Lesson Learned #047: RAG Dual Database Cleanup Needed

ID: LL-047 Impact: Identified through automated analysis

Date: December 15, 2025 Severity: MEDIUM Category: Technical Debt, RAG, Infrastructure Status: IDENTIFIED (cleanup pending)

The Problem

We have two RAG vector databases in the codebase:

Database Files Using Status
ChromaDB 2 files Legacy
LanceDB 3 files Newer

This creates:

  • Confusion about which to use
  • Double dependencies
  • Inconsistent behavior
  • CI failures when one is missing

How We Got Here

  1. Started with ChromaDB (legacy)
  2. Someone added LanceDB (newer, simpler)
  3. Neither was fully migrated
  4. Both are now “required”

Today’s Fix (Bandaid)

Added both to requirements-minimal.txt:

chromadb==0.6.3
lancedb>=0.4.0

This fixes CI but doesn’t solve the underlying mess.

Why LanceDB:

  • Simpler API
  • No server needed
  • Better for embeddings
  • More modern

Steps:

  1. Migrate ChromaDB code to LanceDB
  2. Remove ChromaDB from requirements
  3. Test RAG functionality
  4. Delete old ChromaDB files

Option B: Consolidate to ChromaDB

Why ChromaDB:

  • More established
  • Better documentation
  • Larger community

Steps:

  1. Migrate LanceDB code to ChromaDB
  2. Remove LanceDB from requirements
  3. Test RAG functionality
  4. Delete old LanceDB files

Files to Review

ChromaDB users:

  • rag_store/vector_store.py
  • src/rag/unified_rag.py

LanceDB users:

  • src/rag/lessons_indexer.py
  • src/rag/lightweight_rag.py
  • src/rag/lessons_search.py

Priority

  • P2 - Not urgent but creates technical debt
  • Cleanup in next sprint (Week 4)

Tags

rag, technical_debt, chromadb, lancedb, cleanup