本节主要探讨greenplum集群配置和高可用特性。
目录：
- 配置greenplum数据库
- 启用高可用特性
基本概念：
raid | 独立硬盘冗余阵列（RAID, Redundant Array of Independent Disks） |
1.配置greenplum
Greenplum数据的配置文件postgresql.conf位于数据库实例的数据目录之下。
代码语言：javascript复制[gpadmin@gp-master etc]$ cd /data/master/gpseg-1/
[gpadmin@gp-master gpseg-1]$ ls
base gpmetrics pg_changetracking pg_distributedxidmap pg_log pg_subtrans pg_utilitymodedtmredo postgresql.conf
global gpperfmon pg_clog pg_hba.conf pg_multixact pg_tblspc PG_VERSION postmaster.opts
gp_dbid gpssh.conf pg_distributedlog pg_ident.conf pg_stat_tmp pg_twophase pg_xlog postmaster.pid- 设置本地参数
gpconfig，通过主节点就可以对所有节点的参数文件进行批量修改
代码语言：javascript复制[gpadmin@gp-master gpseg-1]$ gpconfig -s max_connections
Values on all segments are consistent
GUC : max_connections
Master value: 250
Segment value: 750[gpadmin@gp-master gpseg-1]$ gpconfig -c max_connections -v 750 -m 150
20191224:16:40:01:031503 gpconfig:gp-master:gpadmin-[INFO]:-completed successfully with parameters '-c max_connections -v 750 -m 150'[gpadmin@gp-master gpseg-1]$ gpstop -r
20191224:16:43:33:032280 gpstop:gp-master:gpadmin-[INFO]:-Starting gpstop with args: -r
20191224:16:43:33:032280 gpstop:gp-master:gpadmin-[INFO]:-Gathering information and validating the environment...
20191224:16:43:33:032280 gpstop:gp-master:gpadmin-[INFO]:-Obtaining Greenplum Master catalog information
20191224:16:43:33:032280 gpstop:gp-master:gpadmin-[INFO]:-Obtaining Segment details from master...
20191224:16:43:33:032280 gpstop:gp-master:gpadmin-[INFO]:-Greenplum Version: 'postgres (Greenplum Database) 5.21.1 build commit:ca0b8106b893028d18f241dcb858d85f12af90b6'[gpadmin@gp-master gpseg-1]$ gpconfig -s max_connections
Values on all segments are consistent
GUC : max_connections
Master value: 150
Segment value: 750案例：
gpconfig只能在系统启动的情况下调用，所以如果参数修改不合适，导致系统无法启动时，我们可以用下列方法处理：
1、先把master的参数修改成正常的值
2、gpstart -m 仅启动master进入管理模式
3、gpconfig -r <参数> -- 把参数重置成默认值
4、gpstop -a -r -M fast
- 设置master参数
编辑$MASTER_DATA_DIRECTORY/postgresql.conf文件，找到要设置的参数，取消它的注释（移除前面的#字符），并且输入想要的值。保存并且关闭该文件。
代码语言：javascript复制[gpadmin@gp-master gpseg-1]$ pwd
/data/master/gpseg-1
[gpadmin@gp-master gpseg-1]$ ls
base gpperfmon pg_distributedlog pg_log pg_tblspc pg_xlog postmaster.pid
global gpssh.conf pg_distributedxidmap pg_multixact pg_twophase postgresql.conf
gp_dbid pg_changetracking pg_hba.conf pg_stat_tmp pg_utilitymodedtmredo postgresql.conf.bak
gpmetrics pg_clog pg_ident.conf pg_subtrans PG_VERSION postmaster.opts需要重启生效的参数：
代码语言：javascript复制 gpstop -r不需要重启的参数：
代码语言：javascript复制gpstop -u - 在数据库级别设置参数
每一个连接到该数据库的会话都使用该参数设置。数据库级别的设置覆盖系统级别的设置。
代码语言：javascript复制=# ALTER DATABASE mydatabase SET search_path TO myschema;- 在角色级别设置参数
每一个由该角色启动的会话都使用该参数设置。角色级别的设置覆盖数据库级别的设置。
代码语言：javascript复制=# ALTER ROLE bob SET search_path TO bobschema;- 会话级别设置参数
=# SET statement_mem TO '200MB';=# RESET statement_mem;- 查看服务器配置参数
[gpadmin@gp-master gpseg-1]$ psql -c 'show all' -d postgres //查看master实例参数
name | setting
| description
------------------------------------------------------ ---------------------------------------------------------------------------
------- --------------------------------------------------------------------------------------------------------------------------
--------------------------------------------------------
add_missing_from | off
| Automatically adds missing table references to FROM clauses.
application_name | psql
| Sets the application name to be reported in statistics and logs.
archive_mode | off
| Allows archiving of WAL files using archive_command.
