tailieunhanh - Managing time in relational databases- P17

Tham khảo tài liệu 'managing time in relational databases- p17', công nghệ thông tin, cơ sở dữ liệu phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 306 Chapter 13 RE-PRESENTING INTERNALIZED PIPELINE DATASETS Pending Updates exist in what we called in the previous chapter either the assertion-time near future or the assertiontime far future. Those in the near future have an assertion begin date close enough to Now that the business is willing to let the passage of time make them current. Near future deferred assertions would typically have a begin date that will become current in the next few seconds hours days or weeks. In a conventional database pending updates are transactions accumulated in an external batch transaction file or perhaps in a batch transaction table within the database. Far future deferred assertions are the internalization of data located in what are often called staging areas. They are collections of data that are usually more complicated than usual to update. By placing them in far future assertion time we guarantee that they will not inadvertently become current assertions simply because of the passage of time. They can become current assertions only when presumably after a review-and-approve process the business releases them into near-future assertion time. Pending Projections Future Claims About the Future The Pending Projections dataset consists of all those rows in an asserted version table which lie in both the assertion time future and in the effective time future. Its subject matter is things as they may turn out to be. Its rows are claims about what currently lies in the future but claims which we are not yet willing to make. Pending Projections are a record of what we may eventually be willing to say things are going to be like. Here is the view which re-presents Pending Projections. With the suffix Pend_Proj standing for pending projections it looks like this CREATE VIEW Policy_Pend_Proj AS SELECT oid asr_beg_dt asr_end_dt eff_beg_dt eff_end_dt client type copay what we used to claim what we currently claim what we will claim what things used to be like what things are like .