安装部署pg11.5

PostgreSQL是最强开源关系型数据库, 二进制文件只有20MB, 它的安装很简单, 今天我们学习编译安装

create db

编译安装建库，需包含文档及所有contrib

教程

• 源码下载地址
• wget https://ftp.postgresql.org/pub/source/v14beta2/postgresql-14beta2.tar.gz
• 源码编译安装Postgresql 11.4

apt源设置

参考
vim /etc/apt/sources.list, 添加如下

deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial main restricted universe multiverse
deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-updates main restricted universe multiverse
deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-backports main restricted universe multiverse
deb https://mirrors.tuna.tsinghua.edu.cn/ubuntu/ xenial-security main restricted universe multiverse

依赖

apt update
apt install gcc make libreadline6 libreadline6-dev
apt install zlib1g-dev #参考https://www.systutorials.com/how-to-install-the-zlib-library-in-ubuntu/

提前设置环境变量

• 设置在/etc/profile, 便于root/postgres/ubuntu各用户公用
• 如果切换到postgres/ubuntu用户时, source /etc/profile即可

groupadd postgres
useradd -g postgres postgres

环境变量

• 2.130的pg11在/usr/lib/postgres, pg13在PGNEWHOME里
• 注意PGHOME值得就是bin的上层目录, 其中有bin include lib share四个文件夹
• 同时设置了PGDATA, PGUSER, PGCOLOR, 这样直接输入psql命令就可以很方便的连接PG, 免去输入缺省参数的烦恼

export PGNEWHOME=/platformData/pgnewhome
mkdir -p $PGNEWHOME
#chown -R postgres:postgres $PGNEWHOME

export PGNEWDATA=/platformData/pgnewdata
mkdir -p $PGNEWDATA
#chown -R postgres:postgres $PGNEWDATA

export PGNEWSOURCE=/platformData/pgnewsource
mkdir -p $PGNEWSOURCE
#chown -R postgres:postgres $PGNEWSOURCE

export PATH="$PGNEWHOME/bin:$PATH"
export LD_LIBRARY_PATH="$PGNEWHOME/lib:$LD_LIBRARY_PATH"

export PGDATA=$PGNEWDATA
export PGDATABASE=postgres
export PGUSER=postgres
export PG_COLOR=always
echo $PGUSER $PGNEWHOME $PGNEWDATA $PGNEWSOURCE

export LANG=en_US.utf8
export DATE=`date +"%Y-%m-%d %H:%M:%S"`
alias ll='ls -lh'

export PGDATA=/platformData/postgresql/11/main
export PATH="/usr/lib/postgresql/11/bin":$PATH

• 注意切换用户要用su - postgres(这样才会把执行环境也切换掉), 而不要用su postgres

正式安装

# 开始编译
cd $PGNEWSOURCE/postgresql-13.1 && ./configure --prefix=$PGNEWHOME && make world && make install

这个prefix指的是二进制$PGNEWHOME的路径 (其下会有bin/include/lib/share4个文件夹)

make world (和make一样均为4min)

• extensions安装

cd $PGNEWSOURCE/postgresql-13.1/contrib && make && make install

• 新建用户

groupadd postgres && useradd -g postgres postgres
groupadd y && useradd -g y y

• 更改属组

cd /platformData && chown -R postgres:postgres pgnew*

• 目录

postgres@db130:/platformData/pgnewhome/bin$ ls
clusterdb   dropdb    initdb	  pg_archivecleanup  pg_checksums    pg_ctl	 pg_isready	 pg_resetwal  pg_test_fsync   pg_verifybackup  postmaster  vacuumdb
createdb    dropuser  oid2name	  pg_basebackup      pg_config	     pg_dump	 pg_receivewal	 pg_restore   pg_test_timing  pg_waldump       psql	   vacuumlo
createuser  ecpg      pg_amcheck  pgbench	     pg_controldata  pg_dumpall  pg_recvlogical  pg_rewind    pg_upgrade      postgres	       reindexdb

initdb

# 注意职能在postgres用户下执行
postgres@ubuntu:/platformData/pgnewhome/bin$ ./initdb -D $PGNEWDATA --data-checksums

启动

./pg_ctl -D /platformData/pgnewdata start

• 准备便捷启动脚本

root@db130:/platformData/pgnewhome/bin# cat pgstop.sh
# /bin/bash
su - postgres -c "pg_ctl stop -D $PGNEWDATA"
root@db130:/platformData/pgnewhome/bin# cat pgstart.sh
# /bin/bash
su - postgres -c "pg_ctl start -D $PGNEWDATA"
root@db130:/platformData/pgnewhome/bin# cat pgrestart.sh
# /bin/bash
bash pgstop.sh
bash pgstart.sh

• 开机自动启动

在/etc/rc.local中添加
su postgres -c "/usr/lib/postgresql/bin/pg_ctl -D /data/postgres start

• 命令行传递参数

su postgres -c "/usr/lib/postgresql/11/bin/pg_ctl start -D /data/data_gas/citus_fake_nodes/worker5433/db_data -o \"-h '*' -p 5433\""

设置密码

ALTER USER postgres WITH PASSWORD 'postgres';

设定层级子账号, 隔离权限

PostgreSQL 用户组权限管理

• 先通过postgres user建admin user;
• 接下来就可以admin user 建 subuser1, subuser2, 并grant subuser1与2 to admin;
• admin 建t_admin; subuser1建t_subuser1; subuser2建t_subuser2;
• 然后各subuser虽能看到所有表名, 但都只能select * from 自己的表;

• admin也可以把t_subuser1表 的权限 给其他subuser2用户
  

目录

pgdata:/u01/app/pg11/pgdata
pghome:/u01/app/pg11/pghome
pg waldir:/pg_wal

设置环境变量

http://www.postgres.cn/docs/11/libpq-envars.html

network

端口5433,监听所有IP

cd $PGNEWDATA && vim postgresql.conf
port = 5433
listen_addresses = '*'

authicen

本地postgres用户无需密码登录，其他用户需密码

cd $PGNEWDATA && vim pg_hba.conf
local   all             all                                     trust
host    all             all             0.0.0.0/0               md5

允许任意ip的任意用户连接任意数据库,需密码

同上

管理

parameter

log

• 打开日志，格式csvlog
• 日志目录 /u01/app/pglog
• 日志最大size 50MB
• 每天切一个日志
• 同名日志覆盖

cd $PGNEWDATA && vim postgresql.conf

logging_collector = on # 打开日志, 必要条件
log_destination = 'csvlog' # 格式csvlog
log_directory = 'pg_log' # 日志目录 /u01/app/pglog
log_rotation_size = 50MB # 日志最大size 50MB
log_rotation_age = 1d #每天切一个日志
log_truncate_on_rotation = on #同名日志覆盖

pg_ctl -D $PGNEWDATA start

查日志

pg14的日志格式必须参照官网

外部表定义参照digoal

alisql详细定义

CREATE EXTENSION file_fdw;  
CREATE SERVER pglog FOREIGN DATA WRAPPER file_fdw;
CREATE FOREIGN TABLE pglog (
  log_time timestamp(3) with time zone,
  user_name text,
  database_name text,
  process_id integer,
  connection_from text,
  session_id text,
  session_line_num bigint,
  command_tag text,
  session_start_time timestamp with time zone,
  virtual_transaction_id text,
  transaction_id bigint,
  error_severity text,
  sql_state_code text,
  message text,
  detail text,
  hint text,
  internal_query text,
  internal_query_pos integer,
  context text,
  query text,
  query_pos integer,
  location text,
  application_name text,
  backend_type text
) SERVER pglog 
OPTIONS ( program 'find /platformData/pgnewdata/log -type f -name "*.csv" -exec cat {} \;', format 'csv' ); 

配置归档(删除7天前的归档)

• 归档目录:/pg_arch

mdkir /platformData/pg_arch # pg不会自动建目录, 需要使用者手动建目录, 因为下面的命令都是目标文件存在才会拷贝归档
# 尽量不要放在$PGNEWDATA下, 那就没有归档的意义了, 应分离放在别的目录

archive_mode = on
archive_command = 'cp %p /platformData/pg_arch/%f'
# 如果打开test ! -f会导致pg_switch_wal()实验失败
# 如果打开删除前x天的文件, 也会有问题
# 'test ! -f /platformData/pg_arch/%f && cp %p /platformData/pg_arch/%f && find /pg_arch/ -type f -mtime +7 -exec rm -f {} \;'

在pgsql中手动触发归档

产生的归档如下:

创建一个用户user1,最大连接数为10,work_mem为1MB

ALTER ROLE (ALTER USER是其别名)

# 最大连接数10 和 登陆
create user user1;
alter role user1 login;
alter role user1 CONNECTION LIMIT 10;
psql -d postgres -U user1 -p 5433
select current_user;