array_nulls | on[gpadmin@gp-master gpseg-1]$ gpconfig --show max_connections //查看全局参数
Values on all segments are consistent
GUC : max_connections
Master value: 150
Segment value: 750- 配置参数种类
连接和认证参数：
这些参数控制着客户端如何连接到Greenplum数据库以及如何被认证。
gp_connection_send_timeout
gp_vmem_idle_resource_timeout
listen_addresses
max_connections
max_prepared_transactions
superuser_reserved_connections
tcp_keepalives_count
tcp_keepalives_idle
tcp_keepalives_interval
unix_socket_directory
unix_socket_group
unix_socket_permissions
安全性和认证参数：
authentication_timeout
db_user_namespace
krb_caseins_users
krb_server_keyfile
krb_srvname
password_encryption
password_hash_algorithm
ssl
ssl_ciphers
2.启用高可用特性
- 硬件raid
从硬件存储级别实现的数据冗余。常用raid：
RAID0，RAID1，RAID5，RAID10
常见raid比对- segment镜像
Segment 分为主备，称为 Primary 和 Mirror，Mirror 是 Primary 的备。Primary与Mirror之间强同步保证数据一致性和可靠性，其间的监控与切换则由Master的FTS模块负责。当FTS发现Primary宕机、Mirror健康后会激活Mirror，并标记Primary为’d’，Mirror进入 ChangeTracking 状态。
- master镜像概述
由于Master不保存用户数据，只有系统目录表被在主Master和后备Master之间同步。当这些表被更新时，更改会被自动地复制到后备Master来让它保持与主Master的同步。
- 故障检测与修复概述
Greenplum数据库服务器名为ftsprobe的（postgres）子进程处理故障检测。ftsprobe会监控Greenplum数据库阵列，它连接并且扫描所有的Segment，并且数据库会按照配置的间隔进行这种处理。
gprecoverseg恢复工具。这个工具定位失效的Segment、验证它们是否有效并且与当前活动的Segment比较事务状态来确定该Segment离线期间所作的更改
代码语言：javascript复制[gpadmin@gp-master ~]$ gprecoverseg --help
COMMAND NAME: gprecoverseg
Recovers a primary or mirror segment instance that has //修复被标记为down的segment
been marked as down (if mirroring is enabled).
******************************************************
-i
主要参数，用于指定一个配置文件，该配置文件描述了需要修复的Segment和修复后的目的位置。
-F
可选项，指定后，gprecoverseg会将”-i”中指定的或标记”d”的实例删除，并从活着的Mirror复制一个完整一份到目标位置。
-r
当FTS发现有Primary宕机并进行主备切换，在gprecoverseg修复后，担当Primary的Mirror角色并不会立即切换回来，就会导致部分主机上活跃的Segment过多从而引起性能瓶颈。因此需要恢复Segment原先的角色，称为re-balance。
- 启用segment镜像 （此工具内容较多后续补充）
[gpadmin@gp-master ~]$ gpaddmirrors --help
COMMAND NAME: gpaddmirrors
Adds mirror segments to a Greenplum Database system that was
initially configured without mirroring.
*****************************************************
SYNOPSIS
*****************************************************
gpaddmirrors [-p <port_offset>] [-m <datadir_config_file> [-a]] [-s]
[-d <master_data_directory>] [-B <parallel_processes>]
[-l <logfile_directory>] [-v]
gpaddmirrors -i <mirror_config_file> [-s] [-a]
[-d <master_data_directory>] [-B <parallel_processes>]
[-l <logfile_directory>] [-v]
gpaddmirrors -o <output_sample_mirror_config> [-m <datadir_config_file>]
gpaddmirrors -?- 启用备节点master镜像
$ gpinitstandby -s smdw[gpadmin@gp-master ~]$ psql komablog -c 'SELECT procpid, state FROM pg_stat_replication;'
procpid | state
--------- -----------
32593 | streaming
(1 row)列出有关walsender进程的信息，该进程被用于镜像Greenplum数据库的Master。
- 检测失效的segment
在Greenplum数据库的Master主机上，Postgres的postmaster进程会派生一个故障探测进程ftsprobe。它有时也被称作FTS（容错服务器）进程。如果FTS失败，postmaster进程会重启它。
gpstate 工具
代码语言：javascript复制[gpadmin@gp-master ~]$ gpstate -m //显示镜像segment 实例信息
20191224:18:47:57:022244 gpstate:gp-master:gpadmin-[INFO]:-Starting gpstate with args: -m
20191224:18:47:57:022244 gpstate:gp-master:gpadmin-[INFO]:-local Greenplum Version: 'postgres (Greenplum Database) 5.21.1 build commit:ca0b8106b893028d18f241dcb858d85f12af90b6'
20191224:18:47:57:022244 gpstate:gp-master:gpadmin-[INFO]:-master Greenplum Version: 'PostgreSQL 8.3.23 (Greenplum Database 5.21.1 build commit:ca0b8106b893028d18f241dcb858d85f12af90b6) on x86_64-pc-linux-gnu, compiled by GCC gcc (GCC) 6.2.0, 64-bit compiled on Jul 24 2019 22:51:37'
20191224:18:47:57:022244 gpstate:gp-master:gpadmin-[INFO]:-Obtaining Segment details from master...
