Tài liệu Managing time in relational databases- P3 doc

... point in time forward to the point in time we are interested in. But the defining feature of reconstructable methods is not the movement of data from off-line to on-line storage. The defining ... waiting for the data, and the decisions delayed until the data becomes available. In an increasingly fast-paced business world, the opportunity cost of delays in accessing data is incre...

Ngày tải lên: 24/12/2013, 02:16

... bigint eff_beg_dt: datetime asr_beg_dt: datetime wellpgmcat_oid: bigint eff_beg_dt: datetime eff_end_dt: datetime asr_end_dt: datetime row_crt_dt: datetime client_wellpgm_oid: bigint eff_beg_dt: datetime asr_beg_dt: ... tables in those databases into bi-temporal asserted Managing Time in Relational Databases. Doi: 10.1016/B978-0-12-375041-9.00008-X Copyright # 2010 Elsevier Inc. Al...

Ngày tải lên: 21/01/2014, 08:20

... taxonomy in terms of its topology. On a line representing a timeline, we can place a line segment representing an episode. We can also remove a line segment from that line. Given a line segment, ... significantly reduces the work involved in maintaining temporal data, and will eliminate the errors that would otherwise inevitably happen as temporal data is maintained. Using a framework lik...

Ngày tải lên: 21/01/2014, 08:20

... dates. Time Period to Time Period Queries Allen relationships may relate two time periods, or a time period to a point in time, or two points in time. We will represent time periods, using our ... currently claim were in effect any time in the first half of 2008. Pinning down a point in assertion time, and then asking for versions of objects claimed at that point in...

Ngày tải lên: 21/01/2014, 08:20

... OTHER QUERIES Point in Time to Period of Time Queries A point in time is a period of time that includes only one clock tick. Thus, using the closed-open convention, a point in time, T 1 , is identical ... relationships, and taxonomic groupings of them, between pairs of time periods, between a time period and a point in time, and between two points in time. Once again,...

Ngày tải lên: 21/01/2014, 08:20

... the lower cardinality columns. Clustering would continue based on 3 Low cardinality means that there are fewer distinct values for the field in the table which results in more rows having a single value. Chapter ... querying. There is no delay between the business request for data, and its availability in queryable form. The majority of queries against bi-temporal data are point -in- t...

Ngày tải lên: 26/01/2014, 08:20

... d by their starting point in time and ending point in time. These points in time may be timestamps, dates, or any other point in time recognizable by the DBMS. As defined in this Glossary, they ... origin of data ware- housing in just as incontrovertible a sense as Dr. E. F. Codd’s early articles were the origins of relational theory. 1996: Building the Data Warehouse Wil...

Ngày tải lên: 26/01/2014, 08:20

... relationships between two time periods, a time period and a point in time, or two points in time, as first defined in James F. Allen’s 1983 article Maintaining Knowledge about Temporal Intervals. Semantics: ... transition from one point in effective time or assertion time to the next point in effective time or assertion time, according to the chosen granularity which de...

Ngày tải lên: 26/01/2014, 08:20

... data in which none of that is necessary, a world in which all pipeline datasets are contained in the single table that is their destination or their point of origin. In this world, maintaining ... useful by integrating them into larger patterns. But he has worked in the world of business IT for his entire career. And in that world, theory is fine, but it must xx PREFACE MANAGING...

Ngày tải lên: 24/12/2013, 02:16

... Versioning Asserted Versioning Framework (AVF) xxii PREFACE row the query author is interested in, two of those components being time periods that may or may not intersect in various ways. Continuing ... management losing faith in data warehouse projects. As these large projects fell increasingly behind schedule and rose increasingly over budget— something large projects tend to do—the...

Ngày tải lên: 24/12/2013, 02:16