# 改密码
alter role user1 with password '123';
psql -d postgres -U user1 -p 123 -p5433

# 设置内存
ALTER ROLE user1 SET maintenance_work_mem = 10000;
alter role user1 set work_mem = 10000;

sql

创建pg_stat_statements插件并启用

https://www.postgresql.org/docs/11/pgstatstatements.html

# 配置文件
shared_preload_libraries = 'pg_stat_statements'
# 重启生效
pg_ctl start -D $PGNEWDATA
create extension pg_stat_statements  

记录最大sql数量为10000

pg_stat_statements.max = 10000
pg_stat_statements.track = all

sql语句记录最大字节为4096

log记录所有ddl语句

log_statement = 'ddl'

重置一次pg_stat_statements

SELECT pg_stat_statements_reset();

template设置

postgresql 表空间创建、删除

创建一个新的表空间pg_tbs位置/pgdata/pg_tbs

mkdir -p /pg_tbs #一般不要和$PGNEWDATA放在一起
postgres=# create tablespace tbs owner postgres location '/pg_tbs'; # 表空间只能用绝对路径, 注意表空间不要已pg开头

create table t (id integer) tablespace tbs;

create database yy with template xx: 可用于复制数据库xx到yy

pg 常见各种操作, 其中包括template相关的

默认模板数据库的默认表空间为pg_tbs

ALTER DATABASE template1 SET TABLESPACE tbs;

回收所有普通用户对public的操作权限

http://postgres.cn/docs/11/sql-revoke.html

所有用户?? 目前只能revoke单个用户的…

revoke all PRIVILEGES on schema public from user1;

所有以默认模板创建的库包含一个public.dual表,任意用户可操作

• 设置模板库

postgres=# \c template1
You are now connected to database "template1" as user "postgres".
template1=# \d
Did not find any relations.
template1=# create table tb_default1(id int8);
template1=# insert into tb_default1 values (1);
template1=# insert into tb_default1 values (2);
template1=# insert into tb_default1 values (3);
template1=# \d
            List of relations
 Schema |    Name     | Type  |  Owner
--------+-------------+-------+----------
 public | tb_default1 | table | postgres

• 应用模板库

postgres=# create database c;
postgres=# \c c
CREATE DATABASE
c=# select * from tb_default1 ;
 id
----
  1
  2
  3

以template0创建一个数据库db1

c=# create database db1 template template0;
CREATE DATABASE
c=# \c db1
You are now connected to database "db1" as user "postgres".
db1=# \d
Did not find any relations.

pg partition

db:postgres user:postgres schema:public

创建range分区表t1_range, 以gmt_time为分区创建三个分区

• t1_range_p2018:2018及以前的数据
• t1_range_p201901:2019年1月份的数据
• t1_range_p20190201:2019年2月1号的数据
• 注意如果要建二级分区参考pg多级分区, create partition句尾要加PARTITION BY RANGE (a);

create table t1_range (name text, gmt_time timestamp) partition by range (gmt_time);

create table t1_range_p2018 partition of t1_range for values from 
('-infinity') to ('2018-01-01 00:00:00');

-- 建一级分区时指定partition by range
create table t1_range_p201901 partition of t1_range for values from 
('2019-01-01 00:00:00') to ('2019-02-01 00:00:00') partition by range (gmt_time);

-- 这是二级分区
create table t1_range_p20190101 partition of t1_range_p201901 for values from ('2019-01-01 00:00:00') to ('2019-01-02 00:00:00');

create table t1_range_p20190201 partition of t1_range for values from 
('2019-02-01 00:00:00') to ('2019-02-02 00:00:00');

创建组合分区

• 创建t1_range的一个range分区t1_range_p2020 (2020全年数据)

create table if not exists t1_range (name text, gmt_time timestamp) partition by range (gmt_time);

create table t1_range_2020 partition of t1_range for values from
 ('2020-01-01 00:00:00') to ('2021-01-01 00:00:00') partition by list(name);

• 创建t1_range_p2020的一个分list分区,(name为分区键，包含’AAA’,‘BBBB’)
  • pg分区表
  • CREATE TABLE
  • Table Partitioning

create table t1_range_2020_a partition of t1_range_2020 for values in ('AAA', 'BBB');

备份,主备

backup

pg_basebackup流程图原理

pg_basebackup源码原理

pg中checkPoint原理

full_page_writes陈华军

full_page_write EDB

简单讲就是pg在启动时先recovery, 会读wal, apply wal, apply时需要在每个页上apply, (每个page上记录了已经落盘的pd_lsn)

而page可能被损坏(如pg以8KB写入, linux以4KB为原子写入, 所以一个pg的page可能在崩溃的时候 只写了4KB(即一半, 没写完))

解决方式: checkPoint之后, 对每个page的第一次修改, 都要把整个page写入WAL, 这样在checkPoint之后, 就可以从WAL恢复出整个page => 拿到整个page的pd_lsn => apply每一行WAL记录

题目要求

• 执行以下脚本

db:postgres  user:postgres  schema:public
create table t1(id int);
insert into t1 (id) values (1),(2),(3);

• 正常操作

pg_basebackup备份全库
insert into t1 (id) values (4),(5),(6);

• 误操作

insert into t1 (id) values (7),(8),(9);
drop table t1;

• 发现7.3为误操作，恢复数据库到7.3 insert前的时间点

操作答案

• 前置准备

• 执行pg_switch_wal之前

• 执行pg_switch_wal()
  

• 开始操作

• 新建bak文件夹, 用于存放pg_basebackup的文件

• 开始pg_basebackup(必须su -postgres用户下才可执行, su postgres都不行…)

• 写入正常数据+开始落盘wal

• 此时123456都把wal落盘了, 可靠的时间为 2021-01-23 21:54:18.826786+08, 然后insert 789三条数据

• 然后模拟数据库宕机
  

• 把PGDATA备份到PGDATAbak, 然后删掉PGDATA
  

• 然后启动数据库发现起不来

• 把base_backup的/bak的base.tar文件拷贝到这里PGDATA目录

• 把base_backup的/bak的pg_wal.tar文件拷贝到这里PGDATA目录
  

• 然后启动pg, 发现只有123

• 把归档的wal拷到PGDATA里

  • /pg_archive是放wal的归档路径, 因为pg_switch_wal()了, 所以456三行会在/pg_archive中, 所以需要cp pg_archive/* pgnewdata/pg_wal

  • 而pg_base_backup产生的/bak目录下的base.tar+pg_wal.tar中有123三行数据

  • 所以启动后会在base.tar+pg_wal.tar的基础上, 应用/pg_archive, 会得到123456六行数据

• 拷贝备份的表空间到PGDATA/pg_tblspc(存疑, 好像这一步不需要)

mkdir -p /platformData/pgnewdata/pg_tblspc/16685
cd /platformData/pgnewdata/pg_tblspc/16685
cp /bak/16685.tar .
tar -xf 16685.tar

• 12和13是编辑postgres.conf(pg11是recovery.conf)
  

