Decision Framework: Which One Should You Pick?

You have the features, the costs, and the operational complexity. Now, it's time to make a choice. In this final lesson of Module 19, we present the Architect's Decision Tree.

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1. The 3-Step Decision Tree

Step 1: Volume

• < 100k Vectors: Use Chroma. It's simple, free, and perfectly capable at this size.
• > 1M Vectors: Move to Pinecone (Serverless) or OpenSearch.

Step 2: Complexity

• Do you need Hybrid Search (Keywords AND Vectors)?
  • Yes: Use OpenSearch.
  • No: Stick with Pinecone or Chroma.
• Do you need to run on a local machine/edge device?
  • Yes: Use Chroma.

Step 3: Infrastructure

• Does your team have DevOps/DBA capacity?
  • Yes: Consider OpenSearch for maximum control.
  • No: Use Pinecone. It's the most "Feature-Rich" while remaining "Low-Touch."

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2. Visual Decision Matrix

graph TD
    A[Start: I need a Vector DB] --> B{Billions of Vectors?}
    B -->|Yes| C[Pinecone or OpenSearch]
    B -->|No| D{Local App?}
    D -->|Yes| E[Chroma]
    D -->|No| F{Need Hybrid Search?}
    F -->|Yes| G[OpenSearch]
    F -->|No| H[Pinecone]

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3. The "Standard Stack" Recommendation (2024-2026)

If you are a solo developer or a small startup building a RAG app today:

1. Embeddings: OpenAI text-embedding-3-small
2. Database: Pinecone Standard Tier
3. Reasoning: It gives you the best reliability and scaling headroom for the lowest amount of engineering effort.

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4. Summary and Key Takeaways

1. Don't Over-Engineer: Start with Chroma, but write your code so you can swap to Pinecone later (Module 19.4).
2. Hybrid Search is a Filter: If your users expect "Exact keyword matching" (e.g., searching for parts numbers), OpenSearch is mandatory.
3. Cost is a Lagging Indicator: Don't worry about the $200/month bill difference until you have enough users to pay for it.
4. Platform Lock-in: If you use a managed provider, ensure you have a "Snapshot" strategy (Module 15.5) so you can move your data if they change their pricing.

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Exercise: The Architect's Recommendation

1. Scenario: A law firm wants to search 50,000 sensitive legal briefs. They refuse to use "Public Cloud" storage. They need to find exact citations (keywords) AND semantic concepts.
2. The Question: Based on this Module, which database would you recommend? How would you set it up?

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Congratulations on completing Module 19! You are now prepared to choose the foundation for your AI future.