相当于mongodb中的“select distinct on”

Question

我想知道mongodb 是否具有与select distinct on 等价的函数，如sql。 例如，如果我在Sql 中有此查询：

SELECT DISTINCT ON (department) * FROM employees
ORDER BY department, salary DESC;

我怎样才能在mongodb 中做同样的query？ 对于mongodb，我使用python 和pymongo

Answer 1

https://docs.mongodb.com/manual/reference/method/db.collection.distinct/

使用db.collection.distinct(field, query, options)

https://pymongo.readthedocs.io/en/stable/api/pymongo/collection.html?highlight=distinct#pymongo.collection.Collection.distinct

https://api.mongodb.com/python/1.9/api/pymongo/collection.html#pymongo.collection.Collection.distinct