MongoDB：如何使用IS NOT（MAX（））标准查询文档？

Question

This is a collection called test .

{
    {"_id": 1, "groupName": "A", lastModified: ISODate("2012-09-17T23:25:56.314Z")},
    {"_id": 2, "groupName": "A", lastModified: ISODate("2013-09-17T23:25:56.314Z")},
    {"_id": 3, "groupName": "A", lastModified: ISODate("2016-01-10T23:25:56.314Z")},
    {"_id": 4, "groupName": "B", lastModified: ISODate("2020-09-17T23:25:56.314Z")},
    {"_id": 5, "groupName": "B", lastModified: ISODate("2000-01-17T23:25:56.314Z")}
}

I want to query some documents within this collection, with these criteria:

1. whose groupName are "A".
2. whose lastModified are not the greatest value( ISODate("2016-01-10T23:25:56.314Z") ) of the lastModified fields of the documents with "groupName": "A" .

So in this case, the result should be

{
    {"_id": 1, "groupName": "A", lastModified: ISODate("2012-09-17T23:25:56.314Z")},
    {"_id": 2, "groupName": "A", lastModified: ISODate("2013-09-17T23:25:56.314Z")}
}

I'm using Node.js with node-mongodb-native module. Can I do it without fetching and iterating over the entire documents? I mean, can I do it within DB?

Answer 1

If you'll definitely filter by groupName, this simple query can help you achieve your desired result without much performance overhead.

db.test.find({groupName : "A"}).skip(1).sort({lastModifiedAt : -1})

If you have a more complex scenario/grouping/nesting however, you might need to use aggregate or mapReduce framework.