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Visa·Software Engineer·Onsite - System Design / Architecture·Senior

SeniorPrefer not to say
Jul 2026

Summary

System design round at Visa for a software engineering role. Just one question but it had enough surface area to go in a lot of directions, which I found both freeing and kind of paralyzing.

Questions Asked (1)

Q1

Design a system that stores multiple images inside a single file, with support for efficient storage, retrieval, and metadata.

System DesignTechnical Trade-offsData Modeling
Author's notes

I started with the obvious stuff, a container format with a header index, offsets per image, maybe a footer checksum.

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AI HintsAI Generated

Suggested Approach

Start by clarifying requirements such as file size, image types, access patterns, and metadata needs. Then propose a container format with a header, metadata index, and data blocks, and discuss trade-offs between simplicity and performance. Finally, outline how to implement efficient storage (e.g., compression, deduplication) and retrieval (e.g., indexing, random access).

Pro tip: Mention real-world formats like TIFF, PDF, or ZIP to show practical knowledge, and emphasize how your design handles Visa-scale requirements like high throughput and security.

1. Clarify Requirements

Ask about expected file size, number of images, image formats, metadata fields, access patterns (read/write ratio), and performance constraints.

2. Design File Format

Propose a container structure: a header with magic number and version, a metadata section (e.g., JSON or binary index), and a data section with image blobs. Consider fixed vs variable block sizes.

3. Address Storage Efficiency

Discuss compression (e.g., zlib, JPEG), deduplication (e.g., hashing), and alignment to optimize space and I/O.

4. Enable Efficient Retrieval

Design an index (e.g., offset table) for random access, and consider caching or memory-mapping for frequent reads.

5. Handle Metadata and Extensibility

Define a schema for metadata (e.g., image dimensions, timestamps, tags) and allow for future extensions via versioning or optional fields.

Key Points to Mention

  • Trade-offs between monolithic file and separate files (e.g., portability vs. concurrency)
  • Indexing strategies for fast lookup (e.g., B-tree, hash map, offset table)
  • Compression and deduplication techniques to reduce storage footprint
  • Concurrency control and atomicity for writes (e.g., locking, journaling)
  • Security considerations like encryption and access control
  • Real-world examples: TIFF, PDF, ZIP, and their pros/cons

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.