PostgreSQL PITR实验

磨砺技术珠矶，践行数据之道，追求卓越价值

回到上一级页面： PostgreSQL基础知识与基本操作索引页     回到顶级页面：PostgreSQL索引页

看PostgreSQL中与PITR相关的设定：

 wal_level=archive … # - 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 

开始，在运行之前，看xlog状况：

[postgres@pg201 pgsql]$ ls -lrt ./data/pg_xlog total 32812                            
-rw------- 1 postgres postgres 16777216 Aug  6 14:16 000000010000000000000001 drwx------ 2 postgres postgres     4096 Aug  6 14:16 archive_status -rw------- 1 postgres postgres 16777216 Aug  6 14:16 000000010000000000000002 [postgres@pg201 pgsql]$ [postgres@pg201 pgsql]$ ls -lrt ./arch total 16404                            
-rw------- 1 postgres postgres 16777216 Aug  6 14:16 000000010000000000000001 [postgres@pg201 pgsql]$ 

为文件拷贝进行准备：

[postgres@pg201 pgsql]$ ./bin/psql psql (9.1.2) Type "help" for help. postgres=# select pg_start_backup('gao'); pg_start_backup ----------------- 
 0/3000020 (1 row) postgres=#                 

此时，xlog和archive log状况如下： 

[postgres@pg201 pgsql]$ [postgres@pg201 pgsql]$ ls -lrt ./data/pg_xlog total 49216                            
-rw------- 1 postgres postgres 16777216 Aug 6 14:16 000000010000000000000004 
-rw------- 1 postgres postgres 16777216 Aug 6 14:17 000000010000000000000002 
drwx------ 2 postgres postgres 4096 Aug 6 14:17 archive_status 
-rw------- 1 postgres postgres 16777216 Aug 6 14:17 000000010000000000000003 
                            
[postgres@pg201 pgsql]$ ls -lrt ./arch total 32808                            
-rw------- 1 postgres postgres 16777216 Aug 6 14:16 000000010000000000000001 
-rw------- 1 postgres postgres 16777216 Aug 6 14:17 000000010000000000000002 
[postgres@pg201 pgsql]$                             

完成文件拷贝：

[postgres@pg201 pgsql]$ tar -cvf basedata.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postgres=# select pg_stop_backup(); NOTICE: pg_stop_backup complete, all required WAL segments have been archived pg_stop_backup ---------------- 
 0/30000A0 (1 row) postgres=#                             

再次查看log:

[postgres@pg201 pgsql]$ ls -lrt ./data/pg_xlog total 49220                                
-rw------- 1 postgres postgres 16777216 Aug 6 14:16 000000010000000000000004 
-rw------- 1 postgres postgres 16777216 Aug 6 14:17 000000010000000000000002 
drwx------ 2 postgres postgres 4096 Aug 6 14:20 archive_status 
-rw------- 1 postgres postgres 267 Aug 6 14:20 000000010000000000000003.00000020.backup 
-rw------- 1 postgres postgres 16777216 Aug 6 14:20 000000010000000000000003 
[postgres@pg201 pgsql]$ [postgres@pg201 pgsql]$ ls -lrt ./arch total 49216                                
-rw------- 1 postgres postgres 16777216 Aug 6 14:16 000000010000000000000001
-rw------- 1 postgres postgres 16777216 Aug 6 14:17 000000010000000000000002
-rw------- 1 postgres postgres 267 Aug 6 14:20 000000010000000000000003.00000020.backup 
-rw------- 1 postgres postgres 16777216 Aug 6 14:20 000000010000000000000003 
[postgres@pg201 pgsql]$                                 

可以看到产生了一个backup文件，看内容：

[postgres@pg201 pgsql]$ cat ./data/pg_xlog/000000010000000000000003.00000020.backup START WAL LOCATION: 0/3000020 (file 000000010000000000000003) STOP WAL LOCATION: 0/30000A0 (file 000000010000000000000003) CHECKPOINT LOCATION: 0/3000020            
BACKUP METHOD: pg_start_backup START TIME: 2013-08-06 14:17:53 CST LABEL: gao STOP TIME: 2013-08-06 14:20:53 CST [postgres@pg201 pgsql]$             

