搭pl/proxy集群

最近朋友要上一个系统，设计百亿级数据。我去帮着搭建系统，采用pg/proxy集群，业务相关就不说了，这里就把简单技术验证放出来。相关人员比较保守，就用了OS官方的安装包，pg版本9.1.

规划中两台服务器上验证，一个上三个实例（一个实例做代理，另外两个做数据节点），一个上两个实例（做数据节点）

数据节目录如下，不过是在两台服务器上，如上所说。

/opt/pg91/pgdata0

/opt/pg91/pgdata1

/opt/pg91/pgdata2

/opt/pg91/pgdata3

/opt/pg91/pgdata4

0

第一部分，安装

1

查询可安装版本

[email protected]:~$ apt-cache search postgres | grep 9

libpgtypes3 - shared library libpgtypes for PostgreSQL 9.1

postgresql-9.1 - object-relational SQL database, version 9.1 server

。。。

postgresql-9.1-slony1-2 - replication system for PostgreSQL: PostgreSQL 9.1 server plug-in

skytools-modules-9.1 - PostgreSQL 9.1 modules for skytools

2

装

[email protected]:~$ sudo apt-get install -y postgresql-9.1 postgresql-client-9.1 postgresql-contrib-9.1 postgresql-server-dev-9.1

... ...

update-alternatives: using /usr/share/postgresql/9.1/man/man1/postmaster.1.gz to provide /usr/share/man/man1/postmaster.1.gz (postmaster.1.gz) in auto mode.

* Starting PostgreSQL 9.1 database server

...done.

Setting up postgresql-contrib-9.1 (9.1.14-0ubuntu0.12.04) ...

Setting up postgresql-server-dev-9.1 (9.1.14-0ubuntu0.12.04) ...

Processing triggers for libc-bin ...

ldconfig deferred processing now taking place

看到上面这句就ok了，就是说有些事情在以上安装过程中给deferred（推迟）了，推迟到现在集中处理了。

3

查看，已经跑起来了

[email protected]:~$ ps -ef | grep postgres

postgres  8362     1  0 17:22 ?        00:00:00 /usr/lib/postgresql/9.1/bin/postgres -D /var/lib/postgresql/9.1/main -c config_file=/etc/postgresql/9.1/main/postgresql.conf

postgres  8364  8362  0 17:22 ?        00:00:00 postgres: writer process

postgres  8365  8362  0 17:22 ?        00:00:00 postgres: wal writer process

postgres  8366  8362  0 17:22 ?        00:00:00 postgres: autovacuum launcher process

postgres  8367  8362  0 17:22 ?        00:00:00 postgres: stats collector process

zxw       8425  1486  0 17:34 pts/0    00:00:00 grep --color=auto postgres

[email protected]:~$

[email protected]:~$  /etc/init.d/postgresql status

Running clusters: 9.1/main

4

这样登录不行，默认Peer authentication

[email protected]:~$ psql -U postgres postgres

psql: FATAL:  Peer authentication failed for user "postgres"

[email protected]:~$

5

这样登录

[email protected]:~$ sudo -u postgres psql

[sudo] password for zxw:

psql (9.1.14)

Type "help" for help.

postgres=# \q

5

确认Peer authentication

[email protected]:~$ sudo nl /etc/postgresql/9.1/main/pg_hba.conf | more

79  # Database administrative login by Unix domain socket

80  local   all             postgres                                peer

81  # TYPE  DATABASE        USER            ADDRESS                 METHOD

82  # "local" is for Unix domain socket connections only

83  local   all             all                                     peer

84  # IPv4 local connections:

85  host    all             all             127.0.0.1/32            md5

peer

Obtain the client’s operating system user name from the operating system and check if it

matches the requested database user name. This is only available for local connections. See

Section 19.3.7 for details.

