# Amazon S3 Vectors adds metadata pre‑filtering for faster filtered search

> The new feature evaluates metadata before similarity search, delivering up to five times more matching vectors at no extra cost.

Oossa · 2026-09-30 · https://oossa.com/en/amazon-s3-vectors-adds-metadata-pre-filtering-for-faster-filtered-search

Amazon S3 Vectors now runs a metadata pre‑filter step before the similarity lookup. This can return up to five times more of the vectors that meet a selective filter. A new $startsWith operator lets you filter on path‑like strings. Existing indexes can be switched to the mode with a single UpdateIndexMode call; new buckets use it by default. The change rolls out across all commercial AWS regions at no extra charge.

## The facts

- Up to 5× higher recall on filtered queries
- Feature announced on Sep 30 2026

## Why it matters

Developers building RAG or semantic‑search apps can get more relevant results without changing code or paying extra.

## Sources & references

1. [Amazon S3 Vectors introduces metadata pre-filtering for up to 5x higher recall on filtered search](https://aws.amazon.com/about-aws/whats-new/2026/09/s3-vectors-introduces-metadata-pre-filtering/) – AWS, 2026-09-30

Last updated: 2026-09-30