Abstract: In some aspects, the disclosure is directed to methods and systems for access path selection optimization for relational database queries. Machine learning systems, such as neural networks, may be used to determine costs for each path. A neural network may be trained based on cost determinations from scans and indexes of the tree for an initial set of queries, and then may be used to predict costs for additional queries such that a path may be selected. The training data may be periodically refreshed or updated, or may be refreshed or updated responsive to changes in hardware or computing environment.