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GreenPlum数据库Master节点Standby同步与切换

本文档主要演示GreenPlum数据库的Master节点的Standby在异常后的数据同步及Master节点故障后,Standby的切换。在操作前通过gpstate命令查看Standby的状态是正常的,数据也在同步状态。

[gpadmin@mdw ~]$ gpstate -f
20160227:17:00:24:019032 gpstate:mdw:gpadmin-[INFO]:-Starting gpstate with args: -f
20160227:17:00:24:019032 gpstate:mdw:gpadmin-[INFO]:-local Greenplum Version: 'postgres (Greenplum Database) 4.3.6.2 build 1'
20160227:17:00:24:019032 gpstate:mdw:gpadmin-[INFO]:-master Greenplum Version: 'PostgreSQL 8.2.15 (Greenplum Database 4.3.6.2 build 1) on x86_64-unknown-linux-gnu, compiled by GCC gcc (GCC) 4.4.2 compiled on Nov 12 2015 23:50:28'
20160227:17:00:24:019032 gpstate:mdw:gpadmin-[INFO]:-Obtaining Segment details from master...
20160227:17:00:24:019032 gpstate:mdw:gpadmin-[INFO]:-Standby master details
20160227:17:00:24:019032 gpstate:mdw:gpadmin-[INFO]:-----------------------
20160227:17:00:24:019032 gpstate:mdw:gpadmin-[INFO]:-   Standby address          = mdw-std
20160227:17:00:24:019032 gpstate:mdw:gpadmin-[INFO]:-   Standby data directory   = /gpdb/gpdata/master/gpseg-1
20160227:17:00:24:019032 gpstate:mdw:gpadmin-[INFO]:-   Standby port             = 5432
20160227:17:00:24:019032 gpstate:mdw:gpadmin-[INFO]:-   Standby PID              = 3139
20160227:17:00:24:019032 gpstate:mdw:gpadmin-[INFO]:-   Standby status           = Standby host passive
20160227:17:00:24:019032 gpstate:mdw:gpadmin-[INFO]:-----------------------------------------
20160227:17:00:24:019032 gpstate:mdw:gpadmin-[INFO]:--pg_stat_replication
20160227:17:00:24:019032 gpstate:mdw:gpadmin-[INFO]:-----------------------------------------
20160227:17:00:24:019032 gpstate:mdw:gpadmin-[INFO]:--WAL Sender State: streaming
20160227:17:00:24:019032 gpstate:mdw:gpadmin-[INFO]:--Sync state: sync
20160227:17:00:24:019032 gpstate:mdw:gpadmin-[INFO]:--Sent Location: 0/C203088
20160227:17:00:24:019032 gpstate:mdw:gpadmin-[INFO]:--Flush Location: 0/C203088
20160227:17:00:24:019032 gpstate:mdw:gpadmin-[INFO]:--Replay Location: 0/C203088
20160227:17:00:24:019032 gpstate:mdw:gpadmin-[INFO]:-----------------------------------------

