Vespa Product Updates, December 2019: Improved ONNX support, New rank feature attributeMatch().maxWeight, Free lists for attribute multivalue mapping, faster updates for out-of-sync documents, Zookeeper 3.5.6

In December 2019, Vespa announced several product updates aimed at enhancing its open-source big data processing and serving engine, which is widely used in Yahoo products and the Verizon Media Ad Platform. Key enhancements include improved support for ONNX models, specifically adding operations like General Matrix to Matrix Multiplication and better PyTorch integration, alongside the introduction of a new ranking feature called attributeMatch().maxWeight. Additionally, Vespa implemented free lists for multivalue attribute mapping to boost performance by reducing CPU usage and memory, particularly beneficial for applications with high update rates. Other improvements include faster updates for out-of-sync documents using bucket checksums and the adoption of Apache ZooKeeper 3.5.6 with encrypted communication capabilities. These updates reflect Vespa's ongoing development and its commitment to integrating community feedback and contributions.