Query Time Constrained Approximate Nearest Neighbor Search

Vespa offers a robust solution for integrating approximate nearest neighbor (ANN) search with query-time filters, crucial for real-world search and recommendation systems. It employs two main strategies, pre-filtering and post-filtering, to balance performance and accuracy, allowing developers to choose based on application needs. Pre-filtering evaluates constraints before searching the HNSW graph, potentially leading to higher resource use but better results exposure, while post-filtering applies constraints after retrieving neighbors, which is less resource-intensive but might yield fewer results. Vespa also provides parameters to dynamically adjust filtering strategies based on query estimates, enhancing flexibility and resource efficiency. These features enable Vespa to support complex use cases, such as AI-powered vector searches in e-commerce and multimedia applications, by optimizing query execution plans and balancing computational costs with accuracy.