selection in relational semantics
Báo cáo y học: "Comparative study of control selection in a national population -based case-control study: Estimating risk of smoking on cancer deaths in Chinese men"
Ngày tải lên :
26/10/2012, 09:48
... 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...
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Tài liệu mở rộng quản trị mạng IP Routing Route Selection in Cisco Routers
Ngày tải lên :
13/11/2012, 11:22
... 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...
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Inclusion of new types in relational database systems
Ngày tải lên :
22/10/2013, 10:15
... 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...
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Tài liệu Managing time in relational databases- P1 ppt
Ngày tải lên :
24/12/2013, 02:16
... 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...
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Tài liệu Managing time in relational databases- P2 pptx
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...
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Tài liệu Managing time in relational databases- P3 doc
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...
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Tài liệu Managing time in relational databases- P4 pptx
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...
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Tài liệu Managing time in relational databases- P5 pptx
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...
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Tài liệu Managing time in relational databases- P6 pptx
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...
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Tài liệu Managing time in relational databases- P7 pdf
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....
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Tài liệu Managing time in relational databases- P8 pptx
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?...
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Tài liệu Managing time in relational databases- P9 pdf
Ngày tải lên :
21/01/2014, 08:20
... 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...
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Tài liệu Managing time in relational databases- P10 docx
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...
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Tài liệu Managing time in relational databases- P11 doc
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...
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Tài liệu Managing time in relational databases- P12 pdf
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:...
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