PostgreSQL的 PITR实战---运用 recovery_target_time

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看了很多的例子，没有发现具体讲 recovery_target_time的例子，于是自己作一个吧

在开始之前，先把postgresql.conf的配置设置好：

 wal_level = archive # minimal, archive, or hot_standby # (change requires restart) # - Archiving - archive_mode = on               # allows archiving to be done # (change requires restart) 
 archive_command = 'cp %p /usr/local/pgsql/arch/%f' # command to use to archive a logfile segment #archive_timeout = 0 # force a logfile segment switch after this # number of seconds; 0 disables                                            

然后启动PostgreSQL：

[postgres@pg201 pgsql]$ ./bin/pg_ctl -D ./data start

在开始备份前，先作一条数据：此时，时间大约是13：40之前：

postgres=# create table test(id integer); CREATE TABLE postgres=# insert into test values(100); INSERT 0 1                

然后开始进行基础备份：

postgres=# select pg_start_backup('gao'); pg_start_backup ----------------- 
 0/2000020 (1 row)                

tar命令打包：

tar -cvf ./base.tar ./data

结束基础备份：

postgres=# select pg_stop_backup(); NOTICE: pg_stop_backup complete, all required WAL segments have been archived pg_stop_backup ---------------- 
 0/20000A0 (1 row)                

此时大约是13：40左右，再插入一条数据：

postgres=# insert into test values(200); INSERT 0 1                

等待，到13：50左右，再插入一条数据：

postgres=# insert into test values(300); INSERT 0 1                

为了方便操作，进行一次强制的日志切换：

postgres=# select pg_switch_xlog(); pg_switch_xlog ---------------- 
 0/30002A0 (1 row) postgres=#                 

现在，模拟崩溃，强制杀掉进程：

[root@pg201 ~]# kill -s SIGQUIT Postmaster进程号                        

然后，原有data目录改名保存，开始恢复过程：

[postgres@pg201 pgsql]$ mv ./data ./data.bak

[postgres@pg201 pgsql]$ tar -xvf base.tar ./data                    

把崩溃时后的online wal log 也准备好：

[postgres@pg201 pgsql]$ rm -rf ./data/pg_xlog [postgres@pg201 pgsql]$ cp -r ./data.bak/pg_xlog/ ./data [postgres@pg201 pgsql]$ cd ./data/pg_xlog [postgres@pg201 pg_xlog]$ [postgres@pg201 archive_status]$ pwd                    
/usr/local/pgsql/data/pg_xlog/archive_status [postgres@pg201 archive_status]$ rm -f * [postgres@pg201 archive_status]$ 

作一个 recovery.conf文件，指明要恢复到13：45，也就是200数据已经出现，300数据尚未插入的时候

[postgres@pg201 data]$ pwd                        
/usr/local/pgsql/data [postgres@pg201 data]$ cat recovery.conf restore_command = 'cp /usr/local/pgsql/arch/%f %p' recovery_target_time = '2013-08-07 13:45:00+08' [postgres@pg201 data]$ 

再次启动PostgreSQL，发生了恢复：

[postgres@pg201 pgsql]$ ./bin/pg_ctl -D ./data start pg_ctl: another server might be running; trying to start server anyway server starting [postgres@pg201 pgsql]$ LOG: database system was interrupted; last known up at 2013-08-07 13:39:51 CST LOG: starting point-in-time recovery to 2013-08-07 13:45:00+08 LOG: restored log file "000000010000000000000002" from archive LOG: redo starts at 0/2000078 LOG: consistent recovery state reached at 0/3000000 LOG: restored log file "000000010000000000000003" from archive LOG: recovery stopping before commit of transaction 1685, time 2013-08-07 13:51:05.407695+08 LOG: redo done at 0/3000240 LOG: last completed transaction was at log time 2013-08-07 13:40:44.338862+08                                        
cp: cannot stat `/usr/local/pgsql/arch/00000002.history': No such file or directory 
LOG:  selected new timeline ID: 2                                        
cp: cannot stat `/usr/local/pgsql/arch/00000001.history': No such file or directory 
LOG: archive recovery complete LOG: autovacuum launcher started LOG: database system is ready to accept connections 

验证：

[postgres@pg201 ~]$ cd /usr/local/pgsql [postgres@pg201 pgsql]$ ./bin/psql psql (9.1.2) Type "help" for help. postgres=# select * from test; id -----
 100
 200 (2 rows) postgres=# \q

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磨砺技术珠矶，践行数据之道，追求卓越价值