强制日志切换，模拟大量数据产生导致日志switch:

postgres=# select pg_switch_xlog(); pg_switch_xlog ---------------- 
 0/4000000 (1 row) postgres=#             

log发生了变化：

[postgres@pg201 pgsql]$ ls -lrt ./data/pg_xlog total 49220                                
-rw------- 1 postgres postgres 16777216 Aug 6 14:20 000000010000000000000006 
-rw------- 1 postgres postgres 267 Aug 6 14:20 000000010000000000000003.00000020.backup 
-rw------- 1 postgres postgres 16777216 Aug 6 14:25 000000010000000000000004 
drwx------ 2 postgres postgres 4096 Aug 6 14:27 archive_status 
-rw------- 1 postgres postgres 16777216 Aug 6 14:27 000000010000000000000005 
[postgres@pg201 pgsql]$ [postgres@pg201 pgsql]$ ls -lrt ./arch total 65620                                
-rw------- 1 postgres postgres 16777216 Aug 6 14:16 000000010000000000000001
-rw------- 1 postgres postgres 16777216 Aug 6 14:17 000000010000000000000002 
-rw------- 1 postgres postgres 267 Aug 6 14:20 000000010000000000000003.00000020.backup 
-rw------- 1 postgres postgres 16777216 Aug 6 14:20 000000010000000000000003 
-rw------- 1 postgres postgres 16777216 Aug 6 14:25 000000010000000000000004 
[postgres@pg201 pgsql]$                                 

再作几次log switch，最后是这样：

[postgres@pg201 pgsql]$ ls -lrt ./data/pg_xlog total 49220                                
-rw------- 1 postgres postgres 16777216 Aug 6 14:20 000000010000000000000006 
-rw------- 1 postgres postgres 267 Aug 6 14:20 000000010000000000000003.00000020.backup 
-rw------- 1 postgres postgres 16777216 Aug 6 14:25 000000010000000000000004 
drwx------ 2 postgres postgres 4096 Aug 6 14:27 archive_status 
-rw------- 1 postgres postgres 16777216 Aug 6 14:27 000000010000000000000005 
[postgres@pg201 pgsql]$ [postgres@pg201 pgsql]$ ls -lrt ./arch total 65620                                
-rw------- 1 postgres postgres 16777216 Aug 6 14:16 000000010000000000000001 
-rw------- 1 postgres postgres 16777216 Aug 6 14:17 000000010000000000000002 
-rw------- 1 postgres postgres 267 Aug 6 14:20 000000010000000000000003.00000020.backup
-rw------- 1 postgres postgres 16777216 Aug 6 14:20 000000010000000000000003
-rw------- 1 postgres postgres 16777216 Aug 6 14:25 000000010000000000000004 
[postgres@pg201 pgsql]$                                 

经过一次正常关机后，日志再次变化：

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

日志变为：

[postgres@pg201 pgsql]$ ls -lrt ./data/pg_xlog total 49220                                
-rw------- 1 postgres postgres 267 Aug 6 14:20 000000010000000000000003.00000020.backup
-rw------- 1 postgres postgres 16777216 Aug 6 14:25 000000010000000000000007 
drwx------ 2 postgres postgres 4096 Aug 6 14:39 archive_status 
-rw------- 1 postgres postgres 16777216 Aug 6 14:39 000000010000000000000006 
-rw------- 1 postgres postgres 16777216 Aug 6 14:39 000000010000000000000005 
[postgres@pg201 pgsql]$ [postgres@pg201 pgsql]$ ls -lrt ./arch total 82024                                
-rw------- 1 postgres postgres 16777216 Aug 6 14:16 000000010000000000000001 
-rw------- 1 postgres postgres 16777216 Aug 6 14:17 000000010000000000000002 
-rw------- 1 postgres postgres 267 Aug 6 14:20 000000010000000000000003.00000020.backup 
-rw------- 1 postgres postgres 16777216 Aug 6 14:20 000000010000000000000003 
-rw------- 1 postgres postgres 16777216 Aug 6 14:25 000000010000000000000004 
-rw------- 1 postgres postgres 16777216 Aug 6 14:39 000000010000000000000005 
[postgres@pg201 pgsql]$                                 

