PostgreSQL的 PITR實戰---運用 recovery_target_time

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看了很多的例子，沒有發現具體講 recovery_target_time的例子，於是自己作一個吧

在開始之前，先把postgresql.conf的配置設置好：

 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                                            

然后啟動PostgreSQL：

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

在開始備份前，先作一條數據：此時，時間大約是13：40之前：

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

然后開始進行基礎備份：

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

tar命令打包：

tar -cvf ./base.tar ./data

結束基礎備份：

postgres=# select pg_stop_backup(); NOTICE: pg_stop_backup complete, all required WAL segments have been archived pg_stop_backup ---------------- 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

此時大約是13：40左右，再插入一條數據：

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

等待，到13：50左右，再插入一條數據：

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

為了方便操作，進行一次強制的日志切換：

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

現在，模擬崩潰，強制殺掉進程：

[root@pg201 ~]# kill -s SIGQUIT Postmaster進程號                        

然后，原有data目錄改名保存，開始恢復過程：

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

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

把崩潰時后的online wal log 也准備好：

[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]$ 

作一個 recovery.conf文件，指明要恢復到13：45，也就是200數據已經出現，300數據尚未插入的時候

[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]$ 

再次啟動PostgreSQL，發生了恢復：

[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 

驗證：

[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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磨礪技術珠磯，踐行數據之道，追求卓越價值