这是因为一些数据库被配置为会杀掉长时间空闲的连接，网络或数据库相关的异常也可能会杀死连接。
This is because some databases are configured to kill long idle connections and a network or database related exception may also kill a connection.
然后参与者做它们需要做的任何事情，如把结果写为真正的数据库数据或进行一些其它优化。
The participants can then do whatever they need to do, such as perhaps writing the results to the real database data or some other optimizations they might devise.
为便于演示，我将向数据库再添加一些文档。
For demonstration purposes, I'll add some more documents to the database.
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