重新启动PostgreSQL，添加数据，然后杀掉进程，模拟崩溃：

[postgres@pg201 pgsql]$ ./bin/psql psql (9.1.2) Type "help" for help. postgres=# create table test(id integer); CREATE TABLE postgres=# insert into test values(1); INSERT 0 1 postgres=# \q [postgres@pg201 pgsql]$ 

[root@pg201 ~]# ps -ef | grep post root 3120  3049  0 14:08 pts/1    00:00:00 su - postgres postgres 3121  3120  0 14:08 pts/1    00:00:00 -bash root 3216  3191  0 14:15 pts/2    00:00:00 su - postgres postgres 3217  3216  0 14:15 pts/2    00:00:00 -bash root 3299  3279  0 14:17 pts/3    00:00:00 su - postgres postgres 3300  3299  0 14:17 pts/3    00:00:00 -bash postgres 3516     1  0 15:00 pts/2    00:00:00 /usr/local/pgsql/bin/postgres -D ./data postgres 3518  3516  0 15:00 ?        00:00:00 postgres: writer process postgres 3519  3516  0 15:00 ?        00:00:00 postgres: wal writer process postgres 3520  3516  0 15:00 ?        00:00:00 postgres: autovacuum launcher process postgres 3521  3516  0 15:00 ?        00:00:00 postgres: archiver process postgres 3522  3516  0 15:00 ?        00:00:00 postgres: stats collector process root 3559  3535  0 15:01 pts/4    00:00:00 grep post [root@pg201 ~]# kill -s SIGQUIT 3516
[root@pg201 ~]# 

下面开始回复动作、找出基础备份：

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

其pg_xlog目录下，还是旧的online redo log:

[postgres@pg201 pg_xlog]$ ls -lrt total 49216
-rw------- 1 postgres postgres 16777216 Aug 6 14:16 000000010000000000000004
-rw------- 1 postgres postgres 16777216 Aug 6 14:17 000000010000000000000002
drwx------ 2 postgres postgres 4096 Aug 6 14:17 archive_status
-rw------- 1 postgres postgres 16777216 Aug 6 14:17 000000010000000000000003
[postgres@pg201 pg_xlog]$ 

把它清空后，不补足online redolog，仅仅用 archive log的效果：

在解压好的data目录下，建立 recovery.conf文件：

[postgres@pg201 data]$ cat recovery.conf restore_command = 'cp /usr/local/pgsql/arch/%f %p'
[postgres@pg201 data]$ 

启动PostgreSQL：

[postgres@pg201 pgsql]$ ./bin/pg_ctl -D ./data status pg_ctl: no server running [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 2013-08-06 14:17:53 CST LOG:  creating missing WAL directory "pg_xlog/archive_status" LOG: starting archive recovery LOG:  restored log file "000000010000000000000003" from archive LOG:  redo starts at 0/3000078
LOG:  consistent recovery state reached at 0/4000000
LOG:  restored log file "000000010000000000000004" from archive LOG:  restored log file "000000010000000000000005" from archive cp: cannot stat `/usr/local/pgsql/arch/000000010000000000000006': No Such File or Directory LOG: could not open file "pg_xlog/000000010000000000000006" (log file 0, segment 6): No Such File or Directory

LOG: redo done at 0/5000078 LOG: restored log file "000000010000000000000005" from archive 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

因为我的创建table test 的动作虽然计入了 redo log中，但是由于突然的崩溃，没有来得及放入archive 日志中，所以，没有得到恢复：

[postgres@pg201 pgsql]$ ./bin/psql psql (9.1.2) Type "help" for help. postgres=# select * from test; ERROR: relation "test" does not exist LINE 1: select * from test; ^ postgres=# 

