AWS Upgrades S3 Vectors with Metadata Pre-Filtering for Higher Recall
Amazon Web Services (AWS) has announced that its S3 Vectors service now supports metadata pre-filtering, which allows for higher recall on filtered searches. This feature evaluates a user's metadata filter before performing a similarity search, delivering more relevant results.
The new functionality applies to attributes such as tenant ID, category, status, and time, and also adds prefix matching with $startsWith for paths, URLs, and hierarchical keys. Each vector in an S3 Vectors index can carry up to 2 KB of filterable metadata, and a single query supports up to 100 filter constraints.
According to AWS, the common use cases for pre-filtering include legal and professional services, financial services, media and entertainment, and agentic applications. In these scenarios, pre-filtering improves recall by narrowing down the search space to vectors matching specific conditions.