Blob Storage
Using services like Amazon S3 to store large, unstructured files like videos and PDFs
Overview
Blob (Binary Large Object) storage is designed for storing unstructured data like images, videos, documents, and backups. Services like Amazon S3, Azure Blob Storage, and Google Cloud Storage are optimized for this use case.
Traditional databases are poor for large files - blob storage provides scalable, durable, and cost-effective solutions.
Key Concepts
Object Storage
Files stored as objects with metadata. Accessed via unique keys/URLs. No hierarchical file system.
Bucket/Container
Top-level organizational unit for storing objects. Like a folder but flatter structure.
Durability
Data replicated across multiple locations. S3 offers 99.999999999% (11 nines) durability.
CDN Integration
Blob storage often integrates with CDNs for fast global delivery of static assets.
How It Works
Upload Flow:
- User uploads file to your app
- App generates unique filename
- App uploads to blob storage (S3, Azure, GCS)
- Storage returns public URL
- App stores URL in database
- Serves file via URL (optionally through CDN)
Example S3 URL: https://mybucket.s3.amazonaws.com/images/photo123.jpg
Database only stores the URL, not the file itself.
Use Cases
Image and video storage for social media
Document management systems
Backup and disaster recovery
Log file archival
Static website hosting
Media streaming
Data lakes for analytics
Best Practices
Use CDN in front of blob storage for frequently accessed files
Implement proper access controls (private vs public)
Use signed URLs for temporary access
Enable versioning for critical data
Set up lifecycle policies (move old data to cheaper storage tiers)
Compress files before upload when possible
Use appropriate storage classes (hot, cool, archive)
Implement retry logic for uploads
Store metadata in database, files in blob storage
Interview Tips
What Interviewers Look For
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Explain why databases are bad for large files: blob fields break normalization, slow queries, expensive storage
- •
Discuss major providers: AWS S3, Azure Blob Storage, Google Cloud Storage
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Mention durability: how blob storage replicates across regions
- •
Talk about cost optimization: storage tiers (hot/cool/archive)
- •
Explain CDN integration for performance
- •
Discuss security: public vs private buckets, signed URLs, IAM policies
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Mention use cases: images, videos, backups, static sites