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

如果你想删除一个“database is locked”错误,请按照以下步骤执行:

将数据库文件复制到其他位置。 用复制的数据库替换数据库。这将解除对访问数据库文件的所有进程的引用。

其他回答

我在多线程应用程序中也有“数据库被锁定”错误,这似乎是SQLITE_BUSY结果代码,我通过将sqlite3_busy_timeout设置为适当的长度(如30000)来解决这个问题。

(顺便说一句,对于一个7年前的问题,居然没有人发现这一点,这真奇怪!SQLite真的是一个奇特而神奇的项目…)

我导致我的sqlite数据库在写入过程中崩溃一个应用程序而被锁定。以下是我如何修复它:

echo ".dump" | sqlite old.db | sqlite new.db

摘自:http://random.kakaopor.hu/how-to-repair-an-sqlite-database

我添加了“池=true”连接字符串,它工作。

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。

我的Linux环境上的lsof命令帮助我弄清楚一个进程挂起并保持文件打开。 终止了这个过程,问题就解决了。