当我输入这个查询: 删除邮件中id = 71的所有邮件
SQLite返回以下错误:
SQL error: database is locked
我如何解锁数据库,以便这个查询将工作?
当我输入这个查询: 删除邮件中id = 71的所有邮件
SQLite返回以下错误:
SQL error: database is locked
我如何解锁数据库,以便这个查询将工作?
当前回答
在选择重新启动选项之前,有必要看看能否找到sqlite数据库的用户。
在Linux上,可以使用fuser:
$ fuser database.db
$ fuser database.db-journal
在我的案例中,我得到了如下的回应:
philip 3556 4700 0 10:24 pts/3 00:00:01 /usr/bin/python manage.py shell
这表明我有另一个使用数据库的pid 3556 (manage.py)的Python程序。
其他回答
我刚刚遇到了类似的情况——我的web应用程序能够从数据库中读取数据,但不能执行任何插入或更新。重启Apache至少暂时解决了这个问题。
不过,如果能找到根本原因就好了。
删除-journal文件听起来是个糟糕的主意。它允许sqlite在崩溃后将数据库回滚到一致的状态。如果在数据库处于不一致状态时删除它,则会留下一个损坏的数据库。引用sqlite站点的一个页面:
If a crash or power loss does occur and a hot journal is left on the disk, it is essential that the original database file and the hot journal remain on disk with their original names until the database file is opened by another SQLite process and rolled back. [...] We suspect that a common failure mode for SQLite recovery happens like this: A power failure occurs. After power is restored, a well-meaning user or system administrator begins looking around on the disk for damage. They see their database file named "important.data". This file is perhaps familiar to them. But after the crash, there is also a hot journal named "important.data-journal". The user then deletes the hot journal, thinking that they are helping to cleanup the system. We know of no way to prevent this other than user education.
The rollback is supposed to happen automatically the next time the database is opened, but it will fail if the process can't lock the database. As others have said, one possible reason for this is that another process currently has it open. Another possibility is a stale NFS lock, if the database is on an NFS volume. In that case, a workaround is to replace the database file with a fresh copy that isn't locked on the NFS server (mv database.db original.db; cp original.db database.db). Note that the sqlite FAQ recommends caution regarding concurrent access to databases on NFS volumes, because of buggy implementations of NFS file locking.
我无法解释为什么删除一个-journal文件会让你锁定一个数据库,而你以前不能。这是可复制的吗?
顺便说一下,-journal文件的存在并不一定意味着发生了崩溃或有要回滚的更改。Sqlite有几种不同的日志模式,在PERSIST或TRUNCATE模式下,它始终保留-journal文件,并更改内容以指示是否有要回滚的部分事务。
如果文件位于远程文件夹(如共享文件夹)中,则可能引发此错误。我将数据库更改为本地目录,它工作得很好。
在windows中,您可以尝试这个程序http://www.nirsoft.net/utils/opened_files_view.html,以找出进程正在处理db文件。尝试关闭该程序解锁数据库
在Linux和macOS中,你可以做类似的事情,例如,如果你锁定的文件是development.db:
$ fuser development.db
这个命令将显示哪个进程正在锁定该文件:
> development.db: 5430
只需终止进程……
杀死-9 5430
...您的数据库将被解锁。
我有一个工具“DB Browser for SQLite”正在运行,也在里面工作。显然,这个工具也会锁上东西。 在点击“写入更改”或“恢复更改”后,锁消失了,另一个进程(一个React-Native脚本)不再给出这个错误。