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How do I get the last element in MongoDB?
To find last object in collection, at first sort() to sort the values. Use limit() to get number of values i.e. if you want only the last object, then use limit(1).
Where is latest record in MongoDB?
To get last inserted document, use sort() along with limit(1).
Where is long running query in MongoDB?
The db. currentOp() method reports in-progress operations on your mongod process. In other words, it will return information on all active operations running on your instance. This allows you to quickly identify long-running and/or blocking operations and focus your attention on problematic areas.
What is $$ root in MongoDB?
$$ROOT. The $$ROOT variable contains the source documents for the group. If you’d like to just pass them through unmodified, you can do this by $pushing $$ROOT into the output from the group.
Why is MongoDB slow?
The slow queries can happen when you do not have proper DB indexes. Without indexes, MongoDB must perform a collection scan, i.e. scan every document in a collection, to select those documents that match the query statement. And it can take a while if you have many documents in your collection.
How to get the last N Records in MongoDB?
If you use the auto created _id field it has a date embedded in it so you can use that to order by That will return back all your documents sorted from oldest to newest. You can also use a Natural Order mentioned above
When to use a query object in MongoDB?
When finding documents in a collection, you can filter the result by using a query object. The first argument of the find () method is a query object, and is used to limit the search. Run “demo_mongodb_query.js”
When to use the first and last operator in MongoDB?
The following aggregation uses the $first and $last operator on the log array to retrieve the information for the first run and the last run: The operation returns the following results:
What does natural mean in MongoDB command line?
I need a query with constant time response. If there is any better mongodb command line query, do let me know. This is a rehash of the previous answer but it’s more likely to work on different mongodb versions. $natural:-1 means order opposite of the one that records are inserted in.