Design 64-bit distributed IDs and a parking lot

Q: Design 64-bit distributed IDs and a parking lot

The question evaluates distributed-systems and scalability competencies for globally unique 64-bit ID generation (including sharding, time-ordering, fault tolerance and clock issues) as well as object-oriented design, concurrency control, API design, and data modeling for a parking lot backend.

Q: How do I approach System Design interview questions?

System Design questions require understanding of core concepts and practice. PracHub provides solutions with explanations to help you master system design interviews.

Q: What difficulty level is this interview question?

This is a easy difficulty System Design question, commonly asked during Technical Screen rounds at Flipster.

Q: What role is this question designed for?

This question is commonly asked for Software Engineer candidates at Flipster during technical interviews.

Question

You have two system-design prompts.

1) 64-bit database ID generator

Design a service/library that generates globally unique 64-bit integer IDs for database records in a distributed system.

Requirements

IDs must be unique across all shards/regions .
Very high write rate (assume 100K–1M IDs/sec globally).
Prefer IDs that are roughly time-ordered to reduce index fragmentation.
Support sharding and growth in number of nodes.
Discuss how to avoid conflicts and what happens on failures (node restart, clock issues, network partitions).

Deliverables

Bit layout proposal (what each bit range means).
How nodes obtain any needed configuration (e.g., worker IDs).
How the system behaves under clock skew/rollback.
Operational considerations (monitoring, rotation, migrations).

2) Parking lot system (object-oriented + backend)

Design a parking lot management system.

Requirements (assume typical)

Multiple levels; each level has multiple spots of different types (compact/large/EV/handicapped).
Vehicles arrive/leave; system issues a ticket and calculates fees.
Track spot availability and prevent double-allocation under concurrency.
Provide APIs for: entering, exiting, querying availability, and (optionally) reserving a spot.

Deliverables

Core classes/entities and relationships.
Key APIs and data storage approach.
Concurrency/consistency approach for assigning/freeing spots.

Design 64-bit distributed IDs and a parking lot

Quick Overview

1) 64-bit database ID generator

Requirements

Deliverables

2) Parking lot system (object-oriented + backend)

Requirements (assume typical)

Deliverables

Solution

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