如何锁定表格进行写入 [英] how to lock a table for writing

问题描述

我想在一段时间内锁定一个表以进行写入，同时使其可供读取。
可能吗？
理想情况下，我想用谓词锁定表（例如，防止写行 where country = France ）。

I would like to lock a table for writing during a period of time, while leaving it available for reading. Is that possible ? Ideally I would like to lock the table with a predicate (for example prevent writing rows "where country = france").

推荐答案

如果您真的想针对此类插入内容锁定，即查询应该挂起并且仅在允许时继续执行，在表上放置 SHARE 锁并保持交易打开。

If you really want to lock against such inserts, i.e. the query should hang and only continue when you allow it, you would have to place a SHARE lock on the table and keep the transaction open.

通常这不是一个好主意。

This is usually not a good idea.

如果要防止插入任何此类插入，即尝试插入时抛出错误，请创建插入前触发器，如果​​ NEW 行满足条件，则会引发异常。

If you want to prevent any such inserts, i.e. throw an error when such an insert is attempted, create a BEFORE INSERT trigger that throws an exception if the NEW row satisfies the condition.

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