ language plproxy strict;proxy=# grant execute on function digoal.f_test4() to proxy;GRANTproxy=# \c proxy proxyYou are now connected to database "proxy" as user "proxy".proxy=> select * from digoal.f_test4(); f_test4 --------- 0(1 row)

如果run on 的数字改成0-3以外的数字, 运行时将报错.

proxy=# create or replace function digoal.f_test4() returns int as $$cluster 'cluster_srv1';run on 4; $$ language plproxy strict;CREATE FUNCTIONproxy=# \c proxy proxyYou are now connected to database "proxy" as user "proxy".proxy=> select * from digoal.f_test4();ERROR: PL/Proxy function digoal.f_test4(0): part number out of range

run on any表示随机的选择一个数据节点运行.

proxy=> \c proxy postgresYou are now connected to database "proxy" as user "postgres".proxy=# create or replace function digoal.f_test4() returns int as $$cluster 'cluster_srv1';run on any; $$ language plproxy strict;CREATE FUNCTIONproxy=# \c proxy proxyYou are now connected to database "proxy" as user "proxy".proxy=> select * from digoal.f_test4(); f_test4 --------- 0(1 row)
proxy=> select * from digoal.f_test4(); f_test4 --------- 3(1 row)
proxy=> select * from digoal.f_test4(); f_test4 --------- 2(1 row)
proxy=> select * from digoal.f_test4(); f_test4 --------- 3(1 row)
run on function() 则使用比特计算得到运行节点.proxy=> create or replace function digoal.f(int) returns int as $$select $1;$$ language sql strict;CREATE FUNCTIONproxy=> \c proxy postgresYou are now connected to database "proxy" as user "postgres".proxy=# create or replace function digoal.f_test4() returns int as $$cluster 'cluster_srv1';run on digoal.f(10); $$ language plproxy strict;CREATE FUNCTIONproxy=> select digoal.f_test4(); f_test4 --------- 2(1 row)proxy=> \c proxy postgresYou are now connected to database "proxy" as user "postgres".proxy=# create or replace function digoal.f_test4() returns int as $$cluster 'cluster_srv1';run on digoal.f(11); $$ language plproxy strict;CREATE FUNCTIONproxy=# \c proxy proxyYou are now connected to database "proxy" as user "proxy".proxy=> select digoal.f_test4(); f_test4 --------- 3(1 row)proxy=> \c proxy postgresYou are now connected to database "proxy" as user "postgres".proxy=# create or replace function digoal.f_test4() returns int as $$cluster 'cluster_srv1';run on digoal.f(-11); $$ language plproxy strict;CREATE FUNCTIONproxy=# \c proxy proxyYou are now connected to database "proxy" as user "proxy".proxy=> select digoal.f_test4(); f_test4 --------- 1(1 row)

run on all表示所有数据节点运行. 代理函数必须使用returns setof返回.

proxy=> \c proxy postgresYou are now connected to database "proxy" as user "postgres".proxy=# create or replace function digoal.f_test4() returns int as $$cluster 'cluster_srv1';run on all; $$ language plproxy strict;ERROR: PL/Proxy function digoal.f_test4(0): RUN ON ALL requires set-returning functionproxy=# drop function digoal.f_test4();DROP FUNCTIONproxy=# create or replace function digoal.f_test4() returns setof int as $$cluster 'cluster_srv1';run on all; $$ language plproxy strict;CREATE FUNCTIONproxy=# grant execute on function digoal.f_test4() to proxy;GRANTproxy=# \c proxy proxy You are now connected to database "proxy" as user "proxy".proxy=> select digoal.f_test4(); f_test4 --------- 0 1 2 3(4 rows)

[注意事项]

1. 设计时需要注意

plproxy函数所在的schema尽量和数据节点上实际函数的schema一致.

否则需要在plproxy函数中使用target指定 schema.functionname;

2. 数据节点的个数请保持2^n,

这么做有利于后期的节点扩展, 例如2个节点扩展到4个节点时, 数据不需要发生跨节点的重分布.

例如

mod(x,2)=0 那么mod(x,4)=0或2

mod(x,2)=1 那么mod(x,4)=1或3

比较适合位运算的分布算法.

3. 如果业务为短连接的形式, 那么需要1层连接池, 在应用程序和plproxy数据库之间. 而不是plproxy和数据节点之间.

在应用程序和plproxy之间加连接池后, 其实对于plproxy来说就是长连接了, 所以在plproxy和数据节点之间也就不需要连接池了.

4. 长连接不需要连接池, 因为plproxy和数据节点之间的连接是长连接.

5. plproxy语法 :

connect, cluster, run, select, split, target.

6. 关于连接密码

出于安全考虑, 建议在任何配置中不要出现明文密码, 所以最好是plproxy服务器到数据节点是trust验证, 保护好plproxy即可.

假设plproxy在172.16.3.2上. 数据节点有4个, 库名和用户名都为digoal. 那么在4个节点上配置pg_hba.conf如下.

node0

host digoal digoal 172.16.3.2/32 trust

node1

host digoal digoal 172.16.3.2/32 trust

node2

host digoal digoal 172.16.3.2/32 trust

node3

host digoal digoal 172.16.3.2/32 trust

7. run 详解:

run on <NR>, <NR>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.

8. 一个plproxy中只能出现一条connect语句, 否则报错.

digoal=# create or replace function f_test3() returns setof int8 as $$
connect 'hostaddr=172.16.3.150 dbname=db0 user=digoal port=1921';
connect 'hostaddr=172.16.3.150 dbname=db1 user=digoal port=1921';
select count(*) from pg_class;
$$ language plproxy strict;
ERROR: PL/Proxy function postgres.f_test3(0): Compile error at line 2: Only one CONNECT statement allowed

9. 不要把plproxy语言的权限赋予给普通用户, 因为开放了trust认证, 如果再开放plproxy语言的权限是非常危险的.

正确的做法是使用超级用户创建plproxy函数, 然后把函数的执行权限赋予给普通用户.

千万不要这样省事 :

update pg_language set lanpltrusted='t' where lanname='plproxy';

10. 如果有全局唯一的序列需求, 可以将序列的步调调整一下, 每个数据节点使用不同的初始值.

例如

db0=# create sequence seq1 increment by 4 start with 0;
CREATE SEQUENCE

db1=# create sequence seq1 increment by 4 start with 1;

db2=# create sequence seq1 increment by 4 start with 2;

db3=# create sequence seq1 increment by 4 start with 3;

考虑到扩容, 可以将步调调比较大, 例如1024. 那么可以容纳1024个节点.

...

[参考]

1. http://kaiv.wordpress.com/2007/07/27/postgresql-cluster-partitioning-with-plproxy-part-i/

2. http://kaiv.wordpress.com/2007/09/02/postgresql-cluster-partitioning-with-plproxy-part-ii/

3. http://blog.163.com/digoal@126/blog/static/163877040201041111304328/

4. http://blog.163.com/digoal@126/blog/static/1638770402010411113114315/

5. http://blog.163.com/digoal@126/blog/static/163877040201192535630895/

6. http://www.postgresql.org/docs/9.3/static/libpq-connect.html#LIBPQ-CONNSTRING

7. http://git.postgresql.org/gitweb/?p=plproxy.git;a=summary

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标签： postgresql 数据库分布式扩展

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