postgres-XL集群安裝

postgres-xl是個好東西？為什么呢？

postgres-xl基于postgresql數據庫, postgres可以吊打很多數據庫.

1. 它可以搞oltp, 抗衡mysql, mysql沒有分析函數功能

2. 它可以搞oltp, 抗衡oracle, oracle生態弱, 沒法實時

3. 它對json支持好, 抗衡mongodb, mongodb用得人越來越少了。。。

4. 它還恐怖地支持各種語言擴展, java, javascript, r, python, haskell。。。

5. 并且開源免費，簡單強大的沒朋友。。。

postgres-xl是postgresql MPP集群版, 繼續吊打大數據數據庫...

1. 它比greenpulm版本新: 它跟greenpulm本是一家人，都是MPP架構的postgresql集群
   但是原生改造, 版本基本上與postgresql一致, greenpulm的版本升不動啊。。。

2. 它比oracle RAC/Teradata便宜，免費使用

3. 它比hadoop省資源，沒有GC，基于C語言資源利用率高，并且生態圈豐富，可視化方便

4. 它出道早，版本穩定性強。

既然這么優秀，那么我們簡單介紹一下,尤其是它在大數據方面的應用

postgres-xl分為以下組件:
a. gtm 負責全局事務
b. coordinator 處理分發執行
c. datanode 負責底層處理

datanode跟coordinator都 連接到gtm，
客戶端連接到coordinator運行sql,
coordinator使用gtm進行一些事務功能分發給datanode執行

大數據的發展方向

什么是MPP？

MPP (Massively Parallel Processing)，即大規模并行處理，是分布式、并行、結構化數據庫集群，具備高性能、高可用、高擴展特性，可以為超大規模數據管理提供高性價比的通用計算平臺，廣泛用于支撐各類數據倉庫系統、BI 系統。

MPP架構特征：

?任務并行執行?

?數據分布式存儲(本地化)?

?分布式計算?

?橫向擴展

思考對比

Oracle集群的特點：每個節點全量存儲

Mysql熱備的特點：主從，每個節點全量存儲

MPP——分布式關系數據庫

GreenPlum：基于Postgres XL 8.2進行封裝，多年沒升級過。

Mysql Cluster：剛出來兩年，穩定性和性能比較差。

Postgres XL 與 Postgres LL ，是Postgresql數據庫兩種集群模式，Postgres XL是當今主流MPP

Postgres XL 集群架構

GTM：Global Transaction Manager

Coordinator：協調器

Datanode：數據節點

GTM-Proxy：GTM代理器

組件介紹

Global Transaction Monitor (GTM)

全局事務管理器，確保群集范圍內的事務一致性。 GTM負責發放事務ID和快照作為其多版本并發控制的一部分。

集群可選地配置一個備用GTM（GTM Standby），以改進可用性。此外，可以在協調器間配置代理GTM， 可用于改善可擴展性，減少GTM的通信量。

GTM Standby

GTM的備節點，在pgxc,pgxl中，GTM控制所有的全局事務分配，如果出現問題，就會導致整個集群不可用，為了增加可用性，增加該備用節點。當GTM出現問題時，GTM Standby可以升級為GTM，保證集群正常工作。

GTM-Proxy

GTM需要與所有的Coordinators通信，為了降低壓力，可以在每個Coordinator機器上部署一個GTM-Proxy。

Coordinator

協調員管理用戶會話，并與GTM和數據節點進行交互。協調員解析，產生查詢計劃，并給語句中的每一個組件發送下一個序列化的全局性計劃。

通常此服務和數據節點部署在一起。

正式安裝

Note: 其實在生產環境，如果你集群的數量少于20臺的話，甚至可以不需要使用gtm-proxy

#1)System?Initialization?Optimization?on?every?nodes

cat?>>?/etc/security/limits.conf?<<?EOF
*?hard?memlock?unlimited
*?soft?memlock?unlimited
*?-?nofile?65535
EOF

setenforce?0

sed?-i?'s/^SELINUX=.*$/SELINUX=disabled/'?/etc/selinux/config
?
systemctl?stop?firewalld.service
systemctl?disable?firewalld.service

cat?>/etc/hosts?<<EOF
172.31.1.81?neo4j01
172.31.4.146?neo4j02
172.31.3.178?neo4j03
172.31.8.178?neo4j04
EOF