• 启动pg

  • 会产生standby.signal
    

  • pg_log如下

root@db47:/platformData/pgnewdata# cat pg_log/postgresql-2021-03-13_211442.csv
2021-03-13 21:14:42.937 CST,,,85054,,604cbac2.14c3e,1,,2021-03-13 21:14:42 CST,,0,LOG,00000,"ending log output to stderr",,"Future log output will go to log destination ""csvlog"".",,,,,,,"","postmaster"
2021-03-13 21:14:42.937 CST,,,85054,,604cbac2.14c3e,2,,2021-03-13 21:14:42 CST,,0,LOG,00000,"starting PostgreSQL 13.1 on x86_64-pc-linux-gnu, compiled by gcc (Ubuntu 5.4.0-6ubuntu1~16.04.11) 5.4.0 20160609, 64-bit",,,,,,,,,"","postmaster"
2021-03-13 21:14:42.937 CST,,,85054,,604cbac2.14c3e,3,,2021-03-13 21:14:42 CST,,0,LOG,00000,"listening on IPv4 address ""0.0.0.0"", port 5432",,,,,,,,,"","postmaster"
2021-03-13 21:14:42.937 CST,,,85054,,604cbac2.14c3e,4,,2021-03-13 21:14:42 CST,,0,LOG,00000,"listening on IPv6 address ""::"", port 5432",,,,,,,,,"","postmaster"
2021-03-13 21:14:43.023 CST,,,85054,,604cbac2.14c3e,5,,2021-03-13 21:14:42 CST,,0,LOG,00000,"listening on Unix socket ""/tmp/.s.PGSQL.5432""",,,,,,,,,"","postmaster"
2021-03-13 21:14:43.111 CST,,,85056,,604cbac3.14c40,1,,2021-03-13 21:14:43 CST,,0,LOG,00000,"database system was interrupted; last known up at 2021-03-13 18:05:46 CST",,,,,,,,,"","startup"
2021-03-13 21:14:43.371 CST,,,85056,,604cbac3.14c40,2,,2021-03-13 21:14:43 CST,,0,LOG,00000,"entering standby mode",,,,,,,,,"","startup"
2021-03-13 21:14:43.400 CST,,,85056,,604cbac3.14c40,3,,2021-03-13 21:14:43 CST,,0,LOG,00000,"restored log file ""000000010000000000000018"" from archive",,,,,,,,,"","startup"
2021-03-13 21:14:43.714 CST,,,85056,,604cbac3.14c40,4,,2021-03-13 21:14:43 CST,1/0,0,LOG,00000,"redo starts at 0/18000028",,,,,,,,,"","startup"
2021-03-13 21:14:43.745 CST,,,85056,,604cbac3.14c40,5,,2021-03-13 21:14:43 CST,1/0,0,LOG,00000,"consistent recovery state reached at 0/18000100",,,,,,,,,"","startup"
2021-03-13 21:14:43.745 CST,,,85054,,604cbac2.14c3e,6,,2021-03-13 21:14:42 CST,,0,LOG,00000,"database system is ready to accept read only connections",,,,,,,,,"","postmaster"
2021-03-13 21:14:43.773 CST,,,85056,,604cbac3.14c40,6,,2021-03-13 21:14:43 CST,1/0,0,LOG,00000,"restored log file ""000000010000000000000019"" from archive",,,,,,,,,"","startup"
2021-03-13 21:14:44.046 CST,,,85056,,604cbac3.14c40,7,,2021-03-13 21:14:43 CST,1/0,0,LOG,00000,"restored log file ""00000001000000000000001A"" from archive",,,,,,,,,"","startup"
2021-03-13 21:14:44.291 CST,,,85056,,604cbac3.14c40,8,,2021-03-13 21:14:43 CST,1/0,0,LOG,00000,"restored log file ""00000001000000000000001B"" from archive",,,,,,,,,"","startup"
2021-03-13 21:14:44.532 CST,,,85056,,604cbac3.14c40,9,,2021-03-13 21:14:43 CST,1/0,0,LOG,00000,"restored log file ""00000001000000000000001C"" from archive",,,,,,,,,"","startup"
2021-03-13 21:14:44.766 CST,,,85056,,604cbac3.14c40,10,,2021-03-13 21:14:43 CST,1/0,0,LOG,00000,"restored log file ""00000001000000000000001D"" from archive",,,,,,,,,"","startup"
2021-03-13 21:14:45.000 CST,,,85056,,604cbac3.14c40,11,,2021-03-13 21:14:43 CST,1/0,0,LOG,00000,"restored log file ""00000001000000000000001E"" from archive",,,,,,,,,"","startup"
2021-03-13 21:14:45.214 CST,,,85056,,604cbac3.14c40,12,,2021-03-13 21:14:43 CST,1/0,0,LOG,00000,"recovery stopping before commit of transaction 1545, time 2021-03-13 18:18:35.253716+08",,,,,,,,,"","startup"
2021-03-13 21:14:45.214 CST,,,85056,,604cbac3.14c40,13,,2021-03-13 21:14:43 CST,1/0,0,LOG,00000,"pausing at the end of recovery",,"Execute pg_wal_replay_resume() to promote.",,,,,,,"","startup"

• 此时数据已经恢复了

• 然后执行select pg_wal_replay_resume(), 以去除pg的只读模式

> pg1213会自动把standby.signal清除掉

> pg11会发现recovery.conf会变成recovery.done

pg_log会打印如下

2021-03-13 21:24:09.801 CST,,,85056,,604cbac3.14c40,14,,2021-03-13 21:14:43 CST,1/0,0,LOG,00000,"redo done at 0/1E000230",,,,,,,,,"","startup"
2021-03-13 21:24:09.801 CST,,,85056,,604cbac3.14c40,15,,2021-03-13 21:14:43 CST,1/0,0,LOG,00000,"last completed transaction was at log time 2021-03-13 18:07:46.284416+08",,,,,,,,,"","startup"
2021-03-13 21:24:10.043 CST,,,85056,,604cbac3.14c40,16,,2021-03-13 21:14:43 CST,1/0,0,LOG,00000,"selected new timeline ID: 2",,,,,,,,,"","startup"
2021-03-13 21:24:10.313 CST,,,85056,,604cbac3.14c40,17,,2021-03-13 21:14:43 CST,1/0,0,LOG,00000,"archive recovery complete",,,,,,,,,"","startup"
2021-03-13 21:24:10.641 CST,,,85054,,604cbac2.14c3e,7,,2021-03-13 21:14:42 CST,,0,LOG,00000,"database system is ready to accept connections",,,,,,,,,"","postmaster"

一般在生产环境做增量备份的方式:

每天业务低峰期(7天的话增量恢复时间太慢了)1个全量pg_basebackup拷贝到一个备份目录(主要消耗磁盘IO), 然后在全量基础上应用pg_archive做增量.

master-slave

考点: 用pg_basebackup备份, 然后用pg_promote把从变主

pg12流复制-能跑通

创建2个流复制备库，端口5434同步只读备库, 端口5435异步只读备库

• 主库设置

# master
root@db47:/platformData# su - postgres
postgres@db47:/platformData$ initdb -D /platformData/db-master
/platformData/pgnewhome/bin/pg_ctl start -D /platformData/db-master

############# db-master/postgresql.conf #############
# 连接
listen_addresses = '*'
port = 5432

# 归档: 确保将WAL文件归档到从属群集可以访问的位置, ％f将替换为目标WAL文件的文件名，而％p将替换为目标WAL文件的路径
archive_mode = on
archive_command = 'cp %p /platformData/pg_arch/%f'

# 流复制
wal_level = replica 默认就有
max_wal_senders = 10 默认就有
wal_keep_size = 0 默认就有
hot_standby = on 默认就有

# 其他: 必须启用pg_rewind工具才能使其正常工作
wal_log_hints = on

############# db-master/pg_hba.conf #############
# 确保主群集允许从从群集远程复制连接
# Allow replication connections from 127.0.0.1, by a user with the replication privilege.
# TYPE  DATABASE        USER            ADDRESS                 METHOD
host    replication     all             127.0.0.1/32            trust

# 使用上述配置文件启动master数据库集群，创建具有复制权限的超级用户，以及一个名为clusterdb的数据库。
$ pg_ctl -D db-master start
$ createuser cary -s --replication
$ createdb clusterdb

# 将一些测试数据插入主群集。为简单起见，我们将向test_table插入100个整数。
$ psql -d clusterdb -U cary -c "CREATE TABLE test_table(x integer)"
CREATE TABLE
$ psql -d clusterdb -U cary -c "INSERT INTO test_table(x) SELECT y FROM generate_series(1, 100) a(y)"
INSERT 0 100
$ psql -d clusterdb -U cary -c "SELECT count(*) from test_table"
 count 
-------
   100
(1 row)

• 从库设置
  • 异步从库如下
  • 同步从库再
    • 在主库的postgresql.conf中增加
      • synchronous_commit=off/local/remote_write/remote_apply/on(默认就是on)
      • synchronous_standby_names=‘node2’
    • 在从库postgresql.auto.conf中的primary_conninfo增加
      • application_name=node2

pg_basebackup -h 127.0.0.1 -U cary -p 5432 -D db-slave1 -P -Xs -R
# 其中-D是从库的数据路径, -h -U -p 都是主库的连接信息, -P是显示进度, -Xs表示以stream模式并行接收wal部分, -R表示在备库创建standby.signal文件

postgres@db47:/platformData$ ls db-slave1/
backup_label	 pg_ident.conf	pg_stat      pg_xact
backup_manifest  pg_logical	pg_stat_tmp  postgresql.auto.conf
base		 pg_multixact	pg_subtrans  postgresql.conf
global		 pg_notify	pg_tblspc    standby.signal
pg_commit_ts	 pg_replslot	pg_twophase
pg_dynshmem	 pg_serial	PG_VERSION
pg_hba.conf	 pg_snapshots	pg_wal

# 让我们先检查一下db-slave/postgresql.auto.conf，我们将看到pg_basebackup已经为我们创建了primary_conninfo, 它告诉从群集应从何处, 以及如何从主群集中流式传输。确保postgresql.auto.conf中存在此行。
postgres@db47:/platformData$ cat db-slave1/postgresql.auto.conf
# Do not edit this file manually!
# It will be overwritten by the ALTER SYSTEM command.
primary_conninfo = 'user=cary passfile=''/var/lib/postgresql/.pgpass'' channel_binding=disable host=127.0.0.1 port=5432 sslmode=disable sslcompression=0 ssl_min_protocol_version=TLSv1.2 gssencmode=disable krbsrvname=postgres target_session_attrs=any'

