PostgreSQL没有类似MySQL的二进制日志，但是有和MySQL类似的REDOLOG，并且有MySQL没有的REDO归档功能。当然REDO的归档已经MariaDB和Percona-MySQL已经实现。那我
PostgreSQL 没有类似MySQL 的二进制日志， 但是有和MySQL 类似的REDO LOG，并且有MySQL 没有的REDO 归档功能。当然REDO 的归档已经MariaDB 和Percona-MySQL 已经实现。
那我们就利用PGSQL的REDO 归档，也叫WAL来实现增量备份。
假设我们已经做了一个物理的全备，并且相应的参数都已经设置完毕，比如以下：
那么关于WAL归档日志要注意的一点是，如果CRASH 掉了，那么没有归档的XLOG也可能没有提交到数据文件，，所以有可能这部分数据会丢失掉。所以在之后恢复的时候我们要把这部分XLOG拷贝到全备的对应目录。
恢复方法：
1. 确保没有任何业务对PG服务进行访问。(有可能这个时候PG已经CRASH掉了。) 2. 先停掉POSTGRESQL 服务。 3. cd /home/pgsql; 4. mv data data_old 6. cp -rfp /home/full_backup/* /home/pgsql （拷贝全备） 7. cp -rfp data_old/pg_xlog/000* data/pg_xlog/ （这里是拷贝自从最后一个增量和系统CRASH之间的XLOG到对应的目录。） 8. cd data 9. vi recovery.conf （添加recovery.conf文件，让PG认为这次是在恢复。） restore_command='test ! -f /home/increment_log/%f && cp /home/increment_log/%f %p' recovery_target_timeline = 'latest' 10. chown -R postgres.postgres recovery.conf 11. 启动postgresql 服务即可。如果正确恢复了，那么recovery.conf 会自动更名为recovery.done.
以我的机器为例，我的版本是9.3，PG_XLOG中看到的BACKUP 信息：
[root@postgresql-instance pg_xlog]# cat 000000010000000000000003.00000028.backup START WAL LOCATION: 0/3000028 (file 000000010000000000000003) STOP WAL LOCATION: 0/30000B8 (file 000000010000000000000003) CHECKPOINT LOCATION: 0/3000028 BACKUP METHOD: pg_start_backup BACKUP FROM: master START TIME: 2014-01-07 03:35:02 EST LABEL: ytt STOP TIME: 2014-01-07 03:36:27 EST日志中会看到恢复如下恢复信息：
LOG: 00000: starting archive recovery LOCATION: StartupXLOG, xlog.c:4983 LOG: 00000: redo starts at 0/3000028 LOCATION: StartupXLOG, xlog.c:5531 LOG: 00000: consistent recovery state reached at 0/303FC88本文出自 “上帝，咱们不见不散！” 博客，请务必保留此出处
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