Pinecone is a fast, scalable, and easy-to-use closed-source vector database provider that has been considered for its ability to perform blazing-fast vector search, but it may not be the best choice for large-scale LLM applications due to several hidden complexities and limitations. Its simplistic design belies issues with integrating with existing data storage solutions, restrictive metadata storage capacity, and data synchronization problems, which can turn it into a scalability hell. In contrast, pgvector offers better performance, scalability, and flexibility, although it also has its own set of challenges, such as unifying fragmented data sources. Overall, Pinecone may be suitable for proof-of-concept projects but requires significant effort to maintain a scalable and performant search infrastructure, making it less ideal for large-scale LLM applications.