1.初始化数据
postgres=# create database tdb01;
CREATE DATABASE
postgres=# \c tdb01
tdb01=# create table t1(id serial primary key,uname varchar(20));
CREATE TABLE
insert into t1 (uname) values ('mia');
insert into t1 (uname) values ('pg');
insert into t1 (uname) values ('redis');
tdb01=# select * from t1;
id | uname
----+-------
1 | mia
2 | pg
3 | redis
(3 rows)

tdb01=# select now();
now
//-------------------------------
2020-10-10 22:23:02.741721+08
(1 row)

tdb01=#
tdb01=#
tdb01=#
tdb01=# select now();
now
//-------------------------------
2020-10-10 22:23:14.938469+08
(1 row)

tdb01=#

2、创建基础备份

$ pg_basebackup -h 192.168.73.128 -D /pgbackup/ -U postgres
Password:
$

3、修改数据库

tdb01=# insert into t1 (uname) values ('mogodb');
INSERT 0 1
tdb01=# insert into t1 (uname) values ('oarcle');
INSERT 0 1
tdb01=# delete from t1;
DELETE 5
tdb01=# select * from t1;
id | uname
----+-------
(0 rows)

tdb01=# \q

4.停止数据库
[postgres@pg13 ~]$ pg_ctl stop -D /pgdata/
waiting for server to shut down.... done
server stopped
[postgres@pg13 /]$ exit
logout

5.重命名数据库目录，原目录(pgdata-->pgold),备份目录(pgbackup-->pgdata)
[root@pg13 ~]# cd /
[root@pg13 /]# mv pgdata pgold
[root@pg13 /]# mv pgbackup pgdata

6.复制运行时pg_wal到临时恢复目录
[postgres@pg13 pgold]$ pwd
/pgold
[postgres@pg13 pgold]$ cp -r pg_wal /home/postgres/
[postgres@pg13 pgold]$

7.验证WAL日志大小

[postgres@pg13 pgold]$ du -sh pg_wal/
657M pg_wal/
[postgres@pg13 pgold]$

[postgres@pg13 ~]$ du -sh pg_wal/
657M pg_wal/
[postgres@pg13 ~]$

8.创建recovery文件

[postgres@pg13 ~]$ cd /pgdata/
[postgres@pg13 pgdata]$ touch recovery.signal
[postgres@pg13 pgdata]$

9.配置恢复时间点
restore_command = 'cp /home/postgres/pg_wal/%f %p'
recovery_target_time = '2020-10-10 22:23:02.741721+08'
recovery_target_inclusive = off # just before the recovery target (off)

10.验证恢复

tdb01=# select * from t1;
id | uname
----+-------
1 | mia
2 | pg
3 | redis
(3 rows)

tdb01=#

默认恢复完成为#recovery_target_action = 'pause'，

tdb01=# show transaction_read_only ;
transaction_read_only
//-----------------------
on
(1 row)

tdb01=# select pg_is_in_recovery();
pg_is_in_recovery
//-------------------
t
(1 row)

tdb01=#
tdb01=# insert into t1 (uname) values ('golang');
ERROR: cannot execute INSERT in a read-only transaction
tdb01=#

11.切换为读写状态

tdb01=# select pg_promote();
pg_promote
//------------
t
(1 row)

tdb01=# insert into t1 (uname) values ('golang');
INSERT 0 1
tdb01=#