tailieunhanh - Building the Data Warehouse Third Edition phần 5

1-năm chân trời trong tràn và dữ liệu trên đĩa, đa số trong tràn, rất cẩn thận xem xét các granularity Có thể Một số dữ liệu trong tràn, MOST dữ liệu trên đĩa, Một số Xem xét dữ liệu trên granularity đĩa, Hầu như bất kỳ thiết kế cơ sở dữ liệu cơ sở dữ liệu thiết kế và Cổ 100,000 , tất cả các dữ liệu trên đĩa | Uttama Reddy 50 CHAPTER 4 space estimates row estimates How much DASD is needed How much lead time for ordering can be expected Are dual levels of granularity needed Figure Using the output of the space estimates. 1-year horizon 5-year horizon 100 000 000 data in overflow and on disk majority in overflow very careful consideration of granularity 10 000 000 possibly some data in overflow most data on disk some consideration of granularity 1 000 000 data on disk almost any database design 100 000 any database design all data on disk 1 000 000 000 data in overflow and on disk majority in overflow very careful consideration of granularity 100 000 000 possibly some data in overflow most data on disk some consideration of granularity 10 000 000 data on disk almost any database design 1 000 000 any database design all data on disk Figure Compare the total number of rows in the warehouse environment to the charts. fewer than 100 000 practically any design and implementation will work and no data will have to go to overflow. If there will be 1 million total rows or fewer design must be done carefully and it is unlikely that any data will have to go into overflow. If the total number of row will exceed 10 million design must be Uttama Reddy Granularity in the Data Warehouse 151 done carefully and it is likely that at least some data will go to overflow. And if the total number of rows in the data warehouse environment is to exceed 100 million rows surely a large amount of data will go to overflow storage and a very careful design and implementation of the data warehouse is required. On the five-year horizon the totals shift by about an order of magnitude. The theory is that after five years these factors will be in place There will be more expertise available in managing the data warehouse volumes of data. Hardware costs will have dropped to some extent. More powerful software tools will be available. The end user will be more sophisticated. All of these factors .