# 让我们检查db-slave/postgresql.conf并更新一些参数: 相比主库port不同, 且多了restore_command和archive_cleanup_command的部分
# 由于db-slave/postgresql.conf是通过pg_basebackup从主群集直接复制的，因此我们需要将其更改为port与主端口不同的端口（在本例中为5433），因为两者都在同一台计算机上运行。我们将需要填写restore_command和archive_cleanup_command让从属群集知道如何获取已归档的WAL文件以进行流传输。这两个参数曾经在recovery.conf中定义，PG12将其移至postgresql.conf中。
############# db-slave/postgresql.conf #############
# 连接
listen_addresses = '*'
port = 5433

# 归档: 确保将WAL文件归档到从属群集可以访问的位置, ％f将替换为目标WAL文件的文件名，而％p将替换为目标WAL文件的路径
archive_mode = on
archive_command = 'cp %p /platformData/pg_arch/%f'

# 流复制
wal_level = replica 默认就有
max_wal_senders = 10 默认就有
wal_keep_size = 0 默认就有
hot_standby = on 默认就有

# 其他: 必须启用pg_rewind工具才能使其正常工作
wal_log_hints = on 通过pg_basebackup的话默认会和主库相同

# 从库恢复的命令
restore_command = 'cp /platformData/pg_arch/%f %p'
archive_cleanup_command = 'pg_archivecleanup /platformData/pg_arch/ %r'

# 请注意，在db-slave目录中，standby.signal将自动创建一个新文件，pg_basebackup指示该从集群将以standby模式运行。

# 现在，让我们启动从集群：
$ pg_ctl -D db-slave1 start

• 验证流复制

# 一旦主集群和从集群都已设置并运行，我们应该从ps -ef命令中看到一些后端进程已启动来实现复制，即walsender和walreceiver。
postgres@db47:/platformData$ ps -ef | grep wal
postgres  45300  45296  0 16:32 ?        00:00:00 postgres: walwriter
postgres  47897  47886  0 16:50 ?        00:00:00 postgres: walreceiver streaming 0/3000148
postgres  47898  45296  0 16:50 ?        00:00:00 postgres: walsender cary 127.0.0.1(22158) streaming 0/3000148

# 还可以通过向主集群发出查询来详细检查复制状态
postgres@db47:/platformData$ psql -d clusterdb -U cary -c "select * from pg_stat_replication;" -x -p 5432
-[ RECORD 1 ]----+------------------------------
pid              | 47898
usesysid         | 16386
usename          | cary
application_name | walreceiver
client_addr      | 127.0.0.1
client_hostname  |
client_port      | 22158
backend_start    | 2021-03-14 16:50:55.378784+08
backend_xmin     |
state            | streaming
sent_lsn         | 0/3000148
write_lsn        | 0/3000148
flush_lsn        | 0/3000148
replay_lsn       | 0/3000148
write_lag        |
flush_lag        |
replay_lag       |
sync_priority    | 0
sync_state       | async
reply_time       | 2021-03-14 16:52:25.548362+08

# 最后，我们可以将其他数据插入主群集，并验证从属群集是否也更新了数据。
postgres@db47:/platformData$ psql -d clusterdb -U cary -c "SELECT count(*) from test_table" -p 5433
 count
-------
   100
(1 row)

postgres@db47:/platformData$ psql -d clusterdb -U cary -c "SELECT count(*) from test_table" -p 5432
 count
-------
   100
(1 row)

postgres@db47:/platformData$ psql -d clusterdb -U cary -c "INSERT INTO test_table(x) SELECT y FROM generate_series(1, 100) a(y)" -p 5432
INSERT 0 100

postgres@db47:/platformData$ psql -d clusterdb -U cary -c "SELECT count(*) from test_table" -p 5433
 count
-------
   200
(1 row)

• 设置复制槽

前面的步骤说明了如何正确设置主群集和从群集之间的流复制。但是，在某些情况下，由于某些原因，从属服务器可能会断开连接，从而导致时间延长，并且当某些未复制的WAL文件被回收或从wal_keep_segments参数控制的主群集中删除时，可能无法与主服务器进行复制。

复制槽确保主服务器可以为所有从服务器保留足够的WAL段，防止主服务器删除可能导致从服务器上发生恢复冲突的行。

让我们在主集群上创建一个复制槽slave：

postgres@db47:/platformData$ psql -d clusterdb -U cary -c "select * from pg_create_physical_replication_slot('slave')" -p 5432
 slot_name | lsn
-----------+-----
 slave     |
(1 row)

postgres@db47:/platformData$ psql -d clusterdb -U cary -c "select * from pg_replication_slots" -x -p 5432
-[ RECORD 1 ]-------+---------
slot_name           | slave
plugin              |
slot_type           | physical
datoid              |
database            |
temporary           | f
active              | f
active_pid          |
xmin                |
catalog_xmin        |
restart_lsn         |
confirmed_flush_lsn |
wal_status          |
safe_wal_size       |

# 我们刚刚在master上创建了复制槽slave，该复制槽当前未处于活动状态（active = f）
# 让我们修改从属服务器postgresql.conf并使其连接到主服务器的复制槽
############# db-slave/postgresql.conf #############
primary_slot_name = 'slave'

# 重启从库生效
pg_ctl restart -D db-slave1/

# 如果一切正常，则检查主服务器上的复制槽的插槽状态应为活动状态。
postgres@db47:/platformData$ psql -d clusterdb -U cary -c "select * from pg_replication_slots" -x -p 5432
-[ RECORD 1 ]-------+---------
slot_name           | slave
plugin              |
slot_type           | physical
datoid              |
database            |
temporary           | f
active              | f
active_pid          |
xmin                |
catalog_xmin        |
restart_lsn         |
confirmed_flush_lsn |
wal_status          |
safe_wal_size       |

当5434宕机, 5435可升为同步备库

pg多个同步复制服务器
基于优先级的多同步后备的synchronous_standby_names示例1：

synchronous_standby_names = ‘db5434, db5435’

在这个例子中，db5434是同步备库，db5435为潜在同步备库，当db5434不可用时，db5435升级为同步备库

主备切换

pg12主备切换-实验ok
5434升为主库, 5435为同步备库, 5433延迟6小时应用日志

• 关老主库模拟主库宕机
• 提老从库
• 老主库设置standby.signal和primary_conninfo, 然后重启老主库

延迟应用日志

pgsql物理复制（pgsql 备库的搭建以及角色互换，提升）

pg延迟备库-自己实验是ok的

echo "recovery_min_apply_delay = 6h" >> /opt/data5556/postgresql.conf

强化：应用管理

对象管理

目的: 把热表放在ssd, ssd建一个表空间

使用超级用户创建应用用户appuser，赋权createdb、login，创建属主为appuser的表空间并命名为exam，指向/exam（若没有此目录请自行创建并管理权限），切换到appuser用户创建app数据库（要求app数据库要在exam表空间内），在app数据库中创建app表（id int）。

pg的登录、创建用户、数据库并赋权

postgres=# create user appuser;
CREATE ROLE

# 用户赋权
postgres=# alter role appuser createdb;
ALTER ROLE
postgres=# alter role appuser login;
ALTER ROLE
postgres=# \du
                                   List of roles
 Role name |                         Attributes                         | Memb
er of
-----------+------------------------------------------------------------+-
 appuser   | Create DB                                                  | {}
 postgres  | Superuser, Create role, Create DB, Replication, Bypass RLS | {}
 repuser   | Replication                                               +| {}
           | 5 connections

# 建表空间
root@db47:~# mkdir /exam
root@db47:~# chown postgres:postgres /exam/
postgres=# create tablespace exam location '/exam';
CREATE TABLESPACE

# 赋'表空间'的权给user
postgres=# grant all  PRIVILEGES ON tablespace exam to appuser;
GRANT


# 登陆
postgres@db47:/opt$ psql -p5555 -Uappuser
psql (13.1)
Type "help" for help.


# 建库建表
postgres=> create database app tablespace exam;
CREATE DATABASE
postgres=> \c app;
You are now connected to database "app" as user "appuser".
app=> create table app (id int);
CREATE TABLE

逻辑导入

使用psql工具，导入exam.sql到app库中（注：sql文件中包含student表和exam表）。

SET statement_timeout = 0;
SET lock_timeout = 0;
SET idle_in_transaction_session_timeout = 0;
SET client_encoding = 'UTF8';
SET standard_conforming_strings = on;
SET check_function_bodies = false;
SET client_min_messages = warning;
SET row_security = off;

CREATE EXTENSION IF NOT EXISTS plpgsql WITH SCHEMA pg_catalog;
COMMENT ON EXTENSION plpgsql IS 'PL/pgSQL procedural language';
SET search_path = public, pg_catalog;
SET default_tablespace = '';
SET default_with_oids = false;

