Python 按时间戳对 mongodb 文档进行排序（按降序排列）
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sort mongodb documents by timestamp (in desc order)
提问by jisu
I have a bunch of documents in mongodb and all have a timestamp field with timestamp stored as "1404008160". I want to sort all docs in this collection by desc order. I do it by:
我在 mongodb 中有一堆文档，并且都有一个时间戳字段，时间戳存储为“1404008160”。我想按降序对这个集合中的所有文档进行排序。我这样做：
sort = [('timestamp', DESCENDING)]
collection.find(limit=10).sort(sort)
However, I don't get results sorted by timestamp in desc order. I am thinking it's because timestamp is being treated as an int field. Is there a work around this without changing data type of timestamp field. I already have a lot of data in this collection so don't want to go through the hassle of import/export, etc.
但是，我没有得到按降序按时间戳排序的结果。我认为这是因为时间戳被视为 int 字段。在不更改时间戳字段的数据类型的情况下是否有解决此问题的方法。我在这个集合中已经有很多数据，所以不想经历导入/导出等的麻烦。
Also - I want to keep the load for sorting to mongodb rather than doing it programmatically in python.
另外 - 我想保持对 mongodb 进行排序的负载，而不是在 python 中以编程方式进行。
To be clear: Timestamp does not indicate when the document was created and it is stored as string (e.g. "1404217646").
需要明确的是：时间戳不指示文档的创建时间，而是存储为字符串（例如“1404217646”）。
Thanks in advance.
提前致谢。
回答by Martin Konecny
Assuming your timestamp indicates when the document was created, you can use _idinstead.
假设您的时间戳指示文档的创建时间，您可以_id改用.
_idObjectId in mongo stores your timestamp. Try the following:
_idmongo 中的 ObjectId 存储您的时间戳。请尝试以下操作：
sort = {'_id': -1}
collection.find({}, limit=10).sort(sort)
If you still want to sort by your custom timestampfield, the following should work:
如果您仍想按自定义timestamp字段排序，则应执行以下操作：
sort = {'timestamp': -1}
collection.find({}, limit=10).sort(sort)
Note that this is assuming all of your timestampfields are of the same type (string, int)
请注意，这是假设您的所有timestamp字段都属于相同类型 ( string, int)
回答by Mulagala
You can sort your collection in descending order by using sort( { 'timestamp': -1 } ).Your query will be like this
您可以使用降序对您的集合进行排序。您的sort( { 'timestamp': -1 } )查询将是这样的
collection.find().sort( { 'timestamp': -1 } ).limit(10)
If you have sql knowledge, you can compare both queries in the following link
如果你有sql知识，你可以在下面的链接中比较这两个查询