然后直接关闭Standby所在的主机,模拟Standby故障,通过gpstate命令可以查看到Standby已经连接失败。

[gpadmin@mdw ~]$ gpstate -f
20160227:17:01:14:019099 gpstate:mdw:gpadmin-[INFO]:-Starting gpstate with args: -f
20160227:17:01:14:019099 gpstate:mdw:gpadmin-[INFO]:-local Greenplum Version: 'postgres (Greenplum Database) 4.3.6.2 build 1'
20160227:17:01:14:019099 gpstate:mdw:gpadmin-[INFO]:-master Greenplum Version: 'PostgreSQL 8.2.15 (Greenplum Database 4.3.6.2 build 1) on x86_64-unknown-linux-gnu, compiled by GCC gcc (GCC) 4.4.2 compiled on Nov 12 2015 23:50:28'
20160227:17:01:14:019099 gpstate:mdw:gpadmin-[INFO]:-Obtaining Segment details from master...
20160227:17:01:32:019099 gpstate:mdw:gpadmin-[INFO]:-Standby master details
20160227:17:01:32:019099 gpstate:mdw:gpadmin-[INFO]:-----------------------
20160227:17:01:32:019099 gpstate:mdw:gpadmin-[INFO]:-   Standby address          = mdw-std
20160227:17:01:32:019099 gpstate:mdw:gpadmin-[INFO]:-   Standby data directory   = /gpdb/gpdata/master/gpseg-1
20160227:17:01:32:019099 gpstate:mdw:gpadmin-[INFO]:-   Standby port             = 5432
20160227:17:01:32:019099 gpstate:mdw:gpadmin-[WARNING]:-Standby PID              = Error getting status from host mdw-std   <<<<<<<<
20160227:17:01:32:019099 gpstate:mdw:gpadmin-[WARNING]:-Standby status           = Status could not be determined           <<<<<<<<
20160227:17:01:32:019099 gpstate:mdw:gpadmin-[INFO]:-----------------------------------------
20160227:17:01:32:019099 gpstate:mdw:gpadmin-[INFO]:--pg_stat_replication
20160227:17:01:32:019099 gpstate:mdw:gpadmin-[INFO]:-----------------------------------------
20160227:17:01:32:019099 gpstate:mdw:gpadmin-[INFO]:--WAL Sender State: streaming
20160227:17:01:32:019099 gpstate:mdw:gpadmin-[INFO]:--Sync state: sync
20160227:17:01:32:019099 gpstate:mdw:gpadmin-[INFO]:--Sent Location: 0/C203088
20160227:17:01:32:019099 gpstate:mdw:gpadmin-[INFO]:--Flush Location: 0/C203088
20160227:17:01:32:019099 gpstate:mdw:gpadmin-[INFO]:--Replay Location: 0/C203088
20160227:17:01:32:019099 gpstate:mdw:gpadmin-[INFO]:-----------------------------------------

同路Master节点,创建一张表,模拟Master节点数据变化。

dbdream=> \c
You are now connected to database "dbdream" as user "dbdream".
dbdream=> \d
                     List of relations
 Schema |         Name         | Type  |  Owner  | Storage  
--------+----------------------+-------+---------+----------
 public | med_ord_pgm_d        | table | dbdream | heap
 public | med_ord_pgm_d_err    | table | gpadmin | heap
 public | med_ord_pgm_d_ext    | table | gpadmin | external
 public | med_ord_pgm_d_unload | table | gpadmin | external
 public | ord_pay              | table | dbdream | heap
 public | ord_pay_errs         | table | gpadmin | heap
(6 rows)