CREATE TABLE exam (
    name character varying(10),
    subject character varying(10),
    score integer
);
ALTER TABLE exam OWNER TO appuser;

CREATE TABLE student (
    id integer,
    name character varying(10),
    age integer
);
ALTER TABLE student OWNER TO appuser;

INSERT INTO exam VALUES ('张三', '英语', 78);
INSERT INTO exam VALUES ('张三', '语文', 68);
INSERT INTO exam VALUES ('张三', '数学', 99);
INSERT INTO exam VALUES ('李四', '语文', 89);
INSERT INTO exam VALUES ('李四', '数学', NULL);
INSERT INTO exam VALUES ('李四', '英语', 57);
INSERT INTO exam VALUES ('王五', '语文', 55);
INSERT INTO exam VALUES ('王五', '数学', 77);
INSERT INTO exam VALUES ('赵六', '语文', 79);
INSERT INTO exam VALUES ('赵六', '数学', 48);
INSERT INTO exam VALUES ('赵六', '英语', 27);

INSERT INTO student VALUES (1, '张三', 14);
INSERT INTO student VALUES (2, '李四', 14);
INSERT INTO student VALUES (3, '王五', 15);
INSERT INTO student VALUES (4, '赵六', 16);
INSERT INTO student VALUES (5, '吴七', 15);

root@db47:/platformData# psql -f exam.sql -p5555
SET
SET
SET
SET
SET
SET
SET
SET
CREATE EXTENSION
COMMENT
SET
SET
SET
CREATE TABLE
ALTER TABLE
CREATE TABLE
ALTER TABLE
INSERT 0 1
INSERT 0 1
INSERT 0 1
INSERT 0 1
INSERT 0 1
INSERT 0 1
INSERT 0 1
INSERT 0 1
INSERT 0 1
INSERT 0 1
INSERT 0 1
INSERT 0 1
INSERT 0 1
INSERT 0 1
INSERT 0 1
INSERT 0 1

逻辑导出

使用pgdump工具导出一份sql文件，命名为answer.sql。（使用-f选项即可. -f选项的文本用psql恢复, 其他格式的用pg_restore恢复）。

root@db47:/platformData# pg_dump -Fp -p5555 -fanswer.sql

root@db47:/platformData# tail answer.sql
5	2021-03-14 18:08:28.069683+08
6	2021-03-14 19:45:24.094873+08
7	2021-03-14 19:47:01.302179+08
\.
--
-- PostgreSQL database dump complete
--

物理备份

配置postgresql，开启归档所需相关参数（wal_level、archive_mode、archive_command），归档目录为/exam，重启数据库使参数生效，然后切换一次wal日志（pg_switch_wal），在/exam中查看是否归档成功。使用pg_basebackup对数据库做一次基础备份（目录为/backup，请注意目录权限，使用-Fp格式，并将exam表空间备份到/backup/exam，选项提示-D -Fp -Xs -v -h -U -T）。

mkdir -p /exam
chown -R postgres:postgres /exam

wal_level = replica
archive_mode = on
archive_command = 'cp %p /exam/%f'

postgres@db47:~$ cd /platformData/
postgres@db47:/platformData$ pg_ctl restart -D data5555/

# 建目录
root@db47:/exam# mkdir -p /backup
root@db47:/exam# chown -R postgres:postgres  /backup

# 开始备份
postgres@db47:/platformData$ pg_basebackup -D /backup -Fp -Xs -v -h127.0.0.1 -p5555 -Upostgres --tablespace-mapping=/exam=/backup/exam
pg_basebackup: initiating base backup, waiting for checkpoint to complete
pg_basebackup: checkpoint completed
pg_basebackup: write-ahead log start point: 0/F000028 on timeline 3
pg_basebackup: starting background WAL receiver
pg_basebackup: created temporary replication slot "pg_basebackup_109279"
pg_basebackup: write-ahead log end point: 0/F000100
pg_basebackup: waiting for background process to finish streaming ...
pg_basebackup: syncing data to disk ...
pg_basebackup: renaming backup_manifest.tmp to backup_manifest
pg_basebackup: base backup completed

# 检查结果
root@db47:/exam# cd /backup/
root@db47:/backup# ls
backup_label     pg_dynshmem    pg_serial     PG_VERSION
backup_manifest  pg_hba.conf    pg_snapshots  pg_wal
base             pg_ident.conf  pg_stat       pg_xact
exam             pg_logical     pg_stat_tmp   postgresql.auto.conf
global           pg_multixact   pg_subtrans   postgresql.conf
log              pg_notify      pg_tblspc
pg_commit_ts     pg_replslot    pg_twophase
root@db47:/backup# ls exam
PG_13_202007201

PITR恢复

使用数据库超级用户删除app库中的exam表，查看此时的时间戳（current_timestamp）。切换一次wal日志（pg_switch_wal），关闭数据库，并将此数据目录mv为data.bak文件，将基础备份放到数据目录下。配置此时数据目录（基础备份）中的recovery.conf文件（restore_command、recovery_target_time、recovery_target_timeline），将删除的表恢复。启动数据库，查看是否有删除的exam表。

# 因为上一步骤已经做过pg_basepackup, 备份到/backup了

# 此时先drop表
postgres=# drop table exam;
DROP TABLE

# 切换使wal落盘
postgres=# select pg_switch_wal();
 pg_switch_wal
---------------
 0/10005470
(1 row)

# 查看当前时间, 推算出故障前的时间点
postgres=# select now();
              now
-------------------------------
 2021-03-15 09:14:19.013383+08
(1 row)
假设故障点是5min前, 则为 2021-03-15 09:09:19.013383+08

# 检查是否pg_wal落盘了: 000000030000000000000010是已归档的文件, 000000030000000000000011是正在写的wal
postgres@db47:/platformData/data5555$ ll -rt pg_wal/
total 81M
-rw------- 1 postgres postgres   41 Mar 14 18:05 00000002.history
-rw------- 1 postgres postgres   83 Mar 14 18:07 00000003.history
-rw------- 1 postgres postgres  16M Mar 15 00:04 000000030000000000000012
-rw------- 1 postgres postgres  16M Mar 15 00:09 000000030000000000000013
-rw------- 1 postgres postgres  16M Mar 15 00:09 000000030000000000000014
-rw------- 1 postgres postgres  337 Mar 15 00:09 00000003000000000000000F.00000028.backup
-rw------- 1 postgres postgres  16M Mar 15 09:12 000000030000000000000010
drwx------ 2 postgres postgres 4.0K Mar 15 09:12 archive_status
-rw------- 1 postgres postgres  16M Mar 15 09:12 000000030000000000000011

# 检查wal是否归档了: 000000030000000000000010是已归档的文件, 确实已经归档了
postgres@db47:/platformData/data5555$ grep archive_command postgresql.conf
archive_command = 'cp %p /exam/%f'		# command to use to archive a logfile segment

postgres@db47:/platformData/data5555$ ll -rt /exam/
total 65M
drwxr-x--- 3 postgres postgres 4.0K Mar 14 20:12 PG_13_202007201
-rw------- 1 postgres postgres  16M Mar 15 00:04 00000003000000000000000D
-rw------- 1 postgres postgres  16M Mar 15 00:09 00000003000000000000000E
-rw------- 1 postgres postgres  16M Mar 15 00:09 00000003000000000000000F
-rw------- 1 postgres postgres  337 Mar 15 00:09 00000003000000000000000F.00000028.backup
-rw------- 1 postgres postgres  16M Mar 15 09:12 000000030000000000000010

# 关闭数据库
postgres@db47:/platformData$ pg_ctl stop -D data5555/
waiting for server to shut down.... done
server stopped

# 备份数据路径
postgres@db47:/platformData$ mv data5555/ data5555.bak
postgres@db47:/platformData$ ls
data5555.bak  exam.sql	pg_arch  pgnewhome  pgnewdata  pgnewsource  pgnewtablespace  restart.sh	start.sh

# 把pg_basebackup备份的数据拷贝过来, 作为基数据
postgres@db47:/platformData$ mkdir data5555
postgres@db47:chmod 0750 data5555
postgres@db47:/platformData$ ls /backup
backup_label	 exam	 pg_commit_ts  pg_ident.conf  pg_notify    pg_snapshots  pg_subtrans  PG_VERSION  postgresql.auto.conf
backup_manifest  global  pg_dynshmem   pg_logical     pg_replslot  pg_stat	 pg_tblspc    pg_wal	  postgresql.conf
base		 log	 pg_hba.conf   pg_multixact   pg_serial    pg_stat_tmp	 pg_twophase  pg_xact
postgres@db47:/platformData$ cp -r  /backup/* data5555


# 改postgresql.conf的restore_command、recovery_target_time、recovery_target_timeline配置
archive_command = 'cp %p /exam/%f'
restore_command = 'cp /exam/%f %p'
recovery_target_time = '2021-03-15 09:09:19.013383+08'
recovery_target_timeline = 'latest'     # 'current', 'latest', or timeline ID