#2)create?postgres?user?on?every?nodes

useradd?postgres
echo?Ad@sd119|passwd?--stdin?postgres
echo?'postgres?ALL=(ALL)?NOPASSWD:?ALL'?>>/etc/sudoers
######################################################################
#3)Configure?ssh?authentication?to?avoid?inputing?password?for?pgxc_ctl(run?this?commad?on?every?nodes)
######################################################################
su?-?postgres
ssh-keygen?-t?rsa???
cat?~/.ssh/id_rsa.pub?>>?~/.ssh/authorized_keys
chmod?600?authorized_keys
cat?~/.ssh/id_rsa.pub?|?ssh?neo4j01?'cat?>>?~/.ssh/authorized_keys'
############################################
#4)Install?dependency?packages?on?every?nodes#
############################################
sudo?yum?install?-y?flex?bison?readline-devel?zlib-devel?openjade?docbook-style-dsssl?gcc?bzip2?e2fsprogs-devel?uuid-devel?libuuid-devel?make?wget?
wget?-c?http://download.cashalo.com/schema/postgres-xl-9.5r1.6.tar.bz2?&&?tar?jxf?postgres-xl-9.5r1.6.tar.bz2
cd?postgres-xl-9.5r1.6
./configure?--prefix=/home/postgres/pgxl9.5?--with-uuid=ossp?--with-uuid=ossp?&&?make?&&?make?install?&&?cd?contrib/?&&?make?&&?make?install
?
#5)Configuring?environment?variables?on?every?nodes?

cat?>>/home/postgres/.bashrc?<<EOF
export?PGHOME=/home/postgres/pgxl9.5
export?LD_LIBRARY_PATH=\$PGHOME/lib:\$LD_LIBRARY_PATH
export?PATH=\$PGHOME/bin:\$PATH
EOF

source?/home/postgres/.bashrc

#6)create?data?dirsctory?on?every?nodes
mkdir?-p?/home/postgres/data/

#7)?just?run?command?pgxc_ctl?on?neo4j01
pgxc_ctl
#?then?input?command?prepare?
prepare
#?finally?run?q?to?exit?
q

#8)?Edit?file?pgxc_ctl.conf?(just?do?int?on?neo4j01)
vim?/home/postgres/pgxc_ctl/pgxc_ctl.conf
###########################################
#!/usr/bin/env?bash
pgxcInstallDir=/home/postgres/pgxl9.5
pgxlDATA=/home/postgres/data
#----?OVERALL?-----------------------------------------------------------------------------
#
pgxcOwner=postgres??????????????????????#?owner?of?the?Postgres-XC?databaseo?cluster.??Here,?we?use?this
????????????????????????????????????????????????#?both?as?linus?user?and?database?user.??This?must?be
????????????????????????????????????????????????#?the?super?user?of?each?coordinator?and?datanode.
pgxcUser=postgres???????????????#?OS?user?of?Postgres-XC?owner

tmpDir=/tmp?????????????????????????????????????#?temporary?dir?used?in?XC?servers
localTmpDir=$tmpDir?????????????????????#?temporary?dir?used?here?locally

configBackup=n??????????????????????????????????#?If?you?want?config?file?backup,?specify?y?to?this?value.
#configBackupHost=pgxc-linker???#?host?to?backup?config?file
#configBackupDir=$HOME/pgxc?????????????#?Backup?directory
#configBackupFile=pgxc_ctl.bak??#?Backup?file?name?-->?Need?to?synchronize?when?original?changed.

#----?GTM?------------------------------------------------------------------------------------

#?GTM?is?mandatory.??You?must?have?at?least?(and?only)?one?GTM?master?in?your?Postgres-XC?cluster.
#?If?GTM?crashes?and?you?need?to?reconfigure?it,?you?can?do?it?by?pgxc_update_gtm?command?to?update
#?GTM?master?with?others.???Of?course,?we?provide?pgxc_remove_gtm?command?to?remove?it.??This?command
#?will?not?stop?the?current?GTM.??It?is?up?to?the?operator.


