Denodo is a data virtualization tool that aims to make it easier to expose and secure transformed, consumer-friendly data (from multiple underlying data sources and through a variety of interfaces) from one platform. Data transformations within Denodo can be defined by creating virtual databases and views using a SQL-like language called VQL which are executed when a user queries the virtual database. Underneath, Denodo can delegate queries on the virtual databases against one or multiple underlying databases.
Although Denodo makes it easy to start exposing consumer-friendly data, performance degrades as layers of views and virtual databases are built on top of each other and queries with multiple joins start hitting multiple underlying databases. These problems are solvable, but they require fairly deep knowledge of the product's behavior and performance tuning options. Because of these drawbacks and given its limited support for unit testing, we recommend that you do not use Denodo as a primary data transformation tool and use tools like Spark or SQL (with dbt) for your data transformations instead.