一,
基本原理和步骤
备份:
使用pg_basebackup命令来进行备份,这个命令可以将postgresql的数据文件备份为两个压缩文件:base.tar和 pg_wal.tar。本别是数据文件和归档文件,恢复的时候,需要设置按照归档文件来恢复。那么,此种方式的备份可以备份自定义表空间。
恢复:
需要先把备份的压缩文件替换当前的数据文件,然后修改postgresql.conf,因为这个配置文件在data文件夹中,所以只能是在把base.tar解压到数据库当前数据位置,也就是我们默认初始化指定的数据保存位置data文件夹中,才能修改配置,在配置好归档设置以后,可以启动pgsql服务,进行启动恢复。
在恢复过程中,会拷贝归档文件,进行数据恢复。
恢复成功,也就是数据库服务启动成功。这个时候我们访问数据库,它是作为归档状态存在的,所以只能读,不能写操作。
为了恢复数据库写操作,我们需要在命令行下执行切换数据库状态的指令。切换成功之后,才可以进行读写操作。
二,
实操示例
环境介绍:
数据库主节点,IP:192.168.123.60,数据库端口:5432,数据库安装路径为/usr/local/pgsql ,管理用户为pg1
1,
创建一个自定义表空间
创建表空间存放路径
[root@EULER1 ~]# mkdir /opt/custome-tablespace
[root@EULER1 ~]# chown -Rf pg1. /opt/custome-tablespace/
登陆命令行,创建表空间
[root@EULER1 ~]# su - pg1 -c "psql -Upostgres -p 5432 -h 192.168.123.60"
Password for user postgres:
psql (12.5)
Type "help" for help.
postgres=# create tablespace mytbs location '/opt/custome-tablespace';
CREATE TABLESPACE
postgres=# \db+
List of tablespaces
Name | Owner | Location | Access privileges | Options | Size | Description
------------+----------+-------------------------+-------------------+---------+---------+-------------
mytbs | postgres | /opt/custome-tablespace | | | 0 bytes |
pg_default | pg1 | | | | 23 MB |
pg_global | pg1 | | | | 623 kB |
(3 rows)
此时的$PGDATA目录下的pg_tblspc目录下有一个软链接:
[root@EULER1 ~]# ls -al /usr/local/pgsql/data/pg_tblspc/
total 8
drwx------. 2 pg1 pg1 4096 Mar 19 20:06 .
drwx------. 20 pg1 pg1 4096 Mar 19 18:39 ..
lrwxrwxrwx 1 pg1 pg1 23 Mar 19 20:06 32771 -> /opt/custome-tablespace
创建一个新库和新表在此表空间内:
postgres=# create database test;
CREATE DATABASE
postgres=# alter database test set tablespace mytbs;
ALTER DATABASE
postgres=# \c test
You are now connected to database "test" as user "postgres".
test=# create table tb_mytps(i int,name varchar(32)) tablespace mytbs;
CREATE TABLE
插入实验数据:
insert into tb_mytps(i,name) values(2,'name2');
insert into tb_mytps(i,name) values(3,'name3');
insert into tb_mytps(i,name) values(4,'name4');
insert into tb_mytps(i,name) values(5,'name5');
insert into tb_mytps(i,name) values(6,'name6');
insert into tb_mytps(i,name) values(7,'name7');
insert into tb_mytps(i,name) values(8,'name8');
insert into tb_mytps(i,name) values(9,'name9');
insert into tb_mytps(i,name) values(10,'name10');
查看是否正确插入数据:
postgres=# \c test
You are now connected to database "test" as user "postgres".
test=# select * from tb_mytps ;
i | name
----+--------
1 | name1
2 | name2
3 | name3
4 | name4
5 | name5
6 | name6
7 | name7
8 | name8
9 | name9
10 | name10
(10 rows)
2,
开始备份
建立备份文件存放路径
[root@EULER1 ~]# mkdir /opt/backup
[root@EULER1 ~]# chown -Rf pg1. /opt/backup
可以看到有两个tablespace被备份了,-z -Z 5是压缩等级,范围是0-9, -Ft是tar包格式备份
[root@EULER1 ~]# su - pg1 -c "pg_basebackup -D /opt/backup -Ft -z -Z 5 -Pv -Upostgres -h 192.168.123.60 -p5432"
pg_basebackup: initiating base backup, waiting for checkpoint to complete
pg_basebackup: checkpoint completed
pg_basebackup: write-ahead log start point: 0/8000028 on timeline 2
pg_basebackup: starting background WAL receiver
pg_basebackup: created temporary replication slot "pg_basebackup_119924"
32567/32567 kB (100%), 2/2 tablespaces
pg_basebackup: write-ahead log end point: 0/8000100
pg_basebackup: waiting for background process to finish streaming ...
pg_basebackup: syncing data to disk ...
pg_basebackup: base backup completed
查看备份的文件:
[root@EULER1 backup]# ls -al /opt/backup/
total 48968
drwx------ 2 pg1 pg1 4096 Mar 19 20:27 .
drwxr-xr-x. 5 root root 4096 Mar 19 20:24 ..