dbdream=> create table ord_pay_s(like ord_pay);
NOTICE:  Table doesn't have 'distributed by' clause, defaulting to distribution columns from LIKE table
CREATE TABLE
dbdream=> \d
                     List of relations
 Schema |         Name         | Type  |  Owner  | Storage  
--------+----------------------+-------+---------+----------
 public | med_ord_pgm_d        | table | dbdream | heap
 public | med_ord_pgm_d_err    | table | gpadmin | heap
 public | med_ord_pgm_d_ext    | table | gpadmin | external
 public | med_ord_pgm_d_unload | table | gpadmin | external
 public | ord_pay              | table | dbdream | heap
 public | ord_pay_errs         | table | gpadmin | heap
 public | ord_pay_s            | table | dbdream | heap
(7 rows)

启动Standby的主机,启动Standby,发现Standby已经自动同步了数据。

[gpadmin@mdw ~]$ gpstate -f
20160227:17:28:23:003476 gpstate:mdw:gpadmin-[INFO]:-Starting gpstate with args: -f
20160227:17:28:23:003476 gpstate:mdw:gpadmin-[INFO]:-local Greenplum Version: 'postgres (Greenplum Database) 4.3.6.2 build 1'
20160227:17:28:23:003476 gpstate:mdw:gpadmin-[INFO]:-master Greenplum Version: 'PostgreSQL 8.2.15 (Greenplum Database 4.3.6.2 build 1) on x86_64-unknown-linux-gnu, compiled by GCC gcc (GCC) 4.4.2 compiled on Nov 12 2015 23:50:28'
20160227:17:28:23:003476 gpstate:mdw:gpadmin-[INFO]:-Obtaining Segment details from master...
20160227:17:28:23:003476 gpstate:mdw:gpadmin-[INFO]:-Standby master details
20160227:17:28:23:003476 gpstate:mdw:gpadmin-[INFO]:-----------------------
20160227:17:28:23:003476 gpstate:mdw:gpadmin-[INFO]:-   Standby address          = mdw-std
20160227:17:28:23:003476 gpstate:mdw:gpadmin-[INFO]:-   Standby data directory   = /gpdb/gpdata/master/gpseg-1
20160227:17:28:23:003476 gpstate:mdw:gpadmin-[INFO]:-   Standby port             = 5432
20160227:17:28:23:003476 gpstate:mdw:gpadmin-[INFO]:-   Standby PID              = 3621
20160227:17:28:23:003476 gpstate:mdw:gpadmin-[INFO]:-   Standby status           = Standby host passive
20160227:17:28:23:003476 gpstate:mdw:gpadmin-[INFO]:--------------------------------------
20160227:17:28:23:003476 gpstate:mdw:gpadmin-[INFO]:--pg_stat_replication
20160227:17:28:23:003476 gpstate:mdw:gpadmin-[INFO]:--------------------------------------
20160227:17:28:23:003476 gpstate:mdw:gpadmin-[INFO]:--WAL Sender State: streaming
20160227:17:28:23:003476 gpstate:mdw:gpadmin-[INFO]:--Sync state: sync
20160227:17:28:23:003476 gpstate:mdw:gpadmin-[INFO]:--Sent Location: 0/C269D88
20160227:17:28:23:003476 gpstate:mdw:gpadmin-[INFO]:--Flush Location: 0/C269D88
20160227:17:28:23:003476 gpstate:mdw:gpadmin-[INFO]:--Replay Location: 0/C269D88
20160227:17:28:23:003476 gpstate:mdw:gpadmin-[INFO]:--------------------------------------