# 然后重启数据库看是否能恢复
postgres@db47:/platformData$ pg_ctl start -D data5555
waiting for server to start....2021-03-15 09:29:55.294 CST [184823] LOG:  starting PostgreSQL 13.1 on x86_64-pc-linux-gnu, compiled by gcc (Ubuntu 5.4.0-6ubuntu1~16.04.11) 5.4.0 20160609, 64-bit
2021-03-15 09:29:55.294 CST [184823] LOG:  listening on IPv6 address "::1", port 5555
2021-03-15 09:29:55.294 CST [184823] LOG:  listening on IPv4 address "127.0.0.1", port 5555
2021-03-15 09:29:55.373 CST [184823] LOG:  listening on Unix socket "/tmp/.s.PGSQL.5555"
2021-03-15 09:29:55.440 CST [184824] LOG:  database system was interrupted; last known up at 2021-03-15 00:09:53 CST
2021-03-15 09:29:55.816 CST [184824] LOG:  redo starts at 0/F000028
2021-03-15 09:29:55.848 CST [184824] LOG:  consistent recovery state reached at 0/F000100
2021-03-15 09:29:55.848 CST [184824] LOG:  redo done at 0/F000100
.2021-03-15 09:29:56.268 CST [184823] LOG:  database system is ready to accept connections
 done
server started

# 检查发现exam表确实被恢复了
root@db47:~# psql -p5555
psql (13.1)
Type "help" for help.

postgres=# \d
          List of relations
 Schema |  Name   | Type  |  Owner
--------+---------+-------+----------
 public | exam    | table | appuser
 public | student | table | appuser
 public | t       | table | postgres
(3 rows)

postgres=# select * from exam;
 name | subject | score
------+---------+-------
 张三 | 英语    |    78
 张三 | 语文    |    68
 张三 | 数学    |    99
 李四 | 语文    |    89
 李四 | 数学    |
 李四 | 英语    |    57
 王五 | 语文    |    55
 王五 | 数学    |    77
 赵六 | 语文    |    79
 赵六 | 数学    |    48
 赵六 | 英语    |    27
(11 rows)

流复制主库（host1）配置：

创建复制角色rep，设置登录（login）和复制（replication）权限，并设置密码为123。在pg_hba.conf中设置rep用户可以从对应网段进行流复制请求。配置postgresql.conf（listen_addresses、max_wal_senders、wal_level、wal_keep_segments）,重启数据库。

postgres=# create user rep;
CREATE ROLE
postgres=# alter user rep login;
ALTER ROLE
postgres=# alter user rep replication;
ALTER ROLE
postgres=# alter user rep with password '123';
ALTER ROLE

# pg_hba.conf设置如下
host    replication     rep             127.0.0.1/32            md5

# postgresql.conf设置如下
listen_addresses = '*'
max_wal_senders = 10 默认就有
wal_level = replica 默认就有
wal_keep_size = 100 # in megabytes; 0 disables

# 重启主库生效
postgres@db47:/platformData$ pg_ctl restart -D data5555

流复制备库（host2）配置：

创建数据目录，在备库使用pg_basebackup拉取主库的数据形成基础备份放到备库的数据目录下，配置备库数据目录下的recovery.conf文件（recovery_target_timeline、standby_mode、primary_conninfo），启动备库。查看流复制相关进程是否存在，并在主库的app表插入一条数据，在备库验证是否有此数据。

• 经验:
  最好不要带表空间, 否则会有各种问题, 比如如下备库总会找不到文件而进入recovery模式

waiting for server to start....2021-03-15 10:06:37.486 CST [190236] LOG:  starting PostgreSQL 13.1 on x86_64-pc-linux-gnu, compiled by gcc (Ubuntu 5.4.0-6ubuntu1~16.04.11) 5.4.0 20160609, 64-bit
2021-03-15 10:06:37.487 CST [190236] LOG:  listening on IPv4 address "0.0.0.0", port 5556
2021-03-15 10:06:37.487 CST [190236] LOG:  listening on IPv6 address "::", port 5556
2021-03-15 10:06:37.562 CST [190236] LOG:  listening on Unix socket "/tmp/.s.PGSQL.5556"
2021-03-15 10:06:37.640 CST [190237] LOG:  database system was shut down in recovery at 2021-03-15 10:06:28 CST
cp: cannot stat '/exam/00000004.history': No such file or directory
2021-03-15 10:06:37.644 CST [190237] LOG:  entering standby mode
cp: cannot stat '/exam/00000003.history': No such file or directory
2021-03-15 10:06:37.676 CST [190237] LOG:  restored log file "000000030000000000000015" from archive
2021-03-15 10:06:37.908 CST [190237] LOG:  redo starts at 0/15000060
2021-03-15 10:06:37.938 CST [190237] LOG:  restored log file "000000030000000000000016" from archive
2021-03-15 10:06:38.174 CST [190237] LOG:  consistent recovery state reached at 0/16000318
2021-03-15 10:06:38.174 CST [190237] LOG:  recovery stopping before commit of transaction 529, time 2021-03-15 09:55:04.807326+08
2021-03-15 10:06:38.174 CST [190237] LOG:  pausing at the end of recovery
2021-03-15 10:06:38.174 CST [190237] HINT:  Execute pg_wal_replay_resume() to promote.
2021-03-15 10:06:38.174 CST [190236] LOG:  database system is ready to accept read only connections

• 正文

# 做pg_basebackup做备库的base数据
postgres@db47:/platformData$ pg_basebackup -Fp -h127.0.0.1 -p5555 -Urep -D data5556 -P -v -Xs

# 数据会自动备份好
root@db47:/platformData# ls data5556
backup_label      exam          pg_dynshmem    pg_multixact  pg_snapshots  pg_tblspc    pg_xact
backup_label.old  global        pg_hba.conf    pg_notify     pg_stat       pg_twophase  postgresql.auto.conf
backup_manifest   log           pg_ident.conf  pg_replslot   pg_stat_tmp   PG_VERSION   postgresql.conf
base              pg_commit_ts  pg_logical     pg_serial     pg_subtrans   pg_wal       standby.signal

# 配置会自动写好
root@db47:/platformData# grep recovery_target_timeline data5556/postgresql.conf
recovery_target_timeline = 'latest'	# 'current', 'latest', or timeline ID
root@db47:/platformData# grep primary_conninfo data5556/postgresql.auto.conf
primary_conninfo = 'user=rep passfile=''/var/lib/postgresql/.pgpass'' channel_binding=disable host=127.0.0.1 port=5555 sslmode=disable sslcompression=0 ssl_min_protocol_version=TLSv1.2 gssencmode=disable krbsrvname=postgres target_session_attrs=any'

# 需要改端口号
root@db47:/platformData# grep port data5556/postgresql.conf
port = 5456				# (change requires restart)
wal_log_hints = on

# 然后启动备库
postgres@db47:/platformData$ pg_ctl start -D data5556
waiting for server to start....2021-03-15 09:49:00.864 CST [187647] LOG:  starting PostgreSQL 13.1 on x86_64-pc-linux-gnu, compiled by gcc (Ubuntu 5.4.0-6ubuntu1~16.04.11) 5.4.0 20160609, 64-bit
2021-03-15 09:49:00.864 CST [187647] LOG:  listening on IPv4 address "0.0.0.0", port 5456
2021-03-15 09:49:00.864 CST [187647] LOG:  listening on IPv6 address "::", port 5456
2021-03-15 09:49:00.946 CST [187647] LOG:  listening on Unix socket "/tmp/.s.PGSQL.5456"
2021-03-15 09:49:00.985 CST [187647] LOG:  could not open directory "pg_tblspc/16392/PG_13_202007201": No such file or directory
2021-03-15 09:49:01.027 CST [187648] LOG:  database system was interrupted; last known up at 2021-03-15 09:45:45 CST
cp: cannot stat '/exam/00000004.history': No such file or directory
2021-03-15 09:49:01.291 CST [187648] LOG:  entering standby mode
cp: cannot stat '/exam/00000003.history': No such file or directory
2021-03-15 09:49:01.323 CST [187648] LOG:  restored log file "000000030000000000000014" from archive
2021-03-15 09:49:01.543 CST [187648] LOG:  could not open directory "pg_tblspc/16392/PG_13_202007201": No such file or directory
2021-03-15 09:49:01.594 CST [187648] LOG:  could not open directory "pg_tblspc/16392/PG_13_202007201": No such file or directory
2021-03-15 09:49:01.595 CST [187648] LOG:  redo starts at 0/14000028
2021-03-15 09:49:01.627 CST [187648] LOG:  consistent recovery state reached at 0/14000100
2021-03-15 09:49:01.627 CST [187647] LOG:  database system is ready to accept read only connections
cp: cannot stat '/exam/000000030000000000000015': No such file or directory
 done
server started
postgres@db47:/platformData$ 2021-03-15 09:49:01.674 CST [187670] LOG:  started streaming WAL from primary at 0/15000000 on timeline 3