#----?GTM?Master?-----------------------------------------------

#----?Overall?----
gtmName=gtm1
gtmMasterServer=neo4j01
gtmMasterPort=6666
gtmMasterDir=$pgxlDATA/gtm1

#----?Configuration?---
gtmExtraConfig=none?????????????????????#?Will?be?added?gtm.conf?for?both?Master?and?Slave?(done?at?initilization?only)
gtmMasterSpecificExtraConfig=none???????#?Will?be?added?to?Master's?gtm.conf?(done?at?initialization?only)

#----?GTM?Slave?-----------------------------------------------

#?Because?GTM?is?a?key?component?to?maintain?database?consistency,?you?may?want?to?configure?GTM?slave
#?for?backup.

#----?Overall?------
gtmSlave=y??????????????????????????????????????#?Specify?y?if?you?configure?GTM?Slave.???Otherwise,?GTM?slave?will?not?be?configured?and
????????????????????????????????????????????????????????#?all?the?following?variables?will?be?reset.
gtmSlaveName=gtm2
gtmSlaveServer=neo4j02??????????#?value?none?means?GTM?slave?is?not?available.??Give?none?if?you?don't?configure?GTM?Slave.
gtmSlavePort=6666???????????????????????#?Not?used?if?you?don't?configure?GTM?slave.
gtmSlaveDir=$pgxlDATA/gtm2??????#?Not?used?if?you?don't?configure?GTM?slave.
#?Please?note?that?when?you?have?GTM?failover,?then?there?will?be?no?slave?available?until?you?configure?the?slave
#?again.?(pgxc_add_gtm_slave?function?will?handle?it)

#----?Configuration?----
gtmSlaveSpecificExtraConfig=none?#?Will?be?added?to?Slave's?gtm.conf?(done?at?initialization?only)

#----?GTM?Proxy?-------------------------------------------------------------------------------------------------------
#?GTM?proxy?will?be?selected?based?upon?which?server?each?component?runs?on.
#?When?fails?over?to?the?slave,?the?slave?inherits?its?master's?gtm?proxy.??It?should?be
#?reconfigured?based?upon?the?new?location.
#
#?To?do?so,?slave?should?be?restarted.???So?pg_ctl?promote?->?(edit?postgresql.conf?and?recovery.conf)?->?pg_ctl?restart
#
#?You?don't?have?to?configure?GTM?Proxy?if?you?dont'?configure?GTM?slave?or?you?are?happy?if?every?component?connects
#?to?GTM?Master?directly.??If?you?configure?GTL?slave,?you?must?configure?GTM?proxy?too.

#----?Shortcuts?------
gtmProxyDir=$pgxlDATA/gtm_proxy

#----?Overall?-------
gtmProxy=n??????????????????????????????#?Specify?y?if?you?conifugre?at?least?one?GTM?proxy.???You?may?not?configure?gtm?proxies
????????????????????????????????????????????????#?only?when?you?dont'?configure?GTM?slaves.
????????????????????????????????????????????????#?If?you?specify?this?value?not?to?y,?the?following?parameters?will?be?set?to?default?empty?values.
????????????????????????????????????????????????#?If?we?find?there're?no?valid?Proxy?server?names?(means,?every?servers?are?specified
????????????????????????????????????????????????#?as?none),?then?gtmProxy?value?will?be?set?to?"n"?and?all?the?entries?will?be?set?to
????????????????????????????????????????????????#?empty?values.
#gtmProxyNames=(gtm_pxy1?gtm_pxy2?gtm_pxy3?gtm_pxy4)????#?No?used?if?it?is?not?configured
#gtmProxyServers=(neo4j01?neo4j02?neo4j03?neo4j04)??????????????????????#?Specify?none?if?you?dont'?configure?it.
#gtmProxyPorts=(6660?6666?6666?6666)????????????????????????????#?Not?used?if?it?is?not?configured.
#gtmProxyDirs=($gtmProxyDir?$gtmProxyDir?$gtmProxyDir?$gtmProxyDir)?????#?Not?used?if?it?is?not?configured.