如果Standby数据不能自动同步,那么就需要重新初始化Standby的数据,也就是手动全量同步数据,因为Master只存数据库的元数据,通常都很小,这个过程很快即可完成,但是需要将Master数据库启动到Utility模式,否则会遇到下面的错误。

[gpadmin@mdw ~]$ gpinitstandby -n
20160227:17:17:52:002836 gpinitstandby:mdw:gpadmin-[INFO]:-Standy master is already up and running.

使用gpstart –m只将Master节点启动到Utility模式。

[gpadmin@mdw ~]$ gpstop –a

[gpadmin@mdw ~]$ gpstart -m
20160227:17:24:21:003056 gpstart:mdw:gpadmin-[INFO]:-Starting gpstart with args: -m
20160227:17:24:21:003056 gpstart:mdw:gpadmin-[INFO]:-Gathering information and validating the environment...
20160227:17:24:21:003056 gpstart:mdw:gpadmin-[INFO]:-Greenplum Binary Version: 'postgres (Greenplum Database) 4.3.6.2 build 1'
20160227:17:24:21:003056 gpstart:mdw:gpadmin-[INFO]:-Greenplum Catalog Version: '201310150'
20160227:17:24:21:003056 gpstart:mdw:gpadmin-[WARNING]:-****************************************
20160227:17:24:21:003056 gpstart:mdw:gpadmin-[WARNING]:-Master-only start requested in a configuration with a standby master.
20160227:17:24:21:003056 gpstart:mdw:gpadmin-[WARNING]:-This is advisable only under the direct supervision of Greenplum support. 
20160227:17:24:21:003056 gpstart:mdw:gpadmin-[WARNING]:-This mode of operation is not supported in a production environment and 
20160227:17:24:21:003056 gpstart:mdw:gpadmin-[WARNING]:-may lead to a split-brain condition and possible unrecoverable data loss.
20160227:17:24:21:003056 gpstart:mdw:gpadmin-[WARNING]:-*************************************

Continue with master-only startup Yy|Nn (default=N):

此处需要输入Y确认。

> y
20160227:17:24:23:003056 gpstart:mdw:gpadmin-[INFO]:-Starting Master instance in admin mode
20160227:17:24:24:003056 gpstart:mdw:gpadmin-[INFO]:-Obtaining Greenplum Master catalog information
20160227:17:24:24:003056 gpstart:mdw:gpadmin-[INFO]:-Obtaining Segment details from master...
20160227:17:24:24:003056 gpstart:mdw:gpadmin-[INFO]:-Setting new master era
20160227:17:24:24:003056 gpstart:mdw:gpadmin-[INFO]:-Master Started...

