A data warehouse is an information provider that collects necessary datafrom individual source databases to support the analytical processing of decision-support functions. In the past, research on data warehouses primarily focused onrelational data models. In this paper, the concept of object-oriented data warehousingis introduced, and three algorithms, including instance-insertion, instance-deletion andinstance-modification, are proposed to maintain the consistency between the datawarehouse and the source databases. Time complexity is also analyzed to show theirperformance.