20191224:18:47:57:022244 gpstate:gp-master:gpadmin-[WARNING]:--------------------------------------------------------------
20191224:18:47:57:022244 gpstate:gp-master:gpadmin-[WARNING]:-physical mirroring not used
20191224:18:47:57:022244 gpstate:gp-master:gpadmin-[WARNING]:--------------------------------------------------------------[gpadmin@gp-master ~]$ gpstate -e //显示segment 镜像状态
20191224:18:48:25:022371 gpstate:gp-master:gpadmin-[INFO]:-Starting gpstate with args: -e
20191224:18:48:25:022371 gpstate:gp-master:gpadmin-[INFO]:-local Greenplum Version: 'postgres (Greenplum Database) 5.21.1 build commit:ca0b8106b893028d18f241dcb858d85f12af90b6'
20191224:18:48:25:022371 gpstate:gp-master:gpadmin-[INFO]:-master Greenplum Version: 'PostgreSQL 8.3.23 (Greenplum Database 5.21.1 build commit:ca0b8106b893028d18f241dcb858d85f12af90b6) on x86_64-pc-linux-gnu, compiled by GCC gcc (GCC) 6.2.0, 64-bit compiled on Jul 24 2019 22:51:37'
20191224:18:48:25:022371 gpstate:gp-master:gpadmin-[INFO]:-Obtaining Segment details from master...
20191224:18:48:25:022371 gpstate:gp-master:gpadmin-[INFO]:-Physical mirroring is not configured- 检查日志文件
$ gplogfilter -t
[gpadmin@gp-master ~]$ gplogfilter -t
requested timestamp range from beginning of data to end of data
---------- /data/master/gpseg-1/pg_log/gpdb-2019-12-24_153623.csv ----------
in: 57 lines, 57 log entries; timestamps from 2019-12-24 15:36:23.027330 to 2019-12-24 15:36:24.464534
match: 0 lines
out: 0 lines, 0 log entries
---------- /data/master/gpseg-1/pg_log/gpdb-2019-12-23_000000.csv ----------
in: 0 lines, 0 log entries; no timestamps found
match: 0 lines
out: 0 lines, 0 log entries
---------- /data/master/gpseg-1/pg_log/gpdb-2019-12-24_150758.csv ----------
in: 57 lines, 57 log entries; timestamps from 2019-12-24 15:07:58.102589 to 2019-12-24 15:07:59.531255
match: 0 lines
out: 0 lines, 0 log entries
---------- /data/master/gpseg-1/pg_log/gpdb-2019-12-24_164403.csv ----------
in: 57 lines, 57 log entries; timestamps from 2019-12-24 16:44:03.362180 to 2019-12-24 16:44:04.715757
match: 0 lines
out: 0 lines, 0 log entries//批量检查segment日志
gpssh -f seg_hosts -e 'source /usr/local/greenplum-db/greenplum_path.sh ; gplogfilter -t /data/primary/gpseg*/pg_log/gpdb*.csv' > seglog.out[gp-node1] source /usr/local/greenplum-db/greenplum_path.sh ; gplogfilter -t /data/primary/gpseg*/pg_log/gpdb*.csv
[gp-node1] requested timestamp range from beginning of data to end of data
[gp-node1] ---------- /data/primary/gpseg0/pg_log/gpdb-2019-12-19_164202.csv ----------
[gp-node1] in: 15 lines, 15 log entries; timestamps from 2019-12-19 16:42:02.777733 to 2019-12-19 16:42:03.762678
[gp-node1] match: 0 lines
[gp-node1] out: 0 lines, 0 log entries
[gp-node1] ---------- /data/primary/gpseg0/pg_log/gpdb-2019-12-19_164211.csv ----------
[gp-node1] in: 13 lines, 13 log entries; timestamps from 2019-12-19 16:42:11.012501 to 2019-12-19 16:42:11.791297
[gp-node1] match: 0 lines
[gp-node1] out: 0 lines, 0 log entries
[gp-node1] ---------- /data/primary/gpseg0/pg_log/gpdb-2019-12-20_000000.csv ----------
[gp-node1] in: 3 lines, 3 log entries; timestamps from 2019-12-20 15:03:05.230915 to 2019-12-20 15:03:05.296381
[gp-node1] match: 0 lines
[gp-node1] out: 0 lines, 0 log entries
[gp-node1] ---------- /data/primary/gpseg0/pg_log/gpdb-2019-12-20_151848.csv ----------
[gp-node1] in: 16 lines, 16 log entries; timestamps from 2019-12-20 15:18:48.992510 to 2019-12-20 15:32:28.987426
[gp-node1] match: 0 lines
[gp-node1] out: 0 lines, 0 log entries
[gp-node1] ---------- /data/primary/gpseg0/pg_log/gpdb-2019-12-20_153742.csv ----------