将Master启动到Utility模式后,使用gpinitstandby来重新初始化Standby的数据。

[gpadmin@mdw ~]$ gpinitstandby -n
20160227:17:24:49:003161 gpinitstandby:mdw:gpadmin-[INFO]:-Starting standby master
20160227:17:24:49:003161 gpinitstandby:mdw:gpadmin-[INFO]:-Checking if standby master is running on host: mdw-std  in directory: /gpdb/gpdata/master/gpseg-1
20160227:17:24:50:003161 gpinitstandby:mdw:gpadmin-[INFO]:-Successfully started standby master

重启数据库,Standby的状态就会正常。

[gpadmin@mdw ~]$ gpstop –a
[gpadmin@mdw ~]$ gpstart –a
[gpadmin@mdw ~]$ gpstate -f
20160227:17:28:23:003476 gpstate:mdw:gpadmin-[INFO]:-Starting gpstate with args: -f
20160227:17:28:23:003476 gpstate:mdw:gpadmin-[INFO]:-local Greenplum Version: 'postgres (Greenplum Database) 4.3.6.2 build 1'
20160227:17:28:23:003476 gpstate:mdw:gpadmin-[INFO]:-master Greenplum Version: 'PostgreSQL 8.2.15 (Greenplum Database 4.3.6.2 build 1) on x86_64-unknown-linux-gnu, compiled by GCC gcc (GCC) 4.4.2 compiled on Nov 12 2015 23:50:28'
20160227:17:28:23:003476 gpstate:mdw:gpadmin-[INFO]:-Obtaining Segment details from master...
20160227:17:28:23:003476 gpstate:mdw:gpadmin-[INFO]:-Standby master details
20160227:17:28:23:003476 gpstate:mdw:gpadmin-[INFO]:-----------------------
20160227:17:28:23:003476 gpstate:mdw:gpadmin-[INFO]:-   Standby address          = mdw-std
20160227:17:28:23:003476 gpstate:mdw:gpadmin-[INFO]:-   Standby data directory   = /gpdb/gpdata/master/gpseg-1
20160227:17:28:23:003476 gpstate:mdw:gpadmin-[INFO]:-   Standby port             = 5432
20160227:17:28:23:003476 gpstate:mdw:gpadmin-[INFO]:-   Standby PID              = 3621
20160227:17:28:23:003476 gpstate:mdw:gpadmin-[INFO]:-   Standby status           = Standby host passive
20160227:17:28:23:003476 gpstate:mdw:gpadmin-[INFO]:-----------------------------------------
20160227:17:28:23:003476 gpstate:mdw:gpadmin-[INFO]:--pg_stat_replication
20160227:17:28:23:003476 gpstate:mdw:gpadmin-[INFO]:-----------------------------------------
 20160227:17:28:23:003476 gpstate:mdw:gpadmin-[INFO]:--WAL Sender State: streaming
20160227:17:28:23:003476 gpstate:mdw:gpadmin-[INFO]:--Sync state: sync
20160227:17:28:23:003476 gpstate:mdw:gpadmin-[INFO]:--Sent Location: 0/C269D88
20160227:17:28:23:003476 gpstate:mdw:gpadmin-[INFO]:--Flush Location: 0/C269D88
20160227:17:28:23:003476 gpstate:mdw:gpadmin-[INFO]:--Replay Location: 0/C269D88
20160227:17:28:23:003476 gpstate:mdw:gpadmin-[INFO]:-----------------------------------------

下面模拟Master节点故障,切换到Standby的情况。直接关闭Master节点主机的电源,模拟Master节点故障。可以通过gpactivatestandby命令将Standby切换成Master,这个命令依赖几个环境变量,下面的测试会一一介绍。

MASTER_DATA_DIRECTORY环境变量,在切换Standby时,必须设置MASTER_DATA_DIRECTORY环境变量,直接在命令后面写上直接路径也是不行的,如下:

[gpadmin@mdw-std ~]$ gpactivatestandby -d /gpdb/gpdata/master/gpseg-1
20160227:17:33:04:003762 gpactivatestandby:mdw-std:gpadmin-[CRITICAL]:-MASTER_DATA_DIRECTORY environment variable not set.
[gpadmin@mdw-std ~]$ gpactivatestandby -d /gpdb/gpdata/master/gpseg-1
20160227:17:33:42:003781 gpactivatestandby:mdw-std:gpadmin-[CRITICAL]:-MASTER_DATA_DIRECTORY environment variable not set.

编辑profile文件,增加MASTER_DATA_DIRECTORY环境变量后使之生效。

[gpadmin@mdw-std ~]$ vi .bash_profile

source /gpdb/app/greenplum_path.sh
export MASTER_DATA_DIRECTORY=/gpdb/gpdata/master/gpseg-1
export PGDATABASE=dbdream

[gpadmin@mdw-std ~]$ . .bash_profile

PGPORT环境变量,同样也需要设置PGPORT环境变量。

[gpadmin@mdw-std ~]$ gpactivatestandby -d $MASTER_DATA_DIRECTORY
20160227:17:34:28:003809 gpactivatestandby:mdw-std:gpadmin-[CRITICAL]:-PGPORT environment variable not set.

