Questions
5 of 19
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?
MongoDBMongoDB
Basics
CRUD
Bulk Operations
Indexing
Data Modelling
Replication
Sharding
Transactions
Aggregation
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What is Projection Operators?

Projection operators in MongoDB are used to control which fields are returned in query results. They allow you to include or exclude specific fields, reshape documents, and optimize performance by reducing the amount of data transferred.

Basic Projection Operators: In the .find() method, the second argument is the projection object.
  1. 1

    1 means Include.

  2. 2

    0 means Exclude.

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Advanced Projection Operators:
  1. 1

    $: Projects the first element in an array that matches the query condition.

  2. 2

    $elemMatch: Projects the first element in an array that matches the specified $elemMatch condition.

  3. 3

    $meta: Projects the document's score assigned during the $text operation.

  4. 4

    $text: provides text query capabilities for self-managed (non-Atlas) deployments. For data hosted on MongoDB Atlas, MongoDB offers an improved full-text query solution, Atlas Search.

  5. 5

    $slice: Limits the number of elements projected from an array. Supports skip and limit slices.

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