selection in relational semantics

Ngày tải lên: 17/03/2014, 08:20

... smoking habits in the cases should similarly affect assessment of smoking habits in the control group, 1 however, insisting on a dead control group violates the study base principle, since ... control selection design by comparing the consistency between the new design and a routine design in a large case-control study that was incorporated into a nationwide mortality survey in China. ... novel control selection design by comparing the consistency between the new design and a routine control selection design in a large case-control study that was incorporated into a nationwide...

Ngày tải lên: 26/10/2012, 09:48

... always wins among the routes actually installed in the routing table, while the routing protocol with the lowest administrative distance always wins when installing routes into the routing table. Cisco ... Contents Route Selection in Cisco Routers 1 Introduction 1 Processes Involved 1 Building the Routing Table 1 Backup Routes 2 Adjusting the Administrative Distance 2 Prefix Lengths 3 Making Forwarding Decisions ... 4 Summary 5 Tools Information 6 Related Information 6 Cisco − Route Selection in Cisco Routers i Route Selection in Cisco Routers Introduction Processes Involved Building the Routing Table Backup...

Ngày tải lên: 13/11/2012, 11:22

... described in [ONG84]. Our initial experience with the system is that dynamic linking is not preferable to static linking. One problem is that initial loading of routines is slow. Also, the ADT routines ... coordinates (0, 1, 0, 1). The following is a compact representation of this request in QUEL: 2 installation wants at the time the DBMS is installed. In this case, all routines could be linked into ... integer, floating point number, char- acter string) and built -in operators (e.g. +, -, *, /) were motivated by the needs of business data processing applications. However, in many engineering applications...

Ngày tải lên: 22/10/2013, 10:15

Ngày tải lên: 11/12/2013, 23:51

... 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 ... systems used in education, finance, health care, insurance, manufacturing, retailing and transportation—all industries in which the authors have had consulting experience. In using these methods, ... along inflow pipelines, and posted transactions as data destined for some kind of logfile, and as moving towards that destination along outflow pipelines. So if we can bring pending transactions into...

Ngày tải lên: 24/12/2013, 02:16

... 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 pressure increased to ... updating of warehouses, to real-time transactional updating. Data Cubes The first of these three developments is of minimal interest because it is pure technology, involving no advance in the semantics ... first restoring them from off-line storage media. After that, the next step was to realize that there was value, not just in having a par- ticular set of backup data remain on-line, but also in having...

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 ... of choosing one or more rows from a target table by specifying selection criteria, projecting one or more columns by listing the columns to be included in the query’s result set, and joining from ... 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 increasingly...

Ngày tải lên: 24/12/2013, 02:16

... designing and maintaining data models that must explicitly define temporal data structures and integrity constraints on them. It also relieves developers of the burden of designing, writing and maintaining ... lacking a standard for the PERIOD datatype, we will continue the practice of defining periods of time in terms of their begin and end points in time. Chapter 3 THE ORIGINS OF ASSERTED VERSIONING: ... represented in an asserted version 48 Part 2 AN INTRODUCTION TO ASSERTED VERSIONING which contains data destined for production tables are inflow pipeline datasets. Pipeline datasets which contain data...

Ngày tải lên: 24/12/2013, 02:16

... just one kind of internalized pipeline dataset, and the internalization of pipeline datasets can eliminate a large part of the IT maintenance budget by eliminating the need to manage pipeline datasets ... perhaps joining data that the production queries did not have to join, perhaps assembling intermediate results and then combining those intermediate results in various complicated ways. In short, ... is the SQL statement that inserted or most recently altered the data in that table. In each table, primary key columns are indicated by under- lining their column headings. In each table, the italicized...

Ngày tải lên: 24/12/2013, 02:16

... objects monitored by instruments, such as atomic nuclei or automobile engines. The objects that businesses are interested in generally fall in the mid-range in terms of being static or dynamic. Both ... a business user says that a policy should be deleted, she is (or should be) making a business statement. She is saying that as of a given point in time, the policy is no longer in effect. In a ... semantic constraints on bi-temporal data as that data is maintained, Asserted Versioning makes queries against its tables nearly as easy to write as queries against conventional tables. In the final section...

Ngày tải lên: 24/12/2013, 02:16

... truth. Temporal Integrity Constraints The three integrity constraints in relational theory are entity integrity, referential integrity and domain integrity. Entity integ- rity insures that the ... 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. All rights of reproduction in any form ... business data in a row is no longer in effect. In other words, the date which is one clock tick past the last date on which the business data in a row is in effect. Asr-beg. Assertion begin date....

Ngày tải lên: 24/12/2013, 02:16

... within shared assertion time, even a single effective-time clock tick included in another version of that object already in the table. Most physical transactions against bi-temporal tables are inserts. ... are known. Perhaps in another insurance company, all policies stop being in effect at the end of each calendar year. In that case, instead of an effective end date of 12/31/9999 in rows 1 and 3, ... with, the possibility of misinterpretation, on the maintenance side of things, is minimized. But what about the query side of things? What about looking at the data in an asserted version table?...

Ngày tải lên: 24/12/2013, 02:16

... SCENARIO 153 PART 3 DESIGNING, MAINTAINING AND QUERYING ASSERTED VERSION DATABASES Chapter Contents 8. Designing and Generating Asserted Versioning Databases 167 9. An Introduction to Temporal ... of “filling in the gap” between those two episodes, merging them into a single episode. In this chapter, however, we assume that our temporal insert creates a new episode. An episode begin date ... referential integrity on those tables. If ERwin is used as the data modeling tool, then a set of ERwin 162 Part 3 DESIGNING, MAINTAINING AND QUERYING ASSERTED VERSION DATABASES Note that, like...

Ngày tải lên: 21/01/2014, 08:20

... that each business key points to one and only one object by defining a unique index on it. Nor can we simply extend the scope of the index by defin- ing a unique index on the business key plus ... Table. Chapter 8 DESIGNING AND GENERATING ASSERTED VERSIONING DATABASES 173 8 DESIGNING AND GENERATING ASSERTED VERSIONING DATABASES CONTENTS Translating a Non-Temporal Logical Data Model into a Temporal Physical ... that correspond to rows in a conventi onal table of persistent objects. 164 Part 3 DESIGNING, MAINTAINING AND QUERYING ASSERTED VERSION DATABASES In this chapter, we focus on index design, although...

Ngày tải lên: 21/01/2014, 08:20

... 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 like the ... 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, ... copay of $15.” In other words, th e row sh ow n in Figure 9.2, as included in its first temporal container, has been placed in a second temporal container, and is treated as representing w hat we...

Ngày tải lên: 21/01/2014, 08:20

... 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 withdrawing them into past ... shown in Figure 10.3. Episode C, as we have labeled it, is a single-version episode. Of course all episodes, when initially created, are single-version episodes. Using the in- line notation introdu ... integrity or a referential integrity constraint, it will reject that transaction. In response, the AVF will stop processing the temporal transaction, undo Managing Time in Relational Databases. Doi:...

Ngày tải lên: 21/01/2014, 08:20

Ngày tải lên: 21/01/2014, 08:20

Ngày tải lên: 21/01/2014, 08:20

Ngày tải lên: 21/01/2014, 08:20