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Simon Cooper

Principal Software Engineer I

Author's articles

How we built Elasticsearch simdvec to make vector search one of the fastest in the world

Vector Database Inside Elastic

April 23, 2026

How we built Elasticsearch simdvec to make vector search one of the fastest in the world

How we built Elasticsearch simdvec, the hand-tuned SIMD kernel library behind every vector search query in Elasticsearch.

By: Chris Hegarty, Lorenzo Dematte and Simon Cooper

Elasticsearch 9.3 adds bfloat16 vector support

Vector Database

February 16, 2026

Elasticsearch 9.3 adds bfloat16 vector support

Exploring the new Elasticsearch element_type: bfloat16, which can halve your vector data storage.

By: Simon Cooper

HNSW graph: How to improve Elasticsearch performance

September 29, 2025

HNSW graph: How to improve Elasticsearch performance

Learn how to use the HNSW graph M and ef_construction parameters to improve search performance.

By: Simon Cooper

Using Direct IO for vector searches

Vector Database

August 8, 2025

Using Direct IO for vector searches

Using rescoring for kNN vector searches improves search recall, but can increase latency. Learn how to reduce this impact by leveraging direct IO.

By: Simon Cooper

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