# 主库如下1
postgres=# \d
          List of relations
 Schema |  Name   | Type  |  Owner
--------+---------+-------+----------
 public | exam    | table | appuser
 public | student | table | appuser
 public | t       | table | postgres
 
 postgres=# show port;
 port
------
 5555
(1 row)
 
# 从库如下1
postgres=# \d
      List of relations
Schema |  Name   | Type  |  Owner
--------+---------+-------+----------
public | exam    | table | appuser
public | student | table | appuser
public | t       | table | postgres

postgres=# show port;
 port
------
 5556
(1 row)

# 主库如下2
postgres=# select count(*) from t;
 count
-------
     8
(1 row)

postgres=# insert into t values(101, now());
INSERT 0 1

# 从库如下2
postgres=# select count(*) from t;
 count
-------
     8
(1 row)

# 主库如下3
postgres=# select count(*) from t;
 count
-------
     8
(1 row)

postgres=# select * from t;
 id  |             info
-----+-------------------------------
   1 | 2021-03-14 17:57:43.71824+08
   2 | 2021-03-14 17:57:43.918607+08
   3 | 2021-03-14 18:03:23.617959+08
 100 | 2021-03-14 18:06:14.945316+08
   5 | 2021-03-14 18:07:59.478954+08
   5 | 2021-03-14 18:08:28.069683+08
   6 | 2021-03-14 19:45:24.094873+08
   7 | 2021-03-14 19:47:01.302179+08
(8 rows)

# 从库如下3
postgres=# select count(*) from t;
 count
-------
     8
(1 row)

主备切换：

模拟主库故障(关库)，提升备库的状态，将备库变为可读写的单库。

# 模拟主库故障(关库)
postgres@db47:/platformData$ pg_ctl stop -D data5555
waiting for server to shut down.... done
server stopped

# 提升备库的状态，将备库变为可读写的单库
postgres=# show port;
 port
------
 5556
(1 row)

postgres=# select pg_promote();
 pg_promote
------------
 t
(1 row)

# 此时'老备库'日志可看出已经提升成功
2021-03-16 13:15:30.169 CST [190237] LOG:  received promote request
2021-03-16 13:15:30.169 CST [190237] LOG:  redo done at 0/16000318
cp: cannot stat '/exam/00000004.history': No such file or directory
2021-03-16 13:15:30.288 CST [190237] LOG:  selected new timeline ID: 4
2021-03-16 13:15:30.537 CST [190237] LOG:  archive recovery complete
cp: cannot stat '/exam/00000003.history': No such file or directory
2021-03-16 13:15:30.689 CST [190236] LOG:  database system is ready to accept connections

# 然后发现'老备库'作为单库, 确实可以做写操作了
postgres=# \d
          List of relations
 Schema |  Name   | Type  |  Owner
--------+---------+-------+----------
 public | exam    | table | appuser
 public | student | table | appuser
 public | t       | table | postgres
(3 rows)

postgres=# select * from t;
 id  |             info
-----+-------------------------------
   1 | 2021-03-14 17:57:43.71824+08
   2 | 2021-03-14 17:57:43.918607+08
   3 | 2021-03-14 18:03:23.617959+08
 100 | 2021-03-14 18:06:14.945316+08
   5 | 2021-03-14 18:07:59.478954+08
   5 | 2021-03-14 18:08:28.069683+08
   6 | 2021-03-14 19:45:24.094873+08
   7 | 2021-03-14 19:47:01.302179+08
(8 rows)

postgres=# insert into t values(200, now());
INSERT 0 1

同步流复制：

在原主库（host1）数据目录的配置文件中设置（synchronous_standby_names），重启数据库。并设置备库（host2）的recovery.conf，重启数据库。查看相关流复制进程，并插入测试数据。模拟备库宕机，向主库的app数据库中的app表中插入一条数据看是否夯住。

# 搭建过程同上, 注意在主库设置sychronous_standby_names和在从库设置application_name, 假设现在已经搭建好了同步流复制

# 模拟备库宕机(手动停掉备库)
postgres@db47:/platformData$ pg_ctl stop -D data5433
waiting for server to shut down.... done
server stopped

2021-03-16 14:37:50.822 CST [25244] LOG:  received fast shutdown request
2021-03-16 14:37:50.872 CST [25244] LOG:  aborting any active transactions
2021-03-16 14:37:50.873 CST [25285] FATAL:  terminating connection due to administrator command
2021-03-16 14:37:50.873 CST [25249] FATAL:  terminating walreceiver process due to administrator command
2021-03-16 14:37:50.874 CST [25246] LOG:  shutting down
2021-03-16 14:37:51.203 CST [25244] LOG:  database system is shut down

# 主库仍然可查
postgres=# show port;
 port
------
 5432
(1 row)

postgres=# select * from t;
 id
----
  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
(10 rows)

# 写入会被hang住
# 但是在psql中手动ctrl + C, 仍然会在主库写入
postgres=# insert into t select generate_series(1,10);
^CCancel request sent
WARNING:  canceling wait for synchronous replication due to user request
DETAIL:  The transaction has already committed locally, but might not have been replicated to the standby.
INSERT 0 10

postgres=# delete from t;
^CCancel request sent
WARNING:  canceling wait for synchronous replication due to user request
DETAIL:  The transaction has already committed locally, but might not have been replicated to the standby.
DELETE 20

逻辑复制，订阅发布模型配置（使用超级用户）：

将上面的流复制恢复为两台单机，设置配置文件（wal_level），在发布主机的app库中创建test表（id int,name text），并对test表创建发布者pub；在订阅主机的app库中创建test表（id int,name text），然后创建订阅者sub（连接信息host、port、dbname）。在发布主机上向test表中插入一条数据，在订阅主机上做refresh操作并查看数据是否复制成功。

关键就是wal_level = logical

# 将上面的流复制恢复为两台单机
postgres@db47:/platformData$ initdb -D data5432
postgres@db47:/platformData$ initdb -D data5433

# 设置配置文件
listen_addresses = '*'
port = 5432和5433

archive_mode = on
archive_command = 'cp %p /platformData/pg_arch/%f'

wal_level = logical
max_wal_senders = 10 默认就有
wal_keep_size = 0 默认就有
hot_standby = on 默认就有

wal_log_hints = on

# 启动
pg_ctl start -D data5432
pg_ctl start -D data5433

# 在发布主机的app库中创建test表（id int,name text），并对test表创建发布者pub
postgres@db47:/platformData/data5432$ psql
psql (13.1)
Type "help" for help.

postgres=# show port;
 port
------
 5432
(1 row)

postgres=# create database app;
CREATE DATABASE
postgres=# \c app;
You are now connected to database "app" as user "postgres".
app=# create table test(id int, name text);
CREATE TABLE

app=# create publication pub for table test;
CREATE PUBLICATION

# 在订阅主机的app库中创建test表（id int,name text），然后创建订阅者sub（连接信息host、port、dbname）
postgres@db47:/platformData/data5433$ psql -p 5433
psql (13.1)
Type "help" for help.

postgres=# show port;
 port
------
 5433
(1 row)

postgres=# create database app;
CREATE DATABASE
postgres=# \c app;
You are now connected to database "app" as user "postgres".
app=# create table test(id int, name text);
CREATE TABLE

app=# CREATE SUBSCRIPTION sub CONNECTION 'host=127.0.0.1 port=5432 dbname=app user=postgres password=postgres' PUBLICATION pub;
NOTICE:  created replication slot "sub" on publisher
CREATE SUBSCRIPTION

# 复制前主库
app=# show port;
 port
------
 5432
(1 row)

app=# select * from test;
 id | name
----+------
(0 rows)

# 复制前从库
app=# show port;
 port
------
 5433
(1 row)

app=# select * from test;
 id | name
----+------
(0 rows)

# 复制后主库
app=# show port;
 port
------
 5432
(1 row)

app=# insert into test select generate_series(1,5);
INSERT 0 5

app=# select * from test;
 id | name
----+------
  1 |
  2 |
  3 |
  4 |
  5 |
(5 rows)

# 复制后从库
app=# show port;
 port
------
 5433
(1 row)

app=# select * from test;
 id | name
----+------
  1 |
  2 |
  3 |
  4 |
  5 |
(5 rows)