给改成md5认证，

6

安装时没提示设置密码，超级用户密码随机了一个，给修改一下

postgres=# select * from pg_user;

usename  | usesysid | usecreatedb | usesuper | usecatupd | userepl |  passwd  | valuntil | useconfig

----------+----------+-------------+----------+-----------+---------+----------+----------+-----------

postgres |       10 | t           | t        | t         | t       | ******** |          |

(1 row)

postgres=# alter user postgres password ‘postgres‘;

ALTER ROLE

postgres=# select * from pg_user;

usename  | usesysid | usecreatedb | usesuper | usecatupd | userepl |  passwd  | valuntil | useconfig

----------+----------+-------------+----------+-----------+---------+----------+----------+-----------

postgres |       10 | t           | t        | t         | t       | ******** |          |

(1 row)

7

md5 authentication ok：

[email protected]:~$ psql -h 127.0.0.1 -U postgres postgres

Password for user postgres:

psql (9.1.14)

SSL connection (cipher: DHE-RSA-AES256-SHA, bits: 256)

Type "help" for help.

postgres=#

8

修改监听地址等，加载配置参数

[email protected]:~$ sudo -u postgres /etc/init.d/postgresql reload

* Reloading PostgreSQL 9.1 database server

...done.

[email protected]:~$

9

验证ok

[email protected]:~$ psql -h127.0.0.1 -Upostgres postgres

Password for user postgres:

psql (9.1.14)

SSL connection (cipher: DHE-RSA-AES256-SHA, bits: 256)

Type "help" for help.

postgres=# show all ;

name               |                 setting                  |                                                          description

---------------------------------+------------------------------------------+-------------------------------------------------------------------------------------------------------------------------------

allow_system_table_mods         | off                                      | Allows modifications of the structure of system tables.

。。。。。。

listen_addresses                | *                                        | Sets the host name or IP address(es) to listen to.

lo_compat_privileges            | off                                      | Enables backward compatibility mode for privilege checks on large objects.

local_preload_libraries         |                                          | Lists shared libraries to preload into each backend.

10

验证ok

[email protected]:~$ psql -h192.168.11.131 -Upostgres postgres

Password for user postgres:

psql (9.1.14)

SSL connection (cipher: DHE-RSA-AES256-SHA, bits: 256)

Type "help" for help.

postgres=#

11

ubuntu12上官方pg包安装完后的目录基本如下：

istall directory

/usr/lib/postgresql/9.1/bin/postgres      proc

/var/lib/postgresql/9.1/main                             data

/etc/postgresql/9.1/main/postgresql.conf  option file

/usr/share/postgresql/9.1/contrib/

/usr/share/postgresql/9.1/extension/

/usr/share/postgresql-common/

第二部分

初始化n个实例

1

准备目录

[email protected]:~# mkdir /opt/pg91

[email protected]:~# chown postgres:postgres /opt/pg91/

2

初始化一个实例

[email protected]:~# sudo -u postgres /usr/lib/postgresql/9.1/bin/initdb -E utf8 -Upostgres --locale=C -W -D /opt/pg91/pgdata1

could not change directory to "/root"

The files belonging to this database system will be owned by user "postgres".

This user must also own the server process.

The database cluster will be initialized with locale C.

The default text search configuration will be set to "english".

creating directory /opt/pg91/pgdata1 ... ok

creating subdirectories ... ok

selecting default max_connections ... 100

。。。

Enter new superuser password:

。。。

vacuuming database template1 ... ok

copying template1 to template0 ... ok

copying template1 to postgres ... ok

WARNING: enabling "trust" authentication for local connections

You can change this by editing pg_hba.conf or using the -A option the

next time you run initdb.

Success. You can now start the database server using:

/usr/lib/postgresql/9.1/bin/postgres -D /opt/pg91/pgdata1

or

/usr/lib/postgresql/9.1/bin/pg_ctl -D /opt/pg91/pgdata1 -l logfile start

[email protected]:~#

3

查看数据集目录

[email protected]:~# ll /opt/pg91/pgdata1/

total 88

drwx------ 13 postgres postgres  4096 Oct 23 15:49 ./

drwxr-xr-x  3 postgres postgres  4096 Oct 23 15:49 ../

drwx------  5 postgres postgres  4096 Oct 23 15:49 base/

drwx------  2 postgres postgres  4096 Oct 23 15:49 global/

drwx------  2 postgres postgres  4096 Oct 23 15:49 pg_clog/

-rw-------  1 postgres postgres  4476 Oct 23 15:49 pg_hba.conf

-rw-------  1 postgres postgres  1636 Oct 23 15:49 pg_ident.conf

drwx------  4 postgres postgres  4096 Oct 23 15:49 pg_multixact/

drwx------  2 postgres postgres  4096 Oct 23 15:49 pg_notify/

drwx------  2 postgres postgres  4096 Oct 23 15:49 pg_serial/

drwx------  2 postgres postgres  4096 Oct 23 15:49 pg_stat_tmp/

drwx------  2 postgres postgres  4096 Oct 23 15:49 pg_subtrans/

drwx------  2 postgres postgres  4096 Oct 23 15:49 pg_tblspc/

drwx------  2 postgres postgres  4096 Oct 23 15:49 pg_twophase/

-rw-------  1 postgres postgres     4 Oct 23 15:49 PG_VERSION

drwx------  3 postgres postgres  4096 Oct 23 15:49 pg_xlog/

-rw-------  1 postgres postgres 19129 Oct 23 15:49 postgresql.conf

4

搞个放日志的地方

[email protected]:~# mkdir /opt/pg91/pgdata1/pg_log

[email protected]:~# chown postgres:postgres /opt/pg91/pgdata1/pg_log/

[email protected]:~# chmod 700 /opt/pg91/pgdata1/pg_log/

修改认证监听等相关参数，后跑一个

[email protected]:~# sudo -u postgres /usr/lib/postgresql/9.1/bin/pg_ctl -D /opt/pg91/pgdata1 -l /opt/pg91/pgdata1/pg_log/pg.log start

重复以上跑起5个实例。

第三部分

安装pl/proxy

1

查一下能装啥

[email protected]:~$  apt-cache search plproxy

postgresql-9.1-plproxy - database partitioning system for PostgreSQL 9.1

2

装

[email protected]:~$ sudo apt-get install -y postgresql-9.1-plproxy

[sudo] password for zxw:

Reading package lists... Done

Building dependency tree

Reading state information... Done

The following NEW packages will be installed:

postgresql-9.1-plproxy

0 upgraded, 1 newly installed, 0 to remove and 69 not upgraded.

Need to get 65.3 kB of archives.

After this operation, 268 kB of additional disk space will be used.

Get:1 http://hk.archive.ubuntu.com/ubuntu/ precise/universe postgresql-9.1-plproxy amd64 2.3-1 [65.3 kB]

Fetched 65.3 kB in 10s (6,138 B/s)

Selecting previously unselected package postgresql-9.1-plproxy.

(Reading database ... 58432 files and directories currently installed.)

Unpacking postgresql-9.1-plproxy (from .../postgresql-9.1-plproxy_2.3-1_amd64.deb) ...

Setting up postgresql-9.1-plproxy (2.3-1) ...

[email protected]:~$

3

规划

proxy node:

ip

port portN

create user beiigang

create user proxy

create database proxy;

schema beiigang

data node:

ip

port portN

create user beiigang

create user devart

create database datadb

schema beiigang

4

跑规划

#

#proxy

#

create role beiigang superuser login encrypted password ‘beiigang‘;

create role proxy nosuperuser nocreatedb nocreaterole noinherit login encrypted password ‘proxy‘;

create database proxy with owner beiigang template template0 encoding ‘UTF8‘ lc_collate ‘en_US.UTF-8‘ lc_ctype ‘en_US.UTF-8‘;

grant all on database proxy to proxy;

create schema proxy authorization proxy;

#

#data node

#

create role beiigang superuser login encrypted password ‘beiigang‘;

create role devart nosuperuser nocreatedb nocreaterole noinherit login encrypted password ‘devart‘;

create database datadb with owner beiigang template template0 encoding ‘UTF8‘ lc_collate ‘en_US.UTF-8‘ lc_ctype ‘en_US.UTF-8‘;

grant all on database datadb to devart;

create schema devart authorization devart;

#

#proxy node

#

postgres=# create role beiigang superuser login encrypted password ‘beiigang‘;

CREATE ROLE

postgres=# create role proxy nosuperuser nocreatedb nocreaterole noinherit login encrypted password ‘proxy‘;

CREATE ROLE

postgres=# create database proxy with owner beiigang template template0 encoding ‘UTF8‘ lc_collate ‘en_US.UTF-8‘ lc_ctype ‘en_US.UTF-8‘;

CREATE DATABASE

postgres=# grant all on database proxy to proxy;

GRANT

proxy=# create schema proxy authorization proxy;

CREATE SCHEMA

#

#data node

#

postgres=# create role beiigang superuser login encrypted password ‘beiigang‘;