#----?Configuration?----
gtmPxyExtraConfig=none??????????#?Extra?configuration?parameter?for?gtm_proxy.??Coordinator?section?has?an?example.
gtmPxySpecificExtraConfig=(none?none?none?none)

#----?Coordinators?----------------------------------------------------------------------------------------------------

#----?shortcuts?----------
coordMasterDir=$pgxlDATA/coord
coordSlaveDir=$pgxlDATA/coord_slave
coordArchLogDir=$pgxlDATA/coord_archlog

#----?Overall?------------
coordNames=(coord1?coord2?coord3?coord4)????????????????#?Master?and?slave?use?the?same?name
coordPorts=(5432?5432?5432?5432)????????????????????????#?Master?ports
poolerPorts=(6667?6667?6667?6667)???????????????????????#?Master?pooler?ports
#coordPgHbaEntries=(192.168.29.0/24)????????????????????????????#?Assumes?that?all?the?coordinator?(master/slave)?accepts
coordPgHbaEntries=(0.0.0.0/0)
????????????????????????????????????????????????????????????????????????????????????????????????#?the?same?connection
????????????????????????????????????????????????????????????????????????????????????????????????#?This?entry?allows?only?$pgxcOwner?to?connect.
????????????????????????????????????????????????????????????????????????????????????????????????#?If?you'd?like?to?setup?another?connection,?you?should
????????????????????????????????????????????????????????????????????????????????????????????????#?supply?these?entries?through?files?specified?below.
#?Note:?The?above?parameter?is?extracted?as?"host?all?all?0.0.0.0/0?trust".???If?you?don't?want
#?such?setups,?specify?the?value?()?to?this?variable?and?suplly?what?you?want?using?coordExtraPgHba
#?and/or?coordSpecificExtraPgHba?variables.
#coordPgHbaEntries=(::1/128)????#?Same?as?above?but?for?IPv6?addresses

#----?Master?-------------
coordMasterServers=(neo4j01?neo4j02?neo4j03?neo4j04)????????????#?none?means?this?master?is?not?available
coordMasterDirs=($coordMasterDir?$coordMasterDir?$coordMasterDir?$coordMasterDir)
coordMaxWALsernder=0????#?max_wal_senders:?needed?to?configure?slave.?If?zero?value?is?specified,
????????????????????????????????????????????????#?it?is?expected?to?supply?this?parameter?explicitly?by?external?files
????????????????????????????????????????????????#?specified?in?the?following.???If?you?don't?configure?slaves,?leave?this?value?to?zero.
coordMaxWALSenders=($coordMaxWALsernder?$coordMaxWALsernder?$coordMaxWALsernder?$coordMaxWALsernder)
????????????????????????????????????????????????#?max_wal_senders?configuration?for?each?coordinator.

#----?Slave?-------------
coordSlave=n????????????????????#?Specify?y?if?you?configure?at?least?one?coordiantor?slave.??Otherwise,?the?following
????????????????????????????????????????????????#?configuration?parameters?will?be?set?to?empty?values.
????????????????????????????????????????????????#?If?no?effective?server?names?are?found?(that?is,?every?servers?are?specified?as?none),
????????????????????????????????????????????????#?then?coordSlave?value?will?be?set?to?n?and?all?the?following?values?will?be?set?to
????????????????????????????????????????????????#?empty?values.
#coordSlaveSync=y???????????????#?Specify?to?connect?with?synchronized?mode.
#coordSlaveServers=(node07?node08?node09?node06)????????????????????????#?none?means?this?slave?is?not?available
#coordSlavePorts=(20004?20005?20004?20005)??????????????????????#?Master?ports
#coordSlavePoolerPorts=(20010?20011?20010?20011)????????????????????????#?Master?pooler?ports
#coordSlaveDirs=($coordSlaveDir?$coordSlaveDir?$coordSlaveDir?$coordSlaveDir)
#coordArchLogDirs=($coordArchLogDir?$coordArchLogDir?$coordArchLogDir?$coordArchLogDir)

#----?Configuration?files---
#?Need?these?when?you'd?like?setup?specific?non-default?configuration
#?These?files?will?go?to?corresponding?files?for?the?master.
#?You?may?supply?your?bash?script?to?setup?extra?config?lines?and?extra?pg_hba.conf?entries
#?Or?you?may?supply?these?files?manually.
coordExtraConfig=coordExtraConfig???????#?Extra?configuration?file?for?coordinators.
????????????????????????????????????????????????#?This?file?will?be?added?to?all?the?coordinators'
????????????????????????????????????????????????#?postgresql.conf
#?Pleae?note?that?the?following?sets?up?minimum?parameters?which?you?may?want?to?change.
#?You?can?put?your?postgresql.conf?lines?here.
cat?>?$coordExtraConfig?<<EOF
#================================================
#?Added?to?all?the?coordinator?postgresql.conf
#?Original:?$coordExtraConfig
log_destination?=?'stderr'
logging_collector?=?on
log_directory?=?'pg_log'
listen_addresses?=?'*'
max_connections?=?50
EOF

