Reference no: EM131212125
In Example 23.11 we observed that if all we wanted was the maximum of N temperature readings in a sliding window of time-temperature tuples, then when a reading of t arrives, we can delete immediately any earlier reading that is smaller than t.
a) Does this rule always compress the data in the window?
b) Suppose temperatures are real numbers chosen uniformly and at random from some fixed range of values. On average, how many tuples will be retained, as a function of N?
Example 23.11
Suppose we would like to know, for each sensor, the highest recorded temperature to arrive at the DSMS in the past hour. We form the appropriate time-based window and query it as if it were an ordinary relation. The query looks like:
This query can be issued as an ad-hoc query, in which case it is executed once, based on the window that exists at the instant the query is issued. Of course the DSMS must have made available to the query processor a window on Sensors of at least one hour's length.2 The same query could be a standing query, in which case the current result relation should be maintained as if it were a materialized view that changes from time to time. In Section 23.4.5 we shall consider an alternative way to represent the result of this query as a standing query.
|
Evaluate how these designs have been used
: You consider the different research designs and evaluate how these designs have been used to research a specific topic. You also consider strategies for selecting an appropriate research design.
|
|
Summarize the five-step model for ethical problem solving
: Summarize the Five-Step Model for ethical problem solving. Do you think it is useful for practical decision-making in the context of health care? Why or why not?
|
|
Current implementation and concerns
: Parent domain (kris.local) and child domain (corp.kris.local) for the organization's AD infrastructure are running on Server 2008. The following are concerns related to AD: (1) Kris Corporation is concerned about running multiple domain, and (2) a..
|
|
Create a pamphlet for families
: Provide sources of information for parents who need support in the IEP and IFSP processes (websites, parent information networks, support services, etc.). State education sites are good sources of information.
|
|
Does this rule always compress the data in the window
: Suppose temperatures are real numbers chosen uniformly and at random from some fixed range of values. On average, how many tuples will be retained, as a function of N?
|
|
Video expect the internet to have on government
: What changes did the people in the video expect the Internet to have on government? Which predictions and/or what perceptions proved true and which ones did not? Explain why the Internet fell short of expectations in terms of its impact on politics..
|
|
Evaluate the overall thoughtfulness and quality of your blog
: I am interested in your reaction to the film, your analysis of why it was moving, compelling, boring, redundant, exciting for you, and why. I will evaluate the overall thoughtfulness and quality of your blog responses.
|
|
What is the arrival rate, assuming d/d/1 queuing
: If the queue dissipates 8 seconds before the end of the cycle and the cycle length is 60 seconds, what is the arrival rate, assuming D/D/1 queuing?
|
|
How that reasoning supports position you think is strongest
: Explain the kind of reasoning you think is the best way to approach this question, and how that reasoning supports the position you think is strongest.
|