CREATE ROLE

postgres=# create role datasch nosuperuser nocreatedb nocreaterole noinherit login encrypted password ‘datasch‘;

CREATE ROLE

postgres=# create database datadb with owner beiigang template template0 encoding ‘UTF8‘ lc_collate ‘en_US.UTF-8‘ lc_ctype ‘en_US.UTF-8‘;

CREATE DATABASE

postgres=# grant all on database datadb to datasch;

GRANT

datadb=> create schema datasch authorization datasch;

CREATE SCHEMA

5

在代理上跑plproxy.sql

[email protected]:~#  psql -h ip -p portN -Upostgres -f /usr/share/postgresql/9.1/contrib/plproxy.sql proxy

Password for user postgres:

CREATE FUNCTION

CREATE LANGUAGE

CREATE FUNCTION

CREATE FOREIGN DATA WRAPPER

plproxy.sql的内容如下

## nl /usr/share/postgresql/9.1/contrib/plproxy.sql | more

#

#     1  -- handler function

#     2  CREATE FUNCTION plproxy_call_handler ()

#     3  RETURNS language_handler AS ‘$libdir/plproxy‘ LANGUAGE C;

#

#     4  -- language

#     5  CREATE LANGUAGE plproxy HANDLER plproxy_call_handler;

#

#     6  -- validator function

#     7  CREATE FUNCTION plproxy_fdw_validator (text[], oid)

#     8  RETURNS boolean AS ‘$libdir/plproxy‘ LANGUAGE C;

#

#     9  -- foreign data wrapper

#    10  CREATE FOREIGN DATA WRAPPER plproxy VALIDATOR plproxy_fdw_validator;

6

查看上面创建的对象

#proxy=# select * from pg_language;

# lanname  | lanowner | lanispl | lanpltrusted | lanplcallfoid | laninline | lanvalidator | lanacl

#----------+----------+---------+--------------+---------------+-----------+--------------+--------

# internal |       10 | f       | f            |             0 |         0 |         2246 |

# c        |       10 | f       | f            |             0 |         0 |         2247 |

# sql      |       10 | f       | t            |             0 |         0 |         2248 |

# plpgsql  |       10 | t       | t            |         11678 |     11679 |        11680 |

# plproxy  |       10 | t       | f            |         16399 |         0 |            0 |

#(5 rows)

#

#proxy=# select * from pg_foreign_data_wrapper;

# fdwname | fdwowner | fdwhandler | fdwvalidator | fdwacl | fdwoptions

#---------+----------+------------+--------------+--------+------------

# plproxy |       10 |          0 |        16401 |        |

#(1 row)

#还drop了一回，这个不要跑啊

#proxy=# drop language plproxy cascade;

#DROP LANGUAGE

#proxy=#

#proxy=# drop FOREIGN DATA WRAPPER plproxy cascade;

#DROP FOREIGN DATA WRAPPER

#proxy=#

#proxy=# drop function plproxy_call_handler();

#DROP FUNCTION

#proxy=#

#proxy=# drop function plproxy_fdw_validator (text[], oid);

#DROP FUNCTION

#

7

授权

########这句报错

#proxy=# grant usage on language plproxy to proxy;

#ERROR:  language "plproxy" is not trusted

#HINT:  Only superusers can use untrusted languages.

########下面的ok

#proxy=# grant usage on foreign data wrapper  plproxy to proxy;

#GRANT

#proxy=# grant usage on foreign server cluster_art to proxy;

#GRANT

8

proxy node创建plproxy server

#super user do

#drop server cluster_art;

CREATE SERVER cluster_art FOREIGN DATA WRAPPER plproxy OPTIONS

(connection_lifetime ‘1800‘,

p0 ‘dbname=datadb port=9901 host=192.168.11.196 application_name=testart‘,

p1 ‘dbname=datadb port=9902 host=192.168.11.197 ‘,

p2 ‘dbname=datadb port=9903 host=192.168.11.196 ‘,

p3 ‘dbname=datadb port=9904 host=192.168.11.197 ‘);

9

proxy node授权

grant usage on foreign server cluster_art to proxy;

10

proxy node创建user mapping

create user mapping for proxy server cluster_art options (user ‘devart‘, password ‘xxxxxxxx‘);

plproxy集群搭好了。。。。。。

第四部分

测试

这儿前前后后测试了不少场景，花了好几天，基本上没有记录，下面的也不是一个完整一致的测试，只是记录到这儿，大家就不要看了，看了就晕了

--test

CREATE OR REPLACE FUNCTION proxy.test_pl_clust(sql text)

