postgresql 备份恢复(二)

Postgre SQL 2020-06-18

postgresql同样支持在线备份,该备份方式与oracle中用户热备的方式相同,手动拷贝数据文库文件与归档日志。可以根据测试过程将备份直接写成script,通过定制,完成数据库的自动备份。
postgresql的恢复支持基于时间戳与事务ID,可以通过时间戳或事务ID的方式,完成数据库的不完全恢复或者因错误操作的故障恢复。
该测试目的：postgresql的在线备份;通过在线备份完成恢复。

1,开启归档

  
  
   
   [postgre@daduxiong ~]$ more /usr/local/pgsql/data/postgresql.conf |grep archive_ archive_mode = on # allows archiving to be done archive_command = 'cp -i %p /archive/%f >/dev/null'

2,重新启动数据库

[root@daduxiong ~]# service postgresql stop Stopping Postgresql: server stopped ok [root@daduxiong ~]# service postgresql start Starting Postgresql: ok

3,启动备份

[postgre@daduxiong archive]$ psql postgres -c "select pg_start_backup('hot_backup');" pg_start_backup ----------------- 0/7000020 (1 row)

4,使用tar命令备份数据库文件,不包含pg_xlog目录

[postgre@daduxiong archive]$ tar --exclude $PGDATA/pg_xlog -cvjpf /archive/pgbackup.tar.bz2 $PGDATA

5,完成备份

[postgre@daduxiong archive]$ psql postgres -c "select pg_stop_backup();" pg_stop_backup ---------------- 0/70133A0 (1 row)

说明: 调用select pg_start_backup('xxx');开始备份时，数据库释放对数据目录中各文件的锁，使其它进程可以进行操作，此时用户对数据库的操作，都缓存在数据缓冲区中，当调用select pg_stop_backup();时,数据缓冲区中的数据刷写到磁盘，终止备份模式，并执行自动切换到下一个WAL段。

6,在postgres数据库中创建表并插入记录,作为恢复时的判断。

代码

   
   
    
    [postgre@daduxiong archive]$ psql postgres Welcome to psql 8.3.10,the Postgresql interactive terminal. Type: \copyright for distribution terms \h for help with sql commands \? for help with psql commands \g or terminate with semicolon to execute query \q to quit postgres=# create table abc(id integer); CREATE TABLE postgres=# insert into abc values(1); INSERT 0 1 postgres=# \q

7,此时假设数据库出现问题,停止数据库,拷贝日志

[root@daduxiong pgsql]# service postgresql stop Stopping Postgresql: server stopped ok [postgre@daduxiong archive]$ cp $PGDATA/pg_xlog/*00* /archive/

8,删除"发生错误"的data目录

[root@daduxiong pgsql]# rm -rf data

9,解压之前的备份文件压缩包

代码

   
   [postgre@daduxiong pgsql]$ tar -xvf /archive/pgbackup.tar.bz2 ....省略 /usr/local/pgsql/data/global/2843 /usr/local/pgsql/data/postmaster.opts /usr/local/pgsql/data/pg_twophase/ /usr/local/pgsql/data/postmaster.pid /usr/local/pgsql/data/backup_label /usr/local/pgsql/data/PG_VERSION

10,恢复data目录,重新创建pg_xlog目录及其子目录archive_status

代码

   
   [root@daduxiong pgsql]# mv /archive/usr/local/pgsql/data /usr/local/pgsql [root@daduxiong data]# mkdir pg_xlog [root@daduxiong data]# chmod 0700 pg_xlog/ [root@daduxiong data]# chown postgre:postgre pg_xlog/ [root@daduxiong data]# cd pg_xlog/ [root@daduxiong pg_xlog]# mkdir archive_status [root@daduxiong pg_xlog]# chmod 0700 archive_status/ [root@daduxiong pg_xlog]# chown postgre:postgre archive_status/ [root@daduxiong pg_xlog]# mv /archive/*00* /usr/local/pgsql/data/pg_xlog [root@daduxiong pg_xlog]# cd .. [root@daduxiong data]# ls backup_label pg_clog pg_multixact pg_twophase postgresql.conf base pg_hba.conf pg_subtrans PG_VERSION postmaster.opts global pg_ident.conf pg_tblspc pg_xlog postmaster.pid

11,配置恢复配置文件

代码

   
   [root@daduxiong data]# touch recovery.conf [root@daduxiong data]# echo "restore_command='cp -i /archive/%f %p'" >>recovery.conf [root@daduxiong data]# chown postgre:postgre recovery.conf [root@daduxiong data]# chmod 0750 recovery.conf

12,启动数据库,观察数据库启动的日志

代码

   
   [root@daduxiong data]# service postgresql start Starting Postgresql: ok ---省略日志部分内容 LOG: selected new timeline ID: 3 LOG: restored log file "00000002.history" from archive LOG: archive recovery complete LOG: autovacuum launcher started LOG: database system is ready to accept connections cp: overwrite `/archive/000000010000000000000008'? cp: overwrite `/archive/000000010000000000000009'? cp: overwrite `/archive/000000020000000000000009'? cp: overwrite `/archive/00000002000000000000000A'?

13,验证恢复结果。检查之前创建的表与记录。

代码

   
   sql interactive terminal. Type: \copyright for distribution terms \h for help with sql commands \? for help with psql commands \g or terminate with semicolon to execute query \q to quit postgres=# select * from abc; id ---- 1 (1 row) postgres=# \q [root@daduxiong data]# ls -l total 80 -rw------- 1 postgre postgre 147 Aug 31 10:26 backup_label.old drwx------ 6 postgre postgre 4096 Aug 27 11:33 base drwx------ 2 postgre postgre 4096 Aug 31 10:41 global drwx------ 2 postgre postgre 4096 Aug 10 11:06 pg_clog -rwx------ 1 postgre postgre 3429 Aug 10 11:10 pg_hba.conf -rwx------ 1 postgre postgre 1460 Aug 10 11:06 pg_ident.conf drwx------ 4 postgre postgre 4096 Aug 10 11:06 pg_multixact drwx------ 2 postgre postgre 4096 Aug 10 11:06 pg_subtrans drwx------ 2 postgre postgre 4096 Aug 10 11:06 pg_tblspc drwx------ 2 postgre postgre 4096 Aug 10 11:06 pg_twophase -rwx------ 1 postgre postgre 4 Aug 10 11:06 PG_VERSION drwx------ 3 postgre postgre 4096 Aug 31 10:35 pg_xlog -rwx------ 1 postgre postgre 16727 Aug 31 09:42 postgresql.conf -rwx------ 1 postgre postgre 59 Aug 31 10:35 postmaster.opts -rw------- 1 postgre postgre 47 Aug 31 10:35 postmaster.pid -rwxr-x--- 1 postgre postgre 39 Aug 31 10:34 recovery.done