Methods, systems and computer program products for detecting anomalies for a database system are provided. A method may include extracting workload features from a query optimizer based on a query workload and generating feature models for the extracted workload features. The method may also include extracting instance features from the query optimizer based on a query instance. Instance feature values may be obtained. The method may further include applying a query instance to the workload feature models to produce a prediction value for each workload feature. Anomalies may be reported based on a comparison of each instance feature value with a corresponding prediction value. A system for detecting anomalies for a database system may include a query optimizer, a feature modeler and an anomaly detector.