PostgreSQL Cluster

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　　/data


=============================================================
3. Configuration
=============================================================
(EX.System Composition)

        |
     ((Load Balance Server))
     ( hostname: lb.hoo.com)
     ( receive port:5432 )
     ( recovery port:6101)
     ( lifecheck port:6201)
        |
----------+-------------+------------+----------
    |        |
((Cluster DB 1  ))  ((Cluster DB 2  ))
( hostname:c1.hoo.com)  ( hostname:c2.hoo.com)
( receive port: 5432 )  ( receive port:5432)
( recovery port:7101 )  ( recovery port: 7102 )
( lifecheck port:7201 ) ( lifecheck port: 7202 )
    |        |
----------+-------------+------------+----------
        |
     ((Replication Server))
     ( hostname:pgr.hoo.com)
     ( receive port:8001 )
     ( recovery port:8101)
     ( lifecheck port:8201)


3-1. Load Balance Server

The setup file of load balance server is copied from the sample file and edited.
(the sample file is installed '/usr/local/pgsql/etc' in default)
----------------------------------------------------------------
$cd /usr/local/pgsql/etc
$cp pglb.conf.sample pglb.conf
----------------------------------------------------------------

In the case of the above system composition example,
the setup example of pglb.conf file is as the following

#============================================================
#    Load Balance Server configuration file
#-------------------------------------------------------------
# file: pglb.conf
#-------------------------------------------------------------
# This file controls:
#   o which hosts are db cluster server
#   o which portuse connect to db cluster server
#   o how many connections are allowed on each DB server
#============================================================
#-------------------------------------------------------------
# set cluster DB server information
#        o Host_Name : hostname
#        o Port : connection for postmaster
#        o Max_Connection : maximun number of connection to postmaster
#-------------------------------------------------------------
<Cluster_Server_Info>;
  <Host_Name>; c1.hoo.com</Host_Name>;
  <Port>;  5432      </Port>;
  <Max_Connect>; 32       </Max_Connect>;
</Cluster_Server_Info>;
<Cluster_Server_Info>;
  <Host_Name>; c2.hoo.com</Host_Name>;
  <Port>;  5432      </Port>;
  <Max_Connect>; 32       </Max_Connect>;
</Cluster_Server_Info>;
#-------------------------------------------------------------
# set Load Balance server information
#        o Receive_Port : connection from client
#        o Recovery_Port : connection for recovery process
#        o Max_Cluster_Num : maximun number of cluster DB servers
#        o Use_Connection_Pooling : use connection pool [yes/no]
#        o Max_Pool_Each_Server : number of pool connections/DB server
#-------------------------------------------------------------
<Receive_Port>;  5432      </Receive_Port>;
<Recovery_Port>; 6101      </Recovery_Port>;
<LifeCheck_Port>;6201      </LifeCheck_Port>;
<Max_Cluster_Num>; 128     </Max_Cluster_Num>;
<Use_Connection_Pooling>; yes    </Use_Connection_Pooling>;
<Max_Pool_Each_Server>; 1    </Max_Pool_Each_Server>;

3-2. Cluster DB Server

The Cluster DB server need edit two configuration files
('pg_hba.conf' and 'cluster.conf').
These files are create under the $PG_DATA directory after 'initdb'.

A. pg_hba.conf
Permission to connect DB via IP connectoins is need for this system.

B. cluster.conf
In the case of the above system composition example,
the setup example of cluster.conf file is as the following

#============================================================
#    Cluster DB Server configuration file
#-------------------------------------------------------------
# file: cluster.conf
#-------------------------------------------------------------
# This file controls:
#   o which hosts & port are replication server
#   o which port use for replication request to replication server
#   o which command use for recovery function
#
#============================================================
#-------------------------------------------------------------
# set cluster DB server information
#        o Host_Name : hostname
#        o Port : connection for postmaster
#        o Recovery_Port : connection for recovery process
#-------------------------------------------------------------
<Replicate_Server_Info>;
    <Host_Name>; pgr.hoo.com </Host_Name>;
    <Port>; 8001 </Port>;
    <Recovery_Port>; 8101 </Recovery_Port>;
    <LifeCheck_Port>; 8201 </LifeCheck_Port>;
</Replicate_Server_Info>;
#-------------------------------------------------------------
# set Cluster DB Server information
#        o Recovery_Port : connection for recovery
#        o Rsync_Path : path of rsync command
#        o Rsync_Option : file transfer option for rsync
#   o When_Stand_Alone : When all replication servers fell,
#          you can set up two kinds of permittion,
#          "real_only" or "read_write".
#-------------------------------------------------------------
<Recovery_Port>;  7101   </Recovery_Port>;
<LifeCheck_Port>; 7201   </LifeCheck_Port>;
<Rsync_Path>;   /usr/bin/rsync </Rsync_Path>;
<Rsync_Option>; ssh -1   </Rsync_Option>;
<When_Stand_Alone>; read_only  </When_Stand_Alone>;
<Status_Log_File>;/tmp/cluster.sts </Status_Log_File>;
<Error_Log_File>; /tmp/cluster.log</Error_Log_File>;
#-------------------------------------------------------------
# set partitional replicate control information
# set DB name and Table name to stop reprication
#   o DB_Name : DB name
#   o Table_Name : table name
#-------------------------------------------------------------
#<Not_Replicate_Info>;
#  <DB_Name>; test_db  </DB_Name>;
#  <Table_Name>;log_table  </Table_Name>;
#</Not_Replicate_Info>;

3-3. Replication Server

The setup file of replication server is copied from the sample file and edited.
(the sample file is installed '/usr/local/pgsql/etc' in default)
----------------------------------------------------------------
$cd /usr/local/pgsql/etc
$cp pgreplicate.conf.sample pgreplicate.conf
----------------------------------------------------------------
In the case of the above system composition example,
the setup example of pgreplicate.conf file is as the following

