Tài liệu Managing time in relational databases- P13 pdf

... than instances, is a relationship between two relational Managing Time in Relational Databases. Doi: 10.1016/B978-0-12-375041-9.00011-X Copyright # 2010 Elsevier Inc. All rights of reproduction in ... par- tially included in that timespan, those being the ones at the begin and/or end of the timespan. This delete transaction carries out a {split} transformation on the episode in...

Ngày tải lên: 21/01/2014, 08:20

... effective time than assertion time, we also present an in- line notation for single asserted Managing Time in Relational Databases. Doi: 10.1016/B978-0-12-375041-9.00006-6 Copyright # 2010 Elsevier Inc. ... integrity constraints in relational theory are entity integrity, referential integrity and domain integrity. Entity integ- rity insures that the object represented by a row...

Ngày tải lên: 24/12/2013, 02:16

... against non-temporal tables insert, update or delete individual rows representing objects, transactions against asserted version tables insert into a period of time, update within a period of time, ... their destinations or their origins. Deferred assertions are the result of applying deferred trans- actions to the database. Instead of holding on to maintenance Part 3 DESIGNING, MAINTAINING...

Ngày tải lên: 21/01/2014, 08:20

... effective time it affects. As a relationship between a point in time and a period of time, the basic options are that the point in time can be earlier than the period of time, within the period of time, ... will continue on, and will update the database. In doing so, it will begin by preserving the original state of the version or versions about to be changed, doing this by wit...

Ngày tải lên: 21/01/2014, 08:20

... available. By internalizing these datasets within the production tables whose data they contain, we eliminate the costs of managing them, including the costs of recovering from mistakes made in managing ... is currently asserted as being currently in effect, this view also contains one row per object. In addition, since, at every point in time, the original table contains rows t...

Ngày tải lên: 21/01/2014, 08:20

... thing to note here is that we get to this starting point in the search of the index without doing a scan. Our strategy is to get to the desired result using an index with little or no scanning. Once ... fil- tering on effective begin date, the index will be scanned for the 356 Chapter 15 OPTIMIZING ASSERTED VERSIONING DATABASES remaining criteria including assertion begin date. And the same...

Ngày tải lên: 26/01/2014, 08:20

... query. Components: external pipeline dataset, internalized pipeline dataset. point in time Mechanics: a time period whose begin date value, using the closed-open representation of time periods, is one clock ... physically present in the table as of that point in time. The contents of a semantic logfile of that table, as of that point in time, are all those rows asserted on or...

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

... 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