#?Additional?Configuration?file?for?specific?coordinator?master.
#?You?can?define?each?setting?by?similar?means?as?above.
coordSpecificExtraConfig=(none?none?none?none)
coordExtraPgHba=none????#?Extra?entry?for?pg_hba.conf.??This?file?will?be?added?to?all?the?coordinators'?pg_hba.conf
coordSpecificExtraPgHba=(none?none?none?none)

#-----?Additional?Slaves?-----
#
#?Please?note?that?this?section?is?just?a?suggestion?how?we?extend?the?configuration?for
#?multiple?and?cascaded?replication.???They're?not?used?in?the?current?version.
#
#coordAdditionalSlaves=n????????????????#?Additional?slave?can?be?specified?as?follows:?where?you
#coordAdditionalSlaveSet=(cad1)?????????#?Each?specifies?set?of?slaves.???This?case,?two?set?of?slaves?are
#???????????????????????????????????????????????????????????????????????????????????????#?configured
#cad1_Sync=n????????????????????????????#?All?the?slaves?at?"cad1"?are?connected?with?asynchronous?mode.
#???????????????????????????????????????????????????????#?If?not,?specify?"y"
#???????????????????????????????????????????????????????#?The?following?lines?specifies?detailed?configuration?for?each
#???????????????????????????????????????????????????????#?slave?tag,?cad1.??You?can?define?cad2?similarly.
#cad1_Servers=(node08?node09?node06?node07)?????#?Hosts
#cad1_dir=$HOME/pgxc/nodes/coord_slave_cad1
#cad1_Dirs=($cad1_dir?$cad1_dir?$cad1_dir?$cad1_dir)
#cad1_ArchLogDir=$HOME/pgxc/nodes/coord_archlog_cad1
#cad1_ArchLogDirs=($cad1_ArchLogDir?$cad1_ArchLogDir?$cad1_ArchLogDir?$cad1_ArchLogDir)


#----?Datanodes?-------------------------------------------------------------------------------------------------------

#----?Shortcuts?--------------
datanodeMasterDir=$pgxlDATA/dn_master
datanodeSlaveDir=$pgxlDATA/dn_slave
datanodeArchLogDir=$pgxlDATA/datanode_archlog

#----?Overall?---------------
#primaryDatanode=datanode1??????????????????????????????#?Primary?Node.
#?At?present,?xc?has?a?priblem?to?issue?ALTER?NODE?against?the?primay?node.??Until?it?is?fixed,?the?test?will?be?done
#?without?this?feature.
primaryDatanode=dn1?????????????????????????????#?Primary?Node.
datanodeNames=(dn1?dn2?dn3?dn4)
datanodePorts=(5433?5433?5433?5433)?????#?Master?ports
datanodePoolerPorts=(6668?6668?6668?6668)???????#?Master?pooler?ports
datanodePgHbaEntries=(0.0.0.0/0)????????#?Assumes?that?all?the?coordinator?(master/slave)?accepts
????????????????????????????????????????????????????????????????????????????????#?the?same?connection
????????????????????????????????????????????????????????????????????????????????#?This?list?sets?up?pg_hba.conf?for?$pgxcOwner?user.
????????????????????????????????????????????????????????????????????????????????#?If?you'd?like?to?setup?other?entries,?supply?them
????????????????????????????????????????????????????????????????????????????????#?through?extra?configuration?files?specified?below.
#?Note:?The?above?parameter?is?extracted?as?"host?all?all?0.0.0.0/0?trust".???If?you?don't?want
#?such?setups,?specify?the?value?()?to?this?variable?and?suplly?what?you?want?using?datanodeExtraPgHba
#?and/or?datanodeSpecificExtraPgHba?variables.
#datanodePgHbaEntries=(::1/128)?#?Same?as?above?but?for?IPv6?addresses