#============================================================
#     PGReplicate configuration file
#-------------------------------------------------------------
# file: pgreplicate.conf
#-------------------------------------------------------------
# This file controls:
#   o which hosts & port are cluster server
#   o which port use for replication request from cluster server
#============================================================
#-------------------------------------------------------------
# set cluster DB server information
#        o Host_Name : hostname
#        o Port : connection for postmaster
#        o Recovery_Port : connection for recovery
#-------------------------------------------------------------
<Cluster_Server_Info>;
  <Host_Name>;  c1.hoo.com  </Host_Name>;
  <Port>;   5432    </Port>;
  <Recovery_Port>;7101    </Recovery_Port>;
    <LifeCheck_Port>; 7201    </LifeCheck_Port>;
</Cluster_Server_Info>;
<Cluster_Server_Info>;
  <Host_Name>;  c2.hoo.com  </Host_Name>;
  <Port>;   5432    </Port>;
  <Recovery_Port>;7101    </Recovery_Port>;
    <LifeCheck_Port>; 7201    </LifeCheck_Port>;
</Cluster_Server_Info>;
#-------------------------------------------------------------
# set Load Balance server information
#        o Host_Name : hostname
#        o Recovery_Port : connection for recovery
#-------------------------------------------------------------
<LoadBalance_Server_Info>;
  <Host_Name>;   lb.hoo.com </Host_Name>;
  <Recovery_Port>; 6101   </Recovery_Port>;
    <LifeCheck_Port>;6201   </LifeCheck_Port>;
</LoadBalance_Server_Info>;
#-------------------------------------------------------------
# set PGReplicate server information
#        o Replicate_Port : connection for reprication
#        o Recovery_Port : connection for recovery
#-------------------------------------------------------------
<Replication_Port>;  8001   </Replication_Port>;
<Recovery_Port>;   8101   </Recovery_Port>;
<LifeCheck_Port>;  8201   </LifeCheck_Port>;


=============================================================
4. Start Up / Stop
=============================================================

4-1. replication server

A. Start replication server
----------------------------------------------------------------
$ /usr/local/pgsql/bin/pgreplicate -D /usr/local/pgsql/etc
----------------------------------------------------------------

B. Stop replication server
----------------------------------------------------------------
$ /usr/local/pgsql/bin/pgreplicate -D /usr/local/pgsql/etc stop
----------------------------------------------------------------

usage: pgreplicate [-D path_of_config_file] [-W path_of_work_files] [-U login us
er][-l][-n][-v][-h][stop]
  -l: print error logs in the log file.
  -n: don't run in daemon mode.
  -v: debug mode. need '-n' flag
  -h: print this help
  stop: stop pgreplicate
(config file default path: ./pgreplicate.conf)

4-2. cluster DB server
$PG_HOME = /usr/local/pgsql
$PG_DATA = /usr/local/pgsql/data

A. Start cluster DB server
----------------------------------------------------------------
$ /usr/local/pgsql/bin/pg_ctl -D /usr/local/pgsql/data -o "-i" start
----------------------------------------------------------------

B. Stop cluster DB server
----------------------------------------------------------------
$ /usr/local/pgsql/bin/pg_ctl -D /usr/local/pgsql/data stop
----------------------------------------------------------------

4-3. load balance server

A. Start load balance server
----------------------------------------------------------------
$ /usr/local/pgsql/bin/pglb -D /usr/local/pgsql/etc
----------------------------------------------------------------

B. Stop load balance server
----------------------------------------------------------------
$ /usr/local/pgsql/bin/pglb -D /usr/local/pgsql/etc stop
----------------------------------------------------------------

usage: pglb [-D path_of_config_file] [-W path_of_work_files] [-n][-v][-h][stop]
  -l: print error logs in the log file.
  -n: don't run in daemon mode.
  -v: debug mode. need '-n' flag
  -h: print this help
  stop: stop pglb
  (config file default path: ./pglb.conf)
　　这是postgresql数据库集群的安装原文
以下是我对他的一些理解与解释：

部署postgresql数据库集群至少需要安装四个数据库

1、balanceDB数据库(以下简称平行数据库)，字面为平衡或并行
处理数据库。他必需定义好节点数据库信息.不需要创建实际的数据库。

2、ClusterDB集群节点数据库二个(以下简称节点数据库)。单个话就不是集群了。这不废话吗？,他必需定义好本节点信息（是只读还是读写都可以）与调度与决策处理数据信息。(节点数据库必需创建数据库，即initdb啦)

3、pgreplicateDB调度与决策处理数据库（以下简称调度数据库)。他必需要定义好并行处理数据库信息、节点数据库信息。(调度与决策数据库不需要创建数据库）。


以下为我的推断：

当客户端访问数据库时候的一个流程。

我们访问数据库的时候，是访问平行处理数据库。而不是访问ClusterDB或pgreplicateDB。

由平行数据库询问调度数据库，当前查询或修改使用那个节点。

节点收到平行数据库访问请求事务后，使用二阶段递交，因为每一个查询与修改都是一个事务，事务完成后发送信号到调度数据库。本次查询与修改递交完成。

调度数据库再通知别的节点数据库同步更改。同步节点完成后调度数据库再通知原节点数据库本次事务顺利完成。你可以把结果反回给客户端了。

在这样的一个集群里面我们不需要关心使用那个节点，节点之前怎样同步。
之所以这样推测，是想使大家有一个概念为什么要这样部署，有什么作用。
不能想当然而所以然。

上面讲得可能简单了一点。

但我想读完的朋友，应该会对postgresql集群数据库有一个基础的理论知识了。