Overview

MongoDB database storing all comments, mentions, reactions, and threaded discussions with flexible schema for rich-text content.

Collections

Technical Details

Specifications:

• Version: MongoDB 7.x
• Storage: 200 GB
• Replication: 3-node replica set
• Sharding: Sharded by workspace_id
• Encryption: Encrypted at rest

Performance:

• Query Latency: P95 < 100ms
• Write Throughput: 2,000 writes/second
• Connections: Max 500
• Uptime SLA: 99.95%

Schema Design

Comments Document

{
  "_id": "comment_123",
  "workspace_id": "ws_456",
  "task_id": "task_789",
  "author_id": "user_101",
  "content": {
    "text": "Great work on this feature!",
    "markdown": "Great work on **this feature**!",
    "mentions": ["user_102", "user_103"]
  },
  "attachments": [
    {
      "id": "att_1",
      "filename": "screenshot.png",
      "url": "s3://bucket/workspace/comment/att_1",
      "size": 102400,
      "mime_type": "image/png"
    }
  ],
  "reactions": {
    "👍": ["user_102", "user_103"],
    "🎉": ["user_104"]
  },
  "thread_id": null,
  "created_at": "2024-01-15T10:30:00Z",
  "updated_at": "2024-01-15T10:30:00Z",
  "edited": false
}

Indexing

• workspace_id + task_id + created_at - Fetch comments for task
• author_id + created_at - User’s comment history
• mentions - Find comments mentioning user
• content.text - Full-text search

Access Patterns

• Comment Service: Full read/write access
• Task Service: Read comment counts
• Notification Service: Read mentions for notifications
• Search: Full-text search across comments

Disaster Recovery

• RPO: 1 hour
• RTO: 2 hours
• Backup Retention: 30 days
• Point-in-Time Recovery: 24 hours