💥 v8.0.0 - ChromaDB Backend Removal (BREAKING CHANGE)

⚠️ BREAKING CHANGE: The ChromaDB backend has been completely removed from the codebase.

🎯 TL;DR

• ChromaDB backend removed - 2,841 lines of code deleted
• Migration required for ChromaDB users - See guide below
• No action needed for SQLite-vec, Cloudflare, or Hybrid users
• Performance boost - Eliminated ~2GB PyTorch dependency
• Legacy branch available - Full code preserved for reference

❌ What's Removed

ChromaDB Backend Complete Removal

• Deleted: 2,841 lines of ChromaDB-related code
• Core files removed:
  • src/mcp_memory_service/storage/chroma.py (1,501 lines)
  • src/mcp_memory_service/storage/chroma_enhanced.py (176 lines)
  • tests/unit/test_chroma.py
  • tests/chromadb/test_chromadb_types.py
• Dependencies eliminated:
  • chromadb optional dependency group
  • ~2GB PyTorch + sentence-transformers burden

📦 Migration & Legacy Support

ChromaDB Legacy Branch

• Branch: chromadb-legacy
• Tag: chromadb-legacy-final
• Status: Frozen/Archived (no active maintenance)
• Purpose: Historical reference and migration support

Migration Resources

• Migration Guide: docs/guides/chromadb-migration.md
• Migration Script: scripts/migration/legacy/migrate_chroma_to_sqlite.py (in legacy branch)
• Tracking Issue: #148

✅ Supported Storage Backends (v8.0.0+)

📊 Impact & Rationale

Why Remove ChromaDB?

• Performance: ChromaDB 15ms vs SQLite-vec 5ms (3x slower)
• Dependencies: ~2GB PyTorch download eliminated
• Maintenance: 2,841 lines removed reduces complexity
• Better Alternatives: Hybrid backend provides superior performance with cloud sync

For Existing ChromaDB Users

• ✅ No immediate action required - Continue using v7.x releases
• ✅ Upgrade path available - Migration guide provided
• ✅ Legacy branch preserved - Full code available for reference
• ✅ Support timeline: v7.x remains available (no new features)

🚀 Upgrade Instructions

For ChromaDB Users (REQUIRED MIGRATION)

1. Backup your data:
```bash

Switch to legacy branch for migration tools

git checkout chromadb-legacy
python scripts/migration/migrate_chroma_to_sqlite.py --backup ~/chromadb_backup.json
```

2. Switch backend (RECOMMENDED: Hybrid):
```bash

Recommended: Hybrid backend (best of both worlds)

export MCP_MEMORY_STORAGE_BACKEND=hybrid

Configure Cloudflare credentials for cloud sync

export CLOUDFLARE_API_TOKEN="your-token"
export CLOUDFLARE_ACCOUNT_ID="your-account"
export CLOUDFLARE_D1_DATABASE_ID="your-d1-id"
export CLOUDFLARE_VECTORIZE_INDEX="mcp-memory-index"
```

Alternatives:
```bash

SQLite-vec (local-only)

export MCP_MEMORY_STORAGE_BACKEND=sqlite_vec

Cloudflare (cloud-only)

export MCP_MEMORY_STORAGE_BACKEND=cloudflare
```

3. Update to v8.0.0:
```bash
git checkout main
git pull origin main
python install.py --storage-backend hybrid
```

4. Validate migration:
```bash
python scripts/validation/validate_configuration_complete.py
```

For Non-ChromaDB Users (No Action Required)

✅ Seamless upgrade - No breaking changes for SQLite-vec, Cloudflare, or Hybrid users
✅ Reduced footprint - Enjoy lighter dependencies and simplified codebase
✅ Same features - All memory operations work identically

📚 Documentation

• Migration Guide: docs/guides/chromadb-migration.md
• Architecture Updates: docs/architecture.md
• Storage Backends Guide: docs/guides/STORAGE_BACKENDS.md

🔧 Technical Changes

Code Removed

• ChromaDB storage backend implementations
• ChromaDB-specific tests and fixtures
• ChromaDB configuration handling in factory
• ChromaDB deprecation warnings in server.py

Error Handling

• Using MCP_MEMORY_STORAGE_BACKEND=chroma now raises clear ValueError
• Error messages include links to migration guide and legacy branch
• Fallback logic removed - only valid backends accepted

Dependencies

• Removed chromadb>=0.5.0 from optional dependencies
• Updated full dependency group to exclude chromadb
• No impact on core dependencies

🔗 Resources

• Issue #148: ChromaDB Deprecation Plan
• Legacy Branch: chromadb-legacy
• Legacy Tag: chromadb-legacy-final
• Migration Guide: docs/guides/chromadb-migration.md

📝 Full Changelog

See CHANGELOG.md for complete details.

Questions? Open an issue or check the migration guide.