编辑profile文件,增加PGPORT环境变量,使之生效。

[gpadmin@mdw-std ~]$ vi .bash_profile

source /gpdb/app/greenplum_path.sh
export MASTER_DATA_DIRECTORY=/gpdb/gpdata/master/gpseg-1
export PGDATABASE=dbdream
export PGPORT=5432

[gpadmin@mdw-std ~]$ . .bash_profile

此时即可切换Standby了。

[gpadmin@mdw-std ~]$ gpactivatestandby -d $MASTER_DATA_DIRECTORY
20160227:17:35:02:003839 gpactivatestandby:mdw-std:gpadmin-[INFO]:---------------------
20160227:17:35:02:003839 gpactivatestandby:mdw-std:gpadmin-[INFO]:-Standby data directory    = /gpdb/gpdata/master/gpseg-1
20160227:17:35:02:003839 gpactivatestandby:mdw-std:gpadmin-[INFO]:-Standby port              = 5432
20160227:17:35:02:003839 gpactivatestandby:mdw-std:gpadmin-[INFO]:-Standby running           = yes
20160227:17:35:02:003839 gpactivatestandby:mdw-std:gpadmin-[INFO]:-Force standby activation  = no
20160227:17:35:02:003839 gpactivatestandby:mdw-std:gpadmin-[INFO]:---------------------
Do you want to continue with standby master activation? Yy|Nn (default=N):

输入Y确定切换。

> y
20160227:17:35:04:003839 gpactivatestandby:mdw-std:gpadmin-[INFO]:-found standby postmaster process
20160227:17:35:04:003839 gpactivatestandby:mdw-std:gpadmin-[INFO]:-Updating transaction files filespace flat files...
20160227:17:35:04:003839 gpactivatestandby:mdw-std:gpadmin-[INFO]:-Updating temporary files filespace flat files...
20160227:17:35:04:003839 gpactivatestandby:mdw-std:gpadmin-[INFO]:-Promoting standby...
20160227:17:35:04:003839 gpactivatestandby:mdw-std:gpadmin-[DEBUG]:-Waiting for connection...
20160227:17:35:06:003839 gpactivatestandby:mdw-std:gpadmin-[INFO]:-Standby master is promoted
20160227:17:35:06:003839 gpactivatestandby:mdw-std:gpadmin-[INFO]:-Reading current configuration...
20160227:17:35:06:003839 gpactivatestandby:mdw-std:gpadmin-[DEBUG]:-Connecting to dbname=dbdream
20160227:17:35:06:003839 gpactivatestandby:mdw-std:gpadmin-[INFO]:-Writing the gp_dbid file - /gpdb/gpdata/master/gpseg-1/gp_dbid...
20160227:17:35:06:003839 gpactivatestandby:mdw-std:gpadmin-[INFO]:-But found an already existing file.
20160227:17:35:06:003839 gpactivatestandby:mdw-std:gpadmin-[INFO]:-Hence removed that existing file.
20160227:17:35:06:003839 gpactivatestandby:mdw-std:gpadmin-[INFO]:-Creating a new file...
20160227:17:35:06:003839 gpactivatestandby:mdw-std:gpadmin-[INFO]:-Wrote dbid: 1 to the file.
20160227:17:35:06:003839 gpactivatestandby:mdw-std:gpadmin-[INFO]:-Now marking it as read only...
20160227:17:35:06:003839 gpactivatestandby:mdw-std:gpadmin-[INFO]:-Verifying the file...
20160227:17:35:06:003839 gpactivatestandby:mdw-std:gpadmin-[INFO]:-------------------
20160227:17:35:06:003839 gpactivatestandby:mdw-std:gpadmin-[INFO]:-The activation of the standby master has completed successfully.
20160227:17:35:06:003839 gpactivatestandby:mdw-std:gpadmin-[INFO]:-mdw-std is now the new primary master.
20160227:17:35:06:003839 gpactivatestandby:mdw-std:gpadmin-[INFO]:-You will need to update your user access mechanism to reflect
20160227:17:35:06:003839 gpactivatestandby:mdw-std:gpadmin-[INFO]:-the change of master hostname.
20160227:17:35:06:003839 gpactivatestandby:mdw-std:gpadmin-[INFO]:-Do not re-start the failed master while the fail-over master is
20160227:17:35:06:003839 gpactivatestandby:mdw-std:gpadmin-[INFO]:-operational, this could result in database corruption!
20160227:17:35:06:003839 gpactivatestandby:mdw-std:gpadmin-[INFO]:-MASTER_DATA_DIRECTORY is now /gpdb/gpdata/master/gpseg-1 if
20160227:17:35:06:003839 gpactivatestandby:mdw-std:gpadmin-[INFO]:-this has changed as a result of the standby master activation, remember
20160227:17:35:06:003839 gpactivatestandby:mdw-std:gpadmin-[INFO]:-to change this in any startup scripts etc, that may be configured
20160227:17:35:06:003839 gpactivatestandby:mdw-std:gpadmin-[INFO]:-to set this value.
20160227:17:35:06:003839 gpactivatestandby:mdw-std:gpadmin-[INFO]:-MASTER_PORT is now 5432, if this has changed, you
20160227:17:35:06:003839 gpactivatestandby:mdw-std:gpadmin-[INFO]:-may need to make additional configuration changes to allow access
20160227:17:35:06:003839 gpactivatestandby:mdw-std:gpadmin-[INFO]:-to the Greenplum instance.
20160227:17:35:06:003839 gpactivatestandby:mdw-std:gpadmin-[INFO]:-Refer to the Administrator Guide for instructions on how to re-activate
20160227:17:35:06:003839 gpactivatestandby:mdw-std:gpadmin-[INFO]:-the master to its previous state once it becomes available.
20160227:17:35:06:003839 gpactivatestandby:mdw-std:gpadmin-[INFO]:-Query planner statistics must be updated on all databases
20160227:17:35:06:003839 gpactivatestandby:mdw-std:gpadmin-[INFO]:-following standby master activation.
20160227:17:35:06:003839 gpactivatestandby:mdw-std:gpadmin-[INFO]:-When convenient, run ANALYZE against all user databases.
20160227:17:35:06:003839 gpactivatestandby:mdw-std:gpadmin-[INFO]:-----------------------