此时，看Log，就可以清晰地看到TimeLine的痕迹了：

[postgres@pg201 pgsql]$ ls -lrt ./data/pg_xlog total 49220
-rw------- 1 postgres postgres 56 Aug 6 15:11 00000002.history
-rw------- 1 postgres postgres 16777216 Aug 6 15:11 000000020000000000000005
-rw------- 1 postgres postgres 16777216 Aug 6 15:17 000000020000000000000006
drwx------ 2 postgres postgres 4096 Aug 6 15:17 archive_status
-rw------- 1 postgres postgres 16777216 Aug 6 15:17 000000020000000000000007
[postgres@pg201 pgsql]$ 

[postgres@pg201 pgsql]$ ls -lrt ./arch total 114836
-rw------- 1 postgres postgres 16777216 Aug 6 14:16 000000010000000000000001
-rw------- 1 postgres postgres 16777216 Aug 6 14:17 000000010000000000000002
-rw------- 1 postgres postgres 267 Aug 6 14:20 000000010000000000000003.00000020.backup
-rw------- 1 postgres postgres 16777216 Aug 6 14:20 000000010000000000000003
-rw------- 1 postgres postgres 16777216 Aug 6 14:25 000000010000000000000004
-rw------- 1 postgres postgres 16777216 Aug 6 14:39 000000010000000000000005
-rw------- 1 postgres postgres 56 Aug 6 15:11 00000002.history
-rw------- 1 postgres postgres 16777216 Aug 6 15:17 000000020000000000000006
-rw------- 1 postgres postgres 16777216 Aug 6 15:17 000000020000000000000005
[postgres@pg201 pgsql]$ cat ./arch/00000002.history 1       000000010000000000000005 no recovery target specified [postgres@pg201 pgsql]$ 

这次再看清空pg_xlog目录后，补足online redolog+archive log的效果：

还要把 pg_xlog/archive_status 目录清空：

[postgres@pg201 pgsql]$ cp ./data.bak/pg_xlog/* ./data/pg_xlog/ ... [postgres@pg201 pg_xlog]$ ls -lrt total 98432 -rw------- 1 postgres postgres 16777216 Aug 6 14:16 000000010000000000000004 -rw------- 1 postgres postgres 16777216 Aug 6 14:17 000000010000000000000002 -rw------- 1 postgres postgres 16777216 Aug 6 14:17 000000010000000000000003 -rw------- 1 postgres postgres 267 Aug 6 15:41 000000010000000000000003.00000020.backup -rw------- 1 postgres postgres 16777216 Aug 6 15:41 000000010000000000000007 -rw------- 1 postgres postgres 16777216 Aug 6 15:41 000000010000000000000006 -rw------- 1 postgres postgres 16777216 Aug 6 15:41 000000010000000000000005 drwx------ 2 postgres postgres 4096 Aug 6 15:44 archive_status [postgres@pg201 pg_xlog]$ 

此时，启动 PostgreSQL:

[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 2013-08-06 14:17:53 CST LOG: starting archive recovery LOG:  restored log file "000000010000000000000003" from archive LOG:  redo starts at 0/3000078
LOG:  consistent recovery state reached at 0/4000000
LOG:  restored log file "000000010000000000000004" from archive LOG:  restored log file "000000010000000000000005" from archive cp: cannot stat `/usr/local/pgsql/arch/000000010000000000000006': No such file or directory LOG: record with zero length at 0/6011770 LOG: redo done at 0/6011730 LOG: last completed transaction was at log time 2013-08-06 15:01:17.757945+08 LOG: restored log file "00000002.history" from archive cp: cannot stat `/usr/local/pgsql/arch/00000003.history': No such file or directory LOG:  selected new timeline ID: 3 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

看数据：

[postgres@pg201 pgsql]$ ./bin/psql psql (9.1.2) Type "help" for help. postgres=# select * from test; id ----
  1 (1 row) postgres=# 

回到上一级页面： PostgreSQL基础知识与基本操作索引页     回到顶级页面：PostgreSQL索引页

磨砺技术珠矶，践行数据之道，追求卓越价值