RETURNS SETOF record

LANGUAGE plproxy

STRICT

AS $function$

cluster ‘cluster_art‘;

run on all;

target devart.test_pl_clust;

$function$;

grant execute on function datasch.test_pl_clust(text) to proxy;

CREATE OR REPLACE FUNCTION test_pl_clust(sql text)

RETURNS SETOF record

LANGUAGE plpgsql

STRICT

AS $function$

declare

rec record;

begin

for rec in execute sql loop

return next rec;

end loop;

return;

end;

$function$;

select * from datasch.test_pl_clust(‘select count(*) from pg_class‘) as t(i int8);

proxy=> select * from test_pl_clust(‘select count(*) from pg_user‘) as t(k int8);

k

---

3

3

3

3

(4 rows)

proxy=> select sum(k) from test_pl_clust(‘select count(*) from pg_user‘) as t(k int8);

sum

-----

12

(1 row)

附记

1

pl/proxy源码下载地址，好像是吧

http://pgfoundry.org/projects/plproxy

2

官网上记录的一个bug

dumpall 不能正常工作

http://pgfoundry.org/tracker/index.php?func=detail&aid=1011283&group_id=1000207&atid=814

pg_dumpall sorts ‘create server FOREIGN DATA WRAPPER‘ options

(keys) as varchar and not as integer.

Example from dumped sql (see "pX" option key):

CREATE SERVER can_master_cluster FOREIGN DATA WRAPPER plproxy OPTIONS (

connection_lifetime ‘1800‘,

p0 ‘dbname=database11 host=xxx-11 port=9811‘,

p1 ‘dbname=database12 host=xxx-12 port=9812‘,

p10 ‘dbname=database21 host=xxx-21 port=9821‘,

p11 ‘dbname=database22 host=xxx-22 port=9822‘,

p12 ‘dbname=database23 host=xxx-23 port=9823‘,

p13 ‘dbname=database24 host=xxx-24 port=9824‘,

p14 ‘dbname=database25 host=xxx-25 port=9825‘,

p15 ‘dbname=database26 host=xxx-26 port=9826‘,

p2 ‘dbname=database13 host=xxx-13 port=9813‘,

p3 ‘dbname=database14 host=xxx-14 port=9814‘,

p4 ‘dbname=database15 host=xxx-15 port=9815‘,

p5 ‘dbname=database16 host=xxx-16 port=9816‘,

p6 ‘dbname=database17 host=xxx-17 port=9817‘,

p7 ‘dbname=database18 host=xxx-18 port=9818‘,

p8 ‘dbname=database19 host=xxx-19 port=9819‘,

p9 ‘dbname=database20 host=xxx-20 port=9820‘

);

which causes next error during the load:

ERROR: Pl/Proxy: partitions must be numbered consecutively

HINT: next valid partition number is 2

STATEMENT: CREATE SERVER can_master_cluster ...

Old 9.0 ‘pg_dumpall‘ doing job correct.

参考

http://plproxy.projects.pgfoundry.org/doc/tutorial.html

http://plproxy.projects.pgfoundry.org/doc/syntax.html

http://www.linuxidc.com/Linux/2011-08/41600.htm

http://blog.163.com/[email protected]/blog/static/1638770402013102242543765/

-----------------

转载请著明出处：

blog.csdn.net/beiigang

时间： 2024-10-25 05:07:05

搭pl/proxy集群的相关文章

假设让我搭一个Linux集群--指定各个机器名字

centOS7设置主机名:命令hostname可以查看当前主机名 虚招(临时的):重启机器后失效: hostname  XXX 实招(永久的): 招式一: 将/etc/sysconfig/network ,把hostname栏目修改  (虽有效,但非官方建议) 招式二:将/etc/hostname  中值修改 (官方建议) 招式三:使用hostnamectl命令:hostnamectl set-hostname 主机名       其他招式:图形化界面,第三方工具-- 注意:在centos7/r

Kubernetes(K8S)集群在centos7.4下创建

自己在搭Kubernetes(K8S)集群下遇到的坑写一点随笔. 本次采用192.168.60.21,192.168.60.22,192.168.60.23作为需要装的服务器. master需要安装etcd, flannel,docker, kubernetes   192.168.60.21 yum –y install etcd yum –y install flannel yum –y install docker yum –y install kubernetes 分支上安装flanne