切换完成,查看数据库的状态。

[gpadmin@mdw-std ~]$ gpstate -s
20160227:17:36:33:003954 gpstate:mdw-std:gpadmin-[INFO]:-Starting gpstate with args: -s
20160227:17:36:33:003954 gpstate:mdw-std:gpadmin-[INFO]:-local Greenplum Version: 'postgres (Greenplum Database) 4.3.6.2 build 1'
20160227:17:36:33:003954 gpstate:mdw-std:gpadmin-[INFO]:-master Greenplum Version: 'PostgreSQL 8.2.15 (Greenplum Database 4.3.6.2 build 1) on x86_64-unknown-linux-gnu, compiled by GCC gcc (GCC) 4.4.2 compiled on Nov 12 2015 23:50:28'
20160227:17:36:33:003954 gpstate:mdw-std:gpadmin-[INFO]:-Obtaining Segment details from master...
20160227:17:36:33:003954 gpstate:mdw-std:gpadmin-[INFO]:-Gathering data from segments...
. 
20160227:17:36:34:003954 gpstate:mdw-std:gpadmin-[INFO]:-----------------------------------------------------
20160227:17:36:34:003954 gpstate:mdw-std:gpadmin-[INFO]:--Master Configuration & Status
20160227:17:36:34:003954 gpstate:mdw-std:gpadmin-[INFO]:-----------------------------------------------------
20160227:17:36:34:003954 gpstate:mdw-std:gpadmin-[INFO]:-   Master host                    = mdw-std
20160227:17:36:34:003954 gpstate:mdw-std:gpadmin-[INFO]:-   Master postgres process ID     = 3621
20160227:17:36:34:003954 gpstate:mdw-std:gpadmin-[INFO]:-   Master data directory          = /gpdb/gpdata/master/gpseg-1
20160227:17:36:34:003954 gpstate:mdw-std:gpadmin-[INFO]:-   Master port                    = 5432
20160227:17:36:34:003954 gpstate:mdw-std:gpadmin-[INFO]:-   Master current role            = dispatch
20160227:17:36:34:003954 gpstate:mdw-std:gpadmin-[INFO]:-   Greenplum initsystem version   = 4.3.6.2 build 1
20160227:17:36:34:003954 gpstate:mdw-std:gpadmin-[INFO]:-   Greenplum current version      = PostgreSQL 8.2.15 (Greenplum Database 4.3.6.2 build 1) on x86_64-unknown-linux-gnu, compiled by GCC gcc (GCC) 4.4.2 compiled on Nov 12 2015 23:50:28
20160227:17:36:34:003954 gpstate:mdw-std:gpadmin-[INFO]:-   Postgres version               = 8.2.15
20160227:17:36:34:003954 gpstate:mdw-std:gpadmin-[INFO]:-   Master standby                 = No master standby configured
20160227:17:36:34:003954 gpstate:mdw-std:gpadmin-[INFO]:---------------------------------
20160227:17:36:34:003954 gpstate:mdw-std:gpadmin-[INFO]:-Segment Instance Status Report
20160227:17:36:34:003954 gpstate:mdw-std:gpadmin-[INFO]:---------------------------------
20160227:17:36:34:003954 gpstate:mdw-std:gpadmin-[INFO]:-   Segment Info
20160227:17:36:34:003954 gpstate:mdw-std:gpadmin-[INFO]:-      Hostname                          = sdw1
20160227:17:36:34:003954 gpstate:mdw-std:gpadmin-[INFO]:-      Address                           = sdw1
20160227:17:36:34:003954 gpstate:mdw-std:gpadmin-[INFO]:-      Datadir                           = /gpdb/gpdata/primary/gpseg0
20160227:17:36:34:003954 gpstate:mdw-std:gpadmin-[INFO]:-      Port                              = 40000
20160227:17:36:34:003954 gpstate:mdw-std:gpadmin-[INFO]:-   Status
20160227:17:36:34:003954 gpstate:mdw-std:gpadmin-[INFO]:-      PID                               = 2670
20160227:17:36:34:003954 gpstate:mdw-std:gpadmin-[INFO]:-      Configuration reports status as   = Up
20160227:17:36:34:003954 gpstate:mdw-std:gpadmin-[INFO]:-      Database status                   = Up
20160227:17:36:34:003954 gpstate:mdw-std:gpadmin-[INFO]:---------------------------
20160227:17:36:34:003954 gpstate:mdw-std:gpadmin-[INFO]:-   Segment Info
20160227:17:36:34:003954 gpstate:mdw-std:gpadmin-[INFO]:-      Hostname                          = sdw2
20160227:17:36:34:003954 gpstate:mdw-std:gpadmin-[INFO]:-      Address                           = sdw2
20160227:17:36:34:003954 gpstate:mdw-std:gpadmin-[INFO]:-      Datadir                           = /gpdb/gpdata/primary/gpseg1
20160227:17:36:34:003954 gpstate:mdw-std:gpadmin-[INFO]:-      Port                              = 40000
20160227:17:36:34:003954 gpstate:mdw-std:gpadmin-[INFO]:-   Status
20160227:17:36:34:003954 gpstate:mdw-std:gpadmin-[INFO]:-      PID                               = 2431
20160227:17:36:34:003954 gpstate:mdw-std:gpadmin-[INFO]:-      Configuration reports status as   = Up
20160227:17:36:34:003954 gpstate:mdw-std:gpadmin-[INFO]:-      Database status                   = Up
20160227:17:36:34:003954 gpstate:mdw-std:gpadmin-[INFO]:---------------------------
20160227:17:36:34:003954 gpstate:mdw-std:gpadmin-[INFO]:-   Segment Info
20160227:17:36:34:003954 gpstate:mdw-std:gpadmin-[INFO]:-      Hostname                          = sdw3
20160227:17:36:34:003954 gpstate:mdw-std:gpadmin-[INFO]:-      Address                           = sdw3
20160227:17:36:34:003954 gpstate:mdw-std:gpadmin-[INFO]:-      Datadir                           = /gpdb/gpdata/primary/gpseg2
20160227:17:36:34:003954 gpstate:mdw-std:gpadmin-[INFO]:-      Port                              = 40000
20160227:17:36:34:003954 gpstate:mdw-std:gpadmin-[INFO]:-   Status
20160227:17:36:34:003954 gpstate:mdw-std:gpadmin-[INFO]:-      PID                               = 4427
20160227:17:36:34:003954 gpstate:mdw-std:gpadmin-[INFO]:-      Configuration reports status as   = Up
20160227:17:36:34:003954 gpstate:mdw-std:gpadmin-[INFO]:-      Database status                   = Up