强化练习：SQL实验

1. 目前在app数据库中有两张表，student表与exam表，并有以下数据，如果没有，请使用exam.sql文件重新导入，SQL题目暂不考查权限与对象相关知识，可用超级用户在任意数据库中导入，只需有以下数据即可。

app=# \i /platformData/exam.sql

app=# \d
          List of relations
 Schema |  Name   | Type  |  Owner
--------+---------+-------+----------
 public | exam    | table | postgres
 public | student | table | postgres

app=# select * from student ;
 id | name | age
----+------+-----
  1 | 张三 |  14
  2 | 李四 |  14
  3 | 王五 |  15
  4 | 赵六 |  16
  5 | 吴七 |  15
(5 rows)

app=# select * from exam;
 name | subject | score
------+---------+-------
 张三 | 英语    |    78
 张三 | 语文    |    68
 张三 | 数学    |    99
 李四 | 语文    |    89
 李四 | 数学    |
 李四 | 英语    |    57
 王五 | 语文    |    55
 王五 | 数学    |    77
 赵六 | 语文    |    79
 赵六 | 数学    |    48
 赵六 | 英语    |    27
(11 rows)

2. 查询exam表中每科考试的最高分及平均分（结果显示字段：学科exam.subject，最高分maxscore，平均分avgscore）。

SELECT subject, max(score) AS maxscore, avg(score) AS avgscore
FROM exam
GROUP BY subject;

+-------+--------+-------------------+
|subject|maxscore|avgscore           |
+-------+--------+-------------------+
|语文     |89      |72.75              |
|英语     |78      |54                 |
|数学     |99      |74.6666666666666667|
+-------+--------+-------------------+

3. 查询英语分数比英语平均分高的考生（结果显示字段：考生id，考生name，考生age，英语分数score）。

参考

SELECT s.id, s.name, s.age, e.score
FROM student s
         INNER JOIN exam e ON s.name = e.name
WHERE e.subject = '英语'
  AND e.score > (SELECT avg(score) FROM exam WHERE subject = '英语');
                                                             
+--+----+---+-----+
|id|name|age|score|
+--+----+---+-----+
|1 |张三  |14 |78   |
|2 |李四  |14 |57   |
+--+----+---+-----+

-- 因结果都大于54, 故正确

4. 请使用case表达式，条件当subject为英语时，abc_subject结果显示A英语；当subject为语文时，abc_subject结果显示B语文；当subject为数学时，abc_subject结果显示C数学（结果显示字段：考生name，学科abc_subject）。

SELECT name,
       CASE subject
           WHEN '英语' THEN 'A英语'
           WHEN '语文' THEN 'B语文'
           WHEN '数学' THEN 'C数学'
           ELSE '' END
           AS abc_subject
FROM exam;

+----+-----------+
|name|abc_subject|
+----+-----------+
|张三  |A英语        |
|张三  |B语文        |
|张三  |C数学        |
|李四  |B语文        |
|李四  |C数学        |
|李四  |A英语        |
|王五  |B语文        |
|王五  |C数学        |
|赵六  |B语文        |
|赵六  |C数学        |
|赵六  |A英语        |
+----+-----------+

5. 基于student和exam表创建一张视图student_view，查询此视图时可得到以age列倒序，每个考生每门考试的成绩（结果显示字段：考生name，考生age，学科subject，成绩score，）。

CREATE OR REPLACE VIEW student_view AS
SELECT s.name, s.age, e.subject, e.score
FROM student s
         INNER JOIN exam e ON s.name = e.name
ORDER BY s.age DESC;

+----+---+-------+-----+
|name|age|subject|score|
+----+---+-------+-----+
|赵六  |16 |英语     |27   |
|赵六  |16 |数学     |48   |
|赵六  |16 |语文     |79   |
|王五  |15 |数学     |77   |
|王五  |15 |语文     |55   |
|张三  |14 |数学     |99   |
|李四  |14 |语文     |89   |
|张三  |14 |语文     |68   |
|张三  |14 |英语     |78   |
|李四  |14 |英语     |57   |
|李四  |14 |数学     |NULL |
+----+---+-------+-----+

6. 使用窗口函数rank()，查询出以subject分组且以score排序后，每科目的考生成绩（结果显示字段：考生name，科目subject，成绩score，及排序数值ranking）。

pg的rank()函数用法

pg官网的rank函数

SELECT s.name,
       e.subject,
       e.score,
       rank()
       OVER
           (PARTITION BY e.subject ORDER BY e.score DESC)
FROM student s
         INNER JOIN exam e ON s.name = e.name;
                                  
+----+-------+-----+----+
|name|subject|score|rank|
+----+-------+-----+----+
|李四  |数学     |NULL |1   |
|张三  |数学     |99   |2   |
|王五  |数学     |77   |3   |
|赵六  |数学     |48   |4   |
|张三  |英语     |78   |1   |
|李四  |英语     |57   |2   |
|赵六  |英语     |27   |3   |
|赵六  |语文     |100  |1   |
|李四  |语文     |89   |2   |
|赵六  |语文     |79   |3   |
|张三  |语文     |68   |4   |
|王五  |语文     |55   |5   |
+----+-------+-----+----+

7. 使用sum()函数计算数学科目的累计值（current_score列），要求current_score列根据score列逐个累加（结果显示字段：学科subject，成绩score，累计值current_score）。

SELECT e.subject, e.score, sum(e.score) OVER (PARTITION BY e.subject ORDER BY score ASC)
FROM exam e
WHERE e.subject = '数学';

+-------+-----+---+
|subject|score|sum|
+-------+-----+---+
|数学     |48   |48 |
|数学     |77   |125|
|数学     |99   |224|
|数学     |NULL |224|
+-------+-----+---+

8. 使用rollup()函数，同时得出每科目成绩的小计和成绩的总合计值（结果显示字段：成绩subject，合计值sum_score）。

rollup的用法

SELECT e.subject, sum(e.score) AS sum_score
FROM exam e
GROUP BY ROLLUP (e.subject)
ORDER BY subject;

+-------+---------+
|subject|sum_score|
+-------+---------+
|数学     |224      |
|英语     |162      |
|语文     |391      |
|NULL   |777      |
+-------+---------+

9. 基于exam创建物化视图exam_view，可以根据此视图查询出每科成绩的最高分（结果显示字段：学科subject，最高分max_score）。向exam表中添加一行数据：“赵六 语文 100”，然后刷新物化视图exam_view。

CREATE MATERIALIZED VIEW IF NOT EXISTS exam_view AS
SELECT e.subject, max(e.score) AS max_score
FROM exam e
GROUP BY e.subject;

SELECT * FROM exam_view;
+-------+---------+
|subject|max_score|
+-------+---------+
|语文     |89       |
|英语     |78       |
|数学     |99       |
+-------+---------+


-- 向exam表中添加一行数据：“赵六 语文 100”，查询没变化
INSERT INTO exam
VALUES ('赵六', '语文', 100);

SELECT * FROM exam_view;
+-------+---------+
|subject|max_score|
+-------+---------+
|语文     |89       |
|英语     |78       |
|数学     |99       |
+-------+---------+

-- 然后刷新物化视图exam_view, 查询变化了
REFRESH MATERIALIZED VIEW exam_view;
SELECT * FROM exam_view;
+-------+---------+
|subject|max_score|
+-------+---------+
|语文     |100      |
|英语     |78       |
|数学     |99       |
+-------+---------+

10. 创建范围分区表，以id为分区键，主表postgres（id int，name varchar），分区表a区间在（0-100），分区表b区间在（100-500），分区表c区间在（500-1000）。插入三条数据，“1 a”、“200 b”、“999 c”，查询主表及各分区表。

CREATE TABLE postgres
(
    id   int,
    name varchar
) PARTITION BY RANGE (id);

CREATE TABLE a PARTITION OF postgres FOR VALUES FROM (0) TO (100);
CREATE TABLE b PARTITION OF postgres FOR VALUES FROM (100) TO (500);
CREATE TABLE c PARTITION OF postgres FOR VALUES FROM (500) TO (1000);

app=# \d+ postgres
                                 Partitioned table "public.postgres"
 Column |       Type        | Collation | Nullable | Default | Storage  | Stats target | Description
--------+-------------------+-----------+----------+---------+----------+--------------+-------------
 id     | integer           |           |          |         | plain    |              |
 name   | character varying |           |          |         | extended |              |
Partition key: RANGE (id)
Partitions: a FOR VALUES FROM (0) TO (100),
            b FOR VALUES FROM (100) TO (500),
            c FOR VALUES FROM (500) TO (1000)
            
INSERT INTO postgres VALUES (1, 'a');
INSERT INTO postgres VALUES (200, 'b');
INSERT INTO postgres VALUES (999, 'c');

app=# select * from postgres;
 id  | name
-----+------
   1 | a
 200 | b
 999 | c
(3 rows)

app=# select * from a;
 id | name
----+------
  1 | a
(1 row)

app=# select * from b;
 id  | name
-----+------
 200 | b
(1 row)

app=# select * from c;
 id  | name
-----+------
 999 | c
(1 row)