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DiskANN

Concept

DiskANN is a graph-based approximate nearest neighbor search algorithm from Microsoft Research that keeps a compressed navigation layer in RAM and the full-precision graph on SSD. It is used in services such as Azure Cosmos DB and SQL Server vector search.

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Title graphic: DiskANN (Concept)
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Key points about DiskANN

Episodes about DiskANN

HNSW vs DiskANN for Vector Search in Azure AI Search

2026-06-08 · Video on YouTube

The explosion of AI-powered applications has created a new challenge: how do you efficiently search through billions of vector embeddings without exploding infrastructure costs? In this episode, we explore the “billion-vector problem” and compare two leading…

Articles about DiskANN (2)

Frequently asked questions

What is the difference between HNSW and DiskANN?

HNSW works in memory with low latency and high recall but needs lots of RAM, while DiskANN uses SSDs to scale to massive datasets with less RAM. · From the episode: HNSW vs DiskANN for Vector Search in Azure AI…

Who developed the DiskANN algorithm?

DiskANN was originally developed by Microsoft Research. It is available in Azure AI Search as an alternative to HNSW for very large vector datasets. · From the episode: HNSW vs DiskANN for Vector Search in Azure AI…

Why does DiskANN reduce cost?

DiskANN relies on SSDs rather than RAM, so memory costs fall for large datasets. This addresses the cost problem of searching through very large numbers of vector embeddings. · From the episode: HNSW vs DiskANN for Vector Search in Azure AI…

Glossary

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Sources

Maintained by Mirko Peters (Microsoft MVP) · Last updated: