在mongodb中限制集合中的文档数 [英] Limit the number of documents in a collection in mongodb

问题描述

我有一个用作缓存的集合.如何在此馆藏中将文件数限制为5M. 注意:可以更新的缓存项将存在于缓存中. 我曾经尝试使用上限，但是保存在上限集合中的项目无法修改.

I have a collection that use as a cache. How can I limit the documents number to 5M inside this collection. Note: that the cache item can be updated will existing in the cache. I use tried to use capped, but the item saves in a capped collection cannot be modified.

有没有办法做到这一点? (我想避免删除该项，然后插入更新项)

Is there a way to do that? (i would like to avoid delete the item and then insert the update one)

推荐答案

不幸的是，您在这里没有什么可以做的.如您所述，无法修改上限集合中的文档.而且，您不能在文档中指定限制，以IIRC为单位，以兆字节为单位.

Unfortunately, there's not much you can do here. As you noted, documents in capped collections can't be modified. And also, you can't specify a limit in documents, it's in megabytes, IIRC.

因此，最好的选择是使用常规收集并定期进行工作，以检查收集是否溢出并清理旧文档.

So, your best bet is to use normal collection and have a periodic job that'll check the collection for overflows and will clean up old documents.

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