--- title: Amazon S3 Vectors introduces metadata pre-filtering for... description: Amazon S3 Vectors now supports metadata pre-filtering, evaluating filters before similarity search to return up to 5x more matching vectors when filters are... canonical: https://daily.dev/posts/amazon-s3-vectors-introduces-metadata-pre-filtering-for-up-to-5x-higher-recall-on-filtered-search-vtdkfvhmr twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Amazon S3 Vectors introduces metadata pre-filtering for up to 5x higher recall on filtered search | daily.dev og:description: Amazon S3 Vectors now supports metadata pre-filtering, evaluating filters before similarity search to return up to 5x more matching vectors when filters are... og:url: https://daily.dev/posts/amazon-s3-vectors-introduces-metadata-pre-filtering-for-up-to-5x-higher-recall-on-filtered-search-vtdkfvhmr og:image: https://api.daily.dev/og/posts/vTDKfvHMr.png og:image:alt: Amazon S3 Vectors introduces metadata pre-filtering for up to 5x higher recall on filtered search og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # Amazon S3 Vectors introduces metadata pre-filtering for up to 5x higher recall on filtered search **[AWS](https://daily.dev/sources/aws)** · 2 min read · 0 upvotes · 0 comments ## Summary Amazon S3 Vectors now supports metadata pre-filtering, evaluating filters before similarity search to return up to 5x more matching vectors when filters are selective. A new $startsWith prefix match operator is added for filtering values like paths and URLs. New vector buckets use pre-filtering by default; existing indexes can adopt it via the UpdateIndexMode API, with a per-query parameter available to compare results before switching. The feature is free in all commercial AWS Regions where S3 Vectors is available, plus AWS China Regions, with deployment completing in the coming days. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Questions this post answers ### How do I enable metadata pre-filtering on an existing Amazon S3 Vectors index? Use the UpdateIndexMode API to update an existing index in place to enable metadata pre-filtering. New vector buckets already use pre-filtering by default, requiring no changes to how vectors are written with PutVectors or queried with QueryVectors. A per-query parameter on QueryVectors also lets you compare pre-filtering results against current filtering on the same index before committing to the update. _Teams tuning RAG retrieval quality can track vector database feature updates like this on daily.dev._ ### What does the new $startsWith operator do in Amazon S3 Vectors metadata filtering? The $startsWith operator performs prefix matching on metadata values such as file paths and URLs when filtering vectors in Amazon S3 Vectors. It was introduced alongside metadata pre-filtering, which evaluates filters before similarity search to return up to 5x more matching vectors when a filter is selective, improving results for RAG, agentic, and semantic-search applications. _Developers filtering vector search by path or URL patterns can follow storage API changes like this via daily.dev._ ### Does Amazon S3 Vectors metadata pre-filtering cost extra? No, metadata pre-filtering is available at no additional cost in all commercial AWS Regions where Amazon S3 Vectors is available, as well as in the AWS China Regions. The rollout was being deployed gradually with completion expected within days of the announcement. _Anyone budgeting a vector search stack can keep an eye on AWS pricing and feature changes through daily.dev._ ## Similar posts on daily.dev - [Amazon S3 Vectors now supports metadata pre-filtering for higher recall on filtered searches](https://daily.dev/posts/amazon-s3-vectors-now-supports-metadata-pre-filtering-for-higher-recall-on-filtered-searches-ddolirhc3) · AWS · 0 upvotes · 0 comments - [Amazon S3 Vectors now generally available with increased scale and performance](https://daily.dev/posts/amazon-s3-vectors-now-generally-available-with-increased-scale-and-performance-0gpqkus8w) · AWS · 0 upvotes · 0 comments - [Amazon S3 Vectors Reaches GA, Introducing "Storage-First" Architecture for RAG](https://daily.dev/posts/amazon-s3-vectors-reaches-ga-introducing-storage-first-architecture-for-rag-ebcqk2lpm) · InfoQ · 0 upvotes · 0 comments - [S3 Vectors with OpenSearch: Cost-Efficient Hybrid Vector Search](https://daily.dev/posts/s3-vectors-with-opensearch-cost-efficient-hybrid-vector-search-xabkmmtbp) · BigData Boutique blog · 1 upvotes · 0 comments --- Tags: [#aws](https://daily.dev/tags/aws), [#rag](https://daily.dev/tags/rag), [#vector-search](https://daily.dev/tags/vector-search) [View this post on daily.dev](https://daily.dev/posts/amazon-s3-vectors-introduces-metadata-pre-filtering-for-up-to-5x-higher-recall-on-filtered-search-vtdkfvhmr) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"Amazon S3 Vectors introduces metadata pre-filtering for up to 5x higher recall on filtered search","url":"https://daily.dev/posts/amazon-s3-vectors-introduces-metadata-pre-filtering-for-up-to-5x-higher-recall-on-filtered-search-vtdkfvhmr","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/amazon-s3-vectors-introduces-metadata-pre-filtering-for-up-to-5x-higher-recall-on-filtered-search-vtdkfvhmr"},"datePublished":"2026-09-30T21:05:07.510Z","dateModified":"2026-09-30T21:05:29.930Z","description":"Amazon S3 Vectors now supports metadata pre-filtering, evaluating filters before similarity search to return up to 5x more matching vectors when filters are...","image":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/2587ee7271b19b73b7c9d67f739e4290?_a=AQAEuop","thumbnailUrl":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/2587ee7271b19b73b7c9d67f739e4290?_a=AQAEuop","isAccessibleForFree":true,"articleSection":"AWS","inLanguage":"en","publisher":{"@type":"Organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180}},"author":{"@type":"Organization","name":"AWS","logo":"https://media.daily.dev/image/upload/t_logo,f_auto/v1/logos/aws","url":"https://daily.dev/sources/aws"},"commentCount":0,"discussionUrl":"https://daily.dev/posts/amazon-s3-vectors-introduces-metadata-pre-filtering-for-up-to-5x-higher-recall-on-filtered-search-vtdkfvhmr","interactionStatistic":[{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":0},{"@type":"InteractionCounter","interactionType":{"@type":"CommentAction"},"userInteractionCount":0}],"keywords":"aws,rag,vector-search","timeRequired":"PT2M"} {"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https://daily.dev"},{"@type":"ListItem","position":2,"name":"AWS","item":"https://daily.dev/sources/aws"},{"@type":"ListItem","position":3,"name":"Amazon S3 Vectors introduces metadata pre-filtering for up to 5x higher recall on filtered search"}]} {"@context":"https://schema.org","@type":"FAQPage","@id":"https://daily.dev/posts/amazon-s3-vectors-introduces-metadata-pre-filtering-for-up-to-5x-higher-recall-on-filtered-search-vtdkfvhmr#faq","mainEntity":[{"@type":"Question","name":"How do I enable metadata pre-filtering on an existing Amazon S3 Vectors index?","acceptedAnswer":{"@type":"Answer","text":"Use the UpdateIndexMode API to update an existing index in place to enable metadata pre-filtering. 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