Questions

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1How to Connect to MongoDB server from Node.js application?

2How to create/ insert a record in MongoDB via Node.js?

3How to read records in MongoDB via Node.js?

4What is Query Selectors/Query Operators?

5What is Projection Operators?

6How can we modify documents?

7How do we update arrays in the MongoDB documents?

8How do we Insert or Update in a Single Operation?

9How do we delete documents in a collection?

10How would you handle a 'Bulk Write' failure mid-way through 10,000 documents?

11Explain the impact of an 'Upsert' on a high-write collection with multiple indexes.

12How does MongoDB handle Write Concern (w: 1 vs w: majority) and what are the latency trade-offs?

13What is a 'Covered Query' and how do you design one using Projection?

14How does the WiredTiger engine handle concurrency during a massive updateMany operation?

15What is the difference between replaceOne and updateOne with $set in terms of performance and BSON size?

16How do you update an element inside a deeply nested array using Array Filters (arrayFilters)?

17What are the operational risks of running a deleteMany({}) on a collection with millions of records?

18Is data truly removed from the disk immediately after a delete?

19You are scraping 1 million products per day using Puppeteer. If a product price changes, you need to update it, but if it's new, you must insert it. You also need to track the 'Last Seen' timestamp. How would you structure this CRUD operation to be most efficient?

MongoDB

Bulk Operations

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How to read records in MongoDB via Node.js?

MongoDB provides the following methods to read documents from a collection:

1
db.collection.find()
2
db.collection.findOne()

To select all documents in the collection, pass an empty document as the query filter parameter to the find method:

Equality condition:

The following example retrieves all documents from the inventory collection where status equals either 'A' or 'D':

A compound query can specify conditions for more than one field in the collection's documents. Implicitly, a logical AND conjunction connects the clauses of a compound query so that the query selects the documents in the collection that match all the conditions.

Using the $or operator, you can specify a compound query that joins each clause with a logical OR conjunction so that the query selects the documents in the collection that match at least one condition.

AND as well as OR Conditions