#----?Master?----------------
datanodeMasterServers=(neo4j01?neo4j02?neo4j03?neo4j04)?#?none?means?this?master?is?not?available.
????????????????????????????????????????????????????????????????????????????????????????????????????????#?This?means?that?there?should?be?the?master?but?is?down.
????????????????????????????????????????????????????????????????????????????????????????????????????????#?The?cluster?is?not?operational?until?the?master?is
????????????????????????????????????????????????????????????????????????????????????????????????????????#?recovered?and?ready?to?run.
datanodeMasterDirs=($datanodeMasterDir?$datanodeMasterDir?$datanodeMasterDir?$datanodeMasterDir)
datanodeMaxWalSender=0??????????????????????????????????????????????????????????#?max_wal_senders:?needed?to?configure?slave.?If?zero?value?is
????????????????????????????????????????????????????????????????????????????????????????????????????????#?specified,?it?is?expected?this?parameter?is?explicitly?supplied
????????????????????????????????????????????????????????????????????????????????????????????????????????#?by?external?configuration?files.
????????????????????????????????????????????????????????????????????????????????????????????????????????#?If?you?don't?configure?slaves,?leave?this?value?zero.
datanodeMaxWALSenders=($datanodeMaxWalSender?$datanodeMaxWalSender?$datanodeMaxWalSender?$datanodeMaxWalSender)
????????????????????????????????????????????????#?max_wal_senders?configuration?for?each?datanode

#----?Slave?-----------------
datanodeSlave=n?????????????????#?Specify?y?if?you?configure?at?least?one?coordiantor?slave.??Otherwise,?the?following
????????????????????????????????????????????????#?configuration?parameters?will?be?set?to?empty?values.
????????????????????????????????????????????????#?If?no?effective?server?names?are?found?(that?is,?every?servers?are?specified?as?none),
????????????????????????????????????????????????#?then?datanodeSlave?value?will?be?set?to?n?and?all?the?following?values?will?be?set?to
????????????????????????????????????????????????#?empty?values.
#datanodeSlaveServers=(node07?node08?node09?node06)?????#?value?none?means?this?slave?is?not?available
#datanodeSlavePorts=(20008?20009?20008?20009)???#?value?none?means?this?slave?is?not?available
#datanodeSlavePoolerPorts=(20012?20013?20012?20013)?????#?value?none?means?this?slave?is?not?available
#datanodeSlaveSync=y????????????#?If?datanode?slave?is?connected?in?synchronized?mode
#datanodeSlaveDirs=($datanodeSlaveDir?$datanodeSlaveDir?$datanodeSlaveDir?$datanodeSlaveDir)
#datanodeArchLogDirs=(?$datanodeArchLogDir?$datanodeArchLogDir?$datanodeArchLogDir?$datanodeArchLogDir?)

#?----?Configuration?files?---
#?You?may?supply?your?bash?script?to?setup?extra?config?lines?and?extra?pg_hba.conf?entries?here.
#?These?files?will?go?to?corresponding?files?for?the?master.
#?Or?you?may?supply?these?files?manually.
datanodeExtraConfig=none????????#?Extra?configuration?file?for?datanodes.??This?file?will?be?added?to?all?the
????????????????????????????????????????????????????????#?datanodes'?postgresql.conf
datanodeSpecificExtraConfig=(none?none?none?none)
datanodeExtraPgHba=none?????????#?Extra?entry?for?pg_hba.conf.??This?file?will?be?added?to?all?the?datanodes'?postgresql.conf
datanodeSpecificExtraPgHba=(none?none?none?none)

