Vector Database Selection Guide

As a Lead AI Engineer, help me select the optimal vector database for our use case.

## Requirements
{{requirements}}

## Scale Expectations
- Initial vectors: {{initial_vector_count}}
- Growth rate: {{monthly_growth_rate}}
- Query patterns: {{query_patterns}}

Compare the following options: Pinecone, Weaviate, Milvus, Qdrant, and pgvector.

For each option, evaluate:
1. Scalability for our growth trajectory
2. Query latency at our expected scale
3. Cost implications (infrastructure + licensing)
4. Operational complexity
5. Integration effort with existing stack

Provide a final recommendation with justification.