EP170: All-in-One Technical Interview Prep Kit

ByteByteGo Jul 5

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This week’s system design refresher:

• All-in-One ByteByteGo Technical Interview Prep Kit

• Best ways to test system functionality

• How CQRS Works

• How MongoDB Works

• Who’s Hiring Now

• SPONSOR US

ByteByteGo Technical Interview Prep Kit

Launching the All-in-one interview prep. We’re making all the books available on the ByteByteGo website.

What's included:

• System Design Interview

• Coding Interview Patterns

• Object-Oriented Design Interview

• How to Write a Good Resume

• Behavioral Interview (coming soon)

• Machine Learning System Design Interview

• Generative AI System Design Interview

• Mobile System Design Interview

• And more to come

Launch sale: 50% off

Best ways to test system functionality

Testing system functionality is a crucial step in software development and engineering processes.

It ensures that a system or software application performs as expected, meets user requirements, and operates reliably.

Here we delve into the best ways:

1. Unit Testing: Ensures individual code components work correctly in isolation.

2. Integration Testing: Verifies that different system parts function seamlessly together.

3. System Testing: Assesses the entire system's compliance with user requirements and performance.

4. Load Testing: Tests a system's ability to handle high workloads and identifies performance issues.

5. Error Testing: Evaluates how the software handles invalid inputs and error conditions.

6. Test Automation: Automates test case execution for efficiency, repeatability, and error reduction.

Over to you: How do you approach testing system functionality in your software development or engineering projects?

Over to you: what's your company's release process look like?

How CQRS Works?

CQRS (Command Query Responsibility Segregation) separates write (Command) and read (Query) operations for better scalability and maintainability.

Here’s how it works:

1 - The client sends a command to update the system state. A Command Handler validates and executes logic using the Domain Model.

2 - Changes are saved in the Write Database and can also be saved to an Event Store. Events are emitted to update the Read Model asynchronously.

3 - The projections are stored in the Read Database. This database is eventually consistent with the Write Database.

4 - On the query side, the client sends a query to retrieve data.

5 - A Query Handler fetches data from the Read Database, which contains precomputed projections.

6 - Results are returned to the client without hitting the write model or the write database.

Over to you: What else will you add to understand CQRS?

How MongoDB Works?

MongoDB is a popular NoSQL database designed for flexibility, scalability, and high performance. It stores data in a JSON-like format (BSON) and supports horizontal scaling through sharding and replication.

Here’s how it works:

1. Client application connects via a MongoDB Driver to perform read/write operations.

2. The Query Router (mongos) acts as a mediator, directing queries to the appropriate shard based on the data’s shard key.

3. Config servers store metadata and routing information. This helps query routers locate data across shards.

4. The data is distributed across multiple shards to support horizontal scaling.

5. Each shard is a replica set that consists of one primary node for handling writes and multiple secondary nodes for high availability and read scaling.

6. If a primary fails, a secondary is automatically elected to replace it and maintain availability.

Over to you: What else will you add to understand MongoDB’s working better?

Hiring Now

We collaborate with Jobright.ai (an AI job search copilot trusted by 500K+ tech professionals) to curate this job list.

This Week’s High-Impact Roles at Fast-Growing AI Startups

• Principal Software Engineer, Linux PCIe Device Drivers at SIMa.ai (San Jose, CA)

  • Yearly: 220000 - 296400

  • SiMa.ai is a developer of machine learning technology to deliver a software-centric platform.

• Senior Software Engineer (C++ Focus) at Inworld AI (Mountain View, CA)

  • Yearly: 200000 - 250000

  • Inworld AI is an AI framework powering massive consumer applications.

• Senior / Staff Software Engineer, Motion Planning at Waabi (San Francisco County, CA)

  • Yearly: 158000 - 269000

  • Waabi is an artificial intelligence company that develops autonomous driving technology for the transportation sector.

High Salary SWE Roles this week

• Vice President, Engineering - Data Science and Data Engineering Products at NVIDIA (Santa Clara, CA)

  • Yearly: 480000 - 690000

• Senior Software Engineer, Core Infrastructure at Anthropic (Seattle, WA)

  • Yearly: 320000 - 485000

• Distinguished Engineer at Okta (New York)

  • Yearly: 294000 - 440000

Today’s latest ML positions - hiring now!

• Director of Machine Learning Engineering at Workday (Boulder, CO)

  • Yearly: 307200 - 460800

• Sr Director, Machine Learning Engineering at Paypal (San Jose, CA)

  • Yearly: 232000 - 398750

• Staff Machine Learning Engineer - Expansion ML at Square (US)

  • Yearly: 228700 - 343100

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