-rw------- 1 pg1 pg1 8162304 Mar 19 20:27 32771.tar
-rw------- 1 pg1 pg1 25188352 Mar 19 20:27 base.tar
-rw------- 1 pg1 pg1 16780288 Mar 19 20:27 pg_wal.tar
备份完成后,删除test数据库,看看一会能否恢复。
3,
恢复
停止数据库:
[root@EULER1 ~]# bash ~/stop-pgsql.sh
waiting for server to shut down.... done
server stopped
删除原库的数据文件:
[root@EULER1 ~]# rm -rf /usr/local/pgsql/data/*
[root@EULER1 ~]# rm -rf /opt/custome-tablespace/*
解压备份文件到对应路径:
要注意是解压到哪里
[root@EULER1 ~]# tar xf /opt/backup/32771.tar -C /opt/custome-tablespace/
[root@EULER1 ~]# tar xf /opt/backup/base.tar -C /usr/local/pgsql/data/
创建wal文件存放路径:
赋予数据库管理用户权限,最后一个命令不能忘
[root@EULER1 ~]# mkdir /usr/local/pgsql/wal-back
[root@EULER1 ~]# tar xf /opt/backup/pg_wal.tar -C /usr/local/pgsql/wal-back/
[root@EULER1 data]# chown -Rf pg1. /usr/local/pgsql/
修改postgresql.conf文件:
任选一种恢复方式
a,立刻恢复:
restore_command = 'cp /usr/local/pgsql/wal-back/%f %p'
recovery_target = 'immediate'
b,可以按时间线恢复到最新:
恢复到最新:
restore_command = 'cp /usr/local/pgsql/wal-back/%f %p'
recovery_target_timeline = 'latest'
c,按时间点恢复
restore_command = 'cp /usr/local/pgsql/wal-back/%f %p'
recovery_target_time = '2023-03-19 16:16:16.007657+08'
d,
如果不想进入备份模式,直接数据库启动就可以用,那么就使用promote
recovery_target_action:指定在达到恢复目标时服务器采取的动作。
pause:默认值,表示恢复将被暂停
promote:表示恢复结束且服务器将开始接受连接
shutdown:表示在达到恢复目标之后停止服务器。
启动数据库:
[pg1@EULER1 ~]$ pg_ctl -D /usr/local/pgsql/data/ start
waiting for server to start....2023-03-19 21:17:49.399 CST [28172] LOG: starting PostgreSQL 12.5 on x86_64-pc-linux-gnu, compiled by gcc (GCC) 4.8.5 20150623 (EulerOS 4.8.5-28), 64-bit
2023-03-19 21:17:49.400 CST [28172] LOG: listening on IPv4 address "0.0.0.0", port 5432
2023-03-19 21:17:49.400 CST [28172] LOG: listening on IPv6 address "::", port 5432
2023-03-19 21:17:49.405 CST [28172] LOG: listening on Unix socket "/tmp/.s.PGSQL.5432"
2023-03-19 21:17:49.444 CST [28172] LOG: redirecting log output to logging collector process
2023-03-19 21:17:49.444 CST [28172] HINT: Future log output will appear in directory "log".
done
server started
查看数据库状态:
此时的数据库是备份状态,因此,pg_ctl promote即可
[root@EULER1 data]# pg_controldata
pg_control version number: 1201
Catalog version number: 201909212
Database system identifier: 7211655189372047015
Database cluster state: in archive recovery
pg_control last modified: Sun 19 Mar 2023 09:17:49 PM CST
Latest checkpoint location: 0/A000060
Latest checkpoint's REDO location: 0/A000028
或者是进入命令行,执行以下函数即可:
select pg_wal_replay_resume();
最终确认是否恢复正常:
postgres=# \c test
You are now connected to database "test" as user "postgres".
test=# select *from tb_mytps;
i | name
----+--------
1 | name1
2 | name2
3 | name3
4 | name4
5 | name5
8 | name8
9 | name9
10 | name10
6 | name61
7 | name71
(10 rows)
test=# update tb_mytps set name = 'name999' where i = 7;
UPDATE 1
test=# select * from tb_mytps;
i | name
----+---------
1 | name1
2 | name2
3 | name3
4 | name4
5 | name5
8 | name8
9 | name9
10 | name10
6 | name61
7 | name999
(10 rows)
OK,利用pg_basebackup命令归档备份完全成功了。