Java企业级电商项目实战 Tomcat集群与Redis分布式

本套课程包含:java电商项目实战课程 Tomcat集群视频教程 Redis项目实战课程课程目录1-1 课程导学1-2 大型Java项目架构演进解析1-3 一期课程与问答服务回顾1-4 一期项目结构和代码回顾1-5 课程使用系统及技术版本介绍(一期+二期)1-6 二期项目初始化第2章 Lombok框架集成及原理解析本章会对Lombok框架进行介绍,同时会讲解Lombok的原理.并手把手领着小伙伴们实战,引入Lombok以及IDE安装Lombok插件.然后会带着大家实战Coding,讲解@Data

# IT明星不是梦 #MySQL高可用集群之基于MyCat部署HaProxy实现高可用

基于MyCat部署HaProxy实现高可用 在实际项目中, Mycat 服务也需要考虑高可用性,如果 Mycat 所在服务器出现宕机,或 Mycat 服务故障,需要有备机提供服务,需要考虑 Mycat 集群. 一.高可用方案 可以使用 HAProxy+Keepalived配合两台MyCat搭起MyCat集群,实现高可用性. HAProxy实现了MyCat多节点的集群高可用和负载均衡,而 HAProxy自身的高可用则可以通过Keepalived来实现. 架构图: 于上一个博客的环境部署(MySQL

[k8s]通过svc来访问集群podhttp://api:8080/api/v1/namespaces/default/services/mynginx/proxy/

通过http://api:8080/api/v1/namespaces/default/services/mynginx/proxy/ 通过svc访问集群报错 我想通过类似这种模式来访问我的集群 http://192.168.14.11:8080/api/v1/namespaces/default/services/mynginx/proxy/ http://192.168.14.11:8080/api/v1/namespaces/kube-system/services/kubernetes-

flume-ng 集群搭脚本

#!/bin/bash # author: xirong # date : 2015-02-06 ##### 搭建 flume 集群的脚本 # 注意: # 1. 需要 jdk7 环境,如果没有 Java 环境,请配置 # 2. 有 /home/work 目录,否则无法安装 # #### # 压缩文件解压 tar -zxf apache-flume-1.5.2-bin.tar.gz -C /home/work/flume_cluster/ # 配置flume环境 echo '## flume co

第 二 十 七 天 ：HA 高 可 用 集 群 搭 建

小Q:凡事都要看得远一点,再远一点,当你迈出第一步,心中必须装着第三步, 第二步才能作为你的筹码,没有筹码的人生, 注定会生存在别人的股掌之中. 今天学了一个特别好的知识,我发现我最近的进度慢,情有可原,一整天就只是看两三个知识点,但是每个知识点我都会研究好长时间,虽然我知道过后我会忘,但 大概我再复习的时候,原理我不会忘,第一遍的目的达到了: 简 介 HA(High Available), 高可用性集群,又被叫做双机热备(Active/Passive),用于关键性业务;是保证业务连续性的有效解

第 二 十 八 天 ：高 可 用 负 载 均 衡 集 群 搭 建

小Q: 一直努力着,努力着,偶尔停下来歇歇,又要振作精神,继续努力着, 努力着,实现我的愿望:不敢奢望. 前面我们用heartbeat配置了高可用集群,用Lvs配置了负载均衡集群:而现在我们可以将两者的功能合二为一,用前面介绍高可用的时候讲到了另一个开源软件keepalived和LVS的ipvsadm合作完成: 一.简介: keepalived是一个类似于layer3, 4 & 7交换机制的软件,也就是我们平时说的第3层.第4层和第7层交换.作用是检测web服务器的状态,如果有一台web服务器工

PostgreSQL高可用性、负载均衡、复制与集群方案介绍

目录[-] 一.高可用性.负载均衡.复制的几个方案比较: 二.多节点集群方案比较 9.3官方文档(中文):http://58.58.27.50:8079/doc/html/9.3.1_zh/high-availability.html 复制.集群和连接池: https://wiki.postgresql.org/wiki/Replication,_Clustering,_and_Connection_Pooling 集群方案功能列表: http://blog.osdba.net/46.html