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What indexing algorithms are supported by AWS S3 Vector (e.g., FAISS, HNSW)?

AWS S3 Vector abstracts the underlying indexing algorithms from users, automatically handling the selection and optimization of indexing methods without exposing specific algorithm choices like FAISS or HNSW. The service manages indexing infrastructure internally, automatically optimizing vector storage and search structures as you add, update, and delete vectors over time. This approach simplifies operations by eliminating the need to understand, configure, or tune complex indexing algorithms, but it also means developers cannot directly specify or customize the indexing approach for their specific use cases.

The abstracted indexing system focuses on providing consistent sub-second query performance for typical workloads while scaling automatically to handle billions of vectors per index. AWS likely employs multiple indexing strategies optimized for different scenarios, such as approximate nearest neighbor (ANN) algorithms for large-scale similarity search and exact search methods for smaller datasets or specific accuracy requirements. The service automatically selects and adjusts indexing parameters based on your data characteristics, query patterns, and performance requirements without requiring manual intervention or algorithm expertise from developers.

While this abstraction provides operational simplicity, it limits advanced users who might want to fine-tune indexing parameters for specific performance characteristics or accuracy trade-offs. Traditional vector databases often allow developers to choose between algorithms like HNSW for fast approximate search, IVF for memory-efficient indexing, or exact search methods when precision is critical. S3 Vector’s managed approach prioritizes ease of use and consistent performance over algorithmic flexibility. The service likely implements industry-standard ANN algorithms under the hood, but the specific implementations, parameters, and optimization strategies remain internal to AWS. This design choice aligns with AWS’s serverless philosophy of abstracting infrastructure complexity while providing predictable performance and automatic scaling capabilities.

Will Amazon S3 vectors kill vector databases or save them?

S3 vectors looks great particularly in terms of price and integration into the AWS ecosystem. So naturally, there are a lot of hot takes. I’ve seen folks on social media and in engineering circles say this could be the end of purpose-built vector databases—Milvus, Pinecone, Qdrant, and others included. Bold claim, right?

As a group of people who’s spent way too many late nights thinking about vector search, we have to admit that: S3 Vectors does bring something interesting to the table, especially around cost and integration within the AWS ecosystem. But instead of “killing” vector databases, I see it fitting into the ecosystem as a complementary piece. In fact, its real future probably lies in working with professional vector databases, not replacing them.

Check out James’ post to learn why we think that—looking at it from three angles: the tech itself, what it can and can’t do, and what it means for the market. We’ll also share S3 vectors’ strenghs and weakness and in what situations you should choose an alternative such as Milvus and Zilliz Cloud.

Will Amazon S3 Vectors Kill Vector Databases—or Save Them?

Or if you’d like to compare Amazon S3 vectors with other specialized vector databases, visit our comparison page for more details: Vector Database Comparison

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