#-----?Additional?Slaves?-----
datanodeAdditionalSlaves=n??????#?Additional?slave?can?be?specified?as?follows:?where?you
#?datanodeAdditionalSlaveSet=(dad1?dad2)????????????????#?Each?specifies?set?of?slaves.???This?case,?two?set?of?slaves?are
????????????????????????????????????????????????????????????????????????????????????????#?configured
#?dad1_Sync=n???????????????????????????#?All?the?slaves?at?"cad1"?are?connected?with?asynchronous?mode.
????????????????????????????????????????????????????????#?If?not,?specify?"y"
????????????????????????????????????????????????????????#?The?following?lines?specifies?detailed?configuration?for?each
????????????????????????????????????????????????????????#?slave?tag,?cad1.??You?can?define?cad2?similarly.
#?dad1_Servers=(node08?node09?node06?node07)????#?Hosts
#?dad1_dir=$HOME/pgxc/nodes/coord_slave_cad1
#?dad1_Dirs=($cad1_dir?$cad1_dir?$cad1_dir?$cad1_dir)
#?dad1_ArchLogDir=$HOME/pgxc/nodes/coord_archlog_cad1
#?dad1_ArchLogDirs=($cad1_ArchLogDir?$cad1_ArchLogDir?$cad1_ArchLogDir?$cad1_ArchLogDir)

#----?WAL?archives?-------------------------------------------------------------------------------------------------
walArchive=n????#?If?you'd?like?to?configure?WAL?archive,?edit?this?section.
#######################################################
#8)?when?u?first?time?to?setup?cluster(run?it?just?on?neo4j01)
pgxc_ctl?-c?/home/postgres/pgxc_ctl/pgxc_ctl.conf?init?all?

#9)?start?cluster(run?it?just?on?neo4j01)
pgxc_ctl?-c?/home/postgres/pgxc_ctl/pgxc_ctl.conf?start?all
?
#10)?stop?cluster(run?it?just?on?neo4j01)
pgxc_ctl?-c?/home/postgres/pgxc_ctl/pgxc_ctl.conf?stop?all?

#11)?check?every?one?is?running(run?it?just?on?neo4j01)
pgxc_ctl
monitor?all

#12)?view?System?Table?(run?it?just?on?neo4j01)
psql?-p5432
select?*?from?pgxc_node;

postgres-XL 下存在兩種數據表，分別是replication表和distribute表

REPLICATION復制表：各個datanode節點中，表的數據完全相同，也就是說，插入數據時，會分別在每個datanode節點插入相同數據。讀數據時，只需要讀任意一個datanode節點上的數據。小表采用。

建表語法：

postgres=#?create?table?rep(col1?int,col2?int)distribute?by?replication;

DISTRIBUTE表 ：會將插入的數據，按照拆分規則，分配到不同的datanode節點中存儲，也就是sharding技術。每個datanode節點只保存了部分數據，通過coordinate節點可以查詢完整的數據視圖。分布式存儲，大表采用，默認

postgres=#??CREATE?TABLE?dist(col1?int,?col2?int)?DISTRIBUTE?BY?HASH(col1);

如何驗證分布式存儲？

分別插入100行數據：

postgres=#?INSERT?INTO?rep?SELECT?generate_series(1,100),?generate_series(101,?200);
postgres=#?INSERT?INTO?dist?SELECT?generate_series(1,100),?generate_series(101,?200);

psql -p 5432，通過Coordinater 訪問查詢完整的數據視圖；

psql -p 5433，5433是Datanode的端口，此時只訪問該單個節點

如何鏈接到指定的數據庫呢？看下面的例子

psql -p 5432 aa? ,aa為指定的庫名，不指定時默認是postgres庫，相當于hive里的default庫

查詢這個分布表數據在每個節點的分布：

postgres=#?SELECT?xc_node_id,?count(*)?FROM?dist?GROUP?BY?xc_node_id;
?xc_node_id?|?count
------------+-------
?-700122826?|????19
??352366662?|????27
?-560021589?|????23
??823103418?|????31
(4?rows)

查詢每個節點的ID信息

postgres=#?select?*?from?pgxc_node;

我們再來看看復制表

postgres=#?select?xc_node_id,count(*)?from?rep?group?by?xc_node_id;
?xc_node_id?|?count
------------+-------
?-560021589?|???100
(1?row)

因為我們是在neo4j01節點上查詢的，所以顯示的id就是neo4j01節點的id；同理，如果我們是在其它節點查詢的話那就顯示其它節點的id。也就是說當我們查詢復制表的時候，它只會走一個節點，不會走多個節點。針對這個特點，如果未來數據量很大，我們查詢的時候，可以走負載均衡。

https://www.cnblogs.com/sfnz/p/7908380.html

Psql是PostgreSQL的一個命令行交互式客戶端工具。PostgreSQL 一些命令、用法、語法，在Postgres xl集群都是通用的。