Support for distributed transactions across heterogeneous storage technologies is either nonexistent or suffers from poor operational and performance characteristics. In contrast, OLEP is increasingly used to provide good performance and strong consistency guarantees in such settings. In data systems it is very common for logs to be used as internal implementation details. The OLEP approach is different: it uses event logs, rather than transactions, as the primary application programming model for data management. Traditional databases are still used, but their writes come from a log rather than directly from the application. The use of OLEP is not simply pragmatism on the part of developers, but rather it offers a number of advantages. Consequently, OLEP is expected to be increasingly used to provide strong consistency in large-scale systems that use heterogeneous storage technologies.