What is the fine-grained topic of the following text: For the APB-1 Benchmark density 5, the fastest performance results are published by Oracle-Express and take 4.5 hours to generate a partial cube of about 30GB while the corresponding Dwarf cube is generated in 21 minutes and has a size of 4.3GB. Only return the topic.
Performance comparison of Oracle-Express and Dwarf cube in generating APB-1 Benchmark density 5.