A plurality of operations are executed on tables of a database with at least a portion of the operations being executed in parallel. A constraint check is performed for each operation subsequent to its execution to determine whether data stored in the database affected by the operation is valid, during this constraint checking additional operations and/or constraint checks on the same table are allowed to run in parallel. Based on this constraint checking, operations for which the constraint check determines that the data is not valid are invalidated. Related apparatus, systems, techniques and articles are also described.