此时Standby已经切换成Master,原因的Master节点已经被踢出了集群,切换后的数据库显示的是No master standby configured状态,通过gpstate –f参数也可以看到新的集群已经没有了Standby,Standby状态变成了Standby master instance not configured状态。

[gpadmin@mdw-std ~]$ gpstate -f
20160301:16:29:07:022510 gpstate:mdw-std:gpadmin-[INFO]:-Starting gpstate with args: -f
20160301:16:29:07:022510 gpstate:mdw-std:gpadmin-[INFO]:-local Greenplum Version: 'postgres (Greenplum Database) 4.3.6.2 build 1'
20160301:16:29:07:022510 gpstate:mdw-std:gpadmin-[INFO]:-master Greenplum Version: 'PostgreSQL 8.2.15 (Greenplum Database 4.3.6.2 build 1) on x86_64-unknown-linux-gnu, compiled by GCC gcc (GCC) 4.4.2 compiled on Nov 12 2015 23:50:28'
20160301:16:29:07:022510 gpstate:mdw-std:gpadmin-[INFO]:-Obtaining Segment details from master...
20160301:16:29:07:022510 gpstate:mdw-std:gpadmin-[INFO]:-Standby master instance not configured
20160301:16:29:07:022510 gpstate:mdw-std:gpadmin-[INFO]:-------------------------
20160301:16:29:07:022510 gpstate:mdw-std:gpadmin-[INFO]:--pg_stat_replication
20160301:16:29:07:022510 gpstate:mdw-std:gpadmin-[INFO]:-------------------------
20160301:16:29:07:022510 gpstate:mdw-std:gpadmin-[INFO]:-No entries found.
20160301:16:29:07:022510 gpstate:mdw-std:gpadmin-[INFO]:-------------------------

也就是gpactivatestandby切换相当于ORACLE的failover。登录到数据库,查询gp_segment_configuration基础表也可以看出源Master已经被踢出了集群,Standby已经变成了新的Master。

[gpadmin@mdw-std ~]$ psql 
psql (8.2.15)
Type "help" for help.

dbdream=# select * from gp_segment_configuration;
 dbid | content | role | preferred_role | mode | status | port  | hostname | address | replication_port | san_mounts 
------+---------+------+----------------+------+--------+-------+----------+---------+------------------+--------
    2 |       0 | p    | p              | s    | u      | 40000 | sdw1     | sdw1    |                  | 
    3 |       1 | p    | p              | s    | u      | 40000 | sdw2     | sdw2    |                  | 
    4 |       2 | p    | p              | s    | u      | 40000 | sdw3     | sdw3    |                  | 
    1 |      -1 | p    | p              | s    | u      |  5432 | mdw-std  | mdw-std |                  | 
(4 rows)

下面查看下,在切换之前建的那张表是否可以查询到。

dbdream=# \d
                     List of relations
 Schema |         Name         | Type  |  Owner  | Storage  
--------+----------------------+-------+---------+----------
 public | med_ord_pgm_d        | table | dbdream | heap
 public | med_ord_pgm_d_err    | table | gpadmin | heap
 public | med_ord_pgm_d_ext    | table | gpadmin | external
 public | med_ord_pgm_d_unload | table | gpadmin | external
 public | ord_pay              | table | dbdream | heap
 public | ord_pay_errs         | table | gpadmin | heap
 public | ord_pay_s            | table | dbdream | heap
(7 rows)

在切换前创建的ord_pay_s表可以查到,切换后,如果要访问数据库,需要连接Standby主机的IP地址,源Master已经被踢出了集群环境。

如果还要使用源Master节点的主机做Master,需要在源Master主机上搭建新Master的Standby,然后再切换回去即可。

本文固定链接: http://www.dbdream.com.cn/2016/03/greenplum%e6%95%b0%e6%8d%ae%e5%ba%93master%e8%8a%82%e7%82%b9standby%e5%90%8c%e6%ad%a5%e4%b8%8e%e5%88%87%e6%8d%a2/ | 信春哥,系统稳,闭眼上线不回滚!

该日志由 dbdream 于2016年03月01日发表在 GreenPlum 分类下, 你可以发表评论,并在保留原文地址及作者的情况下引用到你的网站或博客。
原创文章转载请注明: GreenPlum数据库Master节点Standby同步与切换 | 信春哥,系统稳,闭眼上线不回滚!
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