PostgreSQL 9.3 add functions pg_is_in_backup() and pg_backup_start_time() report the status of base backups

Add SQL functions pg_is_in_backup() and pg_backup_start_time() (Gilles Darold)

These functions report the status of base backups.

这两个函数可用于查看当前数据库是否在备份, 以及开始备份的时间.

[测试]

postgres=# select pg_start_backup(now()::text),now();
 pg_start_backup |              now
-----------------+-------------------------------
 2/54000028      | 2013-05-08 15:55:00.267025+08
(1 row)

postgres=# select pg_is_in_backup();
 pg_is_in_backup
-----------------
 t
(1 row)

postgres=# select pg_backup_start_time();
  pg_backup_start_time
------------------------
 2013-05-09 05:55:00+08
(1 row)

postgres=# select pg_stop_backup();
NOTICE:  pg_stop_backup complete, all required WAL segments have been archived
 pg_stop_backup
----------------
 2/540000F0
(1 row)

postgres=# select pg_backup_start_time();
 pg_backup_start_time
----------------------

(1 row)

postgres=# select pg_is_in_backup();
 pg_is_in_backup
-----------------
 f
(1 row)

[参考]

1. http://git.postgresql.org/gitweb/?p=postgresql.git;a=commit;h=68de499bda40fdf1395b714bb63febad61046700

2. http://www.postgresql.org/docs/devel/static/functions-admin.html#FUNCTIONS-ADMIN-BACKUP