1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
bonufazy [111]
3 years ago
7

A particular Table in a relational database contains 100,000 Data Records/rows, each of which Data Record/row requires 200 bytes

. A select statement returns all Data Records/rows in the Table that satisfy an equality search on an attribute. Estimate the time in milliseconds to complete the query when each of the following Indexes on that attribute is used.
A. No Index (Heap File of Data Records)
B. A Static Hash Index (with no overflow buckets/Pages). Assume the cost of applying the hash function is H, negligible.
Engineering
1 answer:
MrRa [10]3 years ago
3 0

The correct question is;

A particular table in a relational database contains 100,000 rows, each of which requires

200 bytes of memory. Estimate the time in milliseconds to to insert a new row into the

table when each of the following indices on the related attribute is used. Assume a page

size of 4K bytes and a page access time of 20 ms.

a. No index (heap file)

b. A clustered, non-integrated B+ tree index, with no node splitting

required. Assume that each index entry occupies 100 bytes. Assume that the

index is 75% occupied and the actual data pages are 100% occupied. Assume

that all matching entries are in a single page.

Answer:

A) 20 ms

B) 120 ms

Explanation:

A) Append (at the end of file). Just one IO, i.e., 20 ms

B) Now, when we assume that each entry in the index occupies 100 bytes, then an index page can thus hold 40 entries. Due to the fact that the data file occupies 5000 pages, the leaf level of the tree must contain at least 5000/40 pages which is 125 pages.

So, the number of levels in the tree (assuming page 75% occupancy in the

index) is (log_30 (125)) + 1 = 3. Now, if we assume that the index is clustered and not integrated with the data file and all matching entries are in a single

page, then 4 I/O operations and 80ms are required to retrieve all matching

records. Two additional I/O operations are required to update the leaf page

of the index and the data page. Hence, the time to do the insertion is

120ms.

You might be interested in
Imagine that you are the architect that designed the school. Identify five safety hazards that should be included in the design
ankoles [38]

Answer:

Access for physically disabled students and staff, fire hazards / fire escape hazards for stairs and elevators, emergency escapes...and that's all I can think of.

4 0
3 years ago
Convert 25 inches / min to mm/hour​
Taya2010 [7]

Answer:

25 mins into hours = 0.416667 hours

25 inches as mm = 635

Explanation:

6 0
3 years ago
Which of the following sensors is used to provide suspension control module with feedback regarding vehicle cornering​ forces?
Readme [11.4K]

Answer:

A

Explanation:

4 0
3 years ago
Interpret the Blame responsibility and causation in your own words in the light of Columbia Accident.
Licemer1 [7]

Answer:

Proposed Improvements and Generic Lessons

Within 2 h of losing the signal from the returning spacecraft, NASA’s Administrator established the Columbia Accident Investigation Board (CAIB) to uncover the conditions that had produced the disaster and to draw inferences that would help the US space program to emerge stronger than before (CAIB, 2003). Seven months later, the CAIB released a detailed report that included its recommendations (Starbuck and Farjoun, 2005).

The CAIB (2003) report attempted to seek answers to the following four crucial questions:

1.

Why did NASA continue to launch spacecraft despite many years of known foam debris problems?

2.

Why did NASA managers conclude, despite the concerns of their engineers, that the foam debris strike was not a threat to the safety of the mission?

3.

How could NASA have forgotten the lessons of Challenger?

4.

What should NASA do to minimize the likelihood of such accidents in the future?

Although the CAIB’s comprehensive report raised important questions and offered answers to some of them, it also left many major questions unanswered (Starbuck and Farjoun, 2005).

1.

Why did NASA consistently ignore the recommendations of several review committees that called for changes in safety organization and practices?

2.

Did managerial actions and reorganization efforts that took place after the Challenger disaster contribute, both directly and indirectly, to the Columbia disaster?

3.

Why did NASA’s leadership fail to secure more stable funding and to shield NASA’s operations from external pressures?

By examining, with respect to the Columbia disaster, the case of NASA as an organization, one can try to extract generalizations that could be useful for other organizations, especially those engaged in high-risk activities—such as nuclear power plants, oil and gas, hospitals, airlines, armies, and pharmaceutical companies—and such generic principles may also be salutary for any kind of organization.

The CAIB (2003) report recommended developing a plan to inspect the condition of all RCC systems, the investigation having found the existing inspection techniques to be inadequate. RCC panels are installed on parts of the shuttle, including the wing leading edges and nose cap, to protect against the excessive temperatures of reentry. They also recommended that taking images of each shuttle while in orbit should be standard procedure as well as upgrading the imaging system to provide three angles of view of the shuttle, from liftoff to at least SRB separation. “The existing camera sites suffer from a variety of readiness, obsolescence, and urban encroachment problems.” The board offered this suggestion because NASA had had no images of the Columbia shuttle clear enough to determine the extent of the damage to the wing. They also recommended conducting inspections of the TPS, including tiles and RCC panels, and developing action plans for repairing the system. The report included 29 recommendations, 15 of which the board specified must be completed before the shuttle returned to flight status, and also made 27 “observations” (CAIB, 2005).

7 0
3 years ago
In a shear box test on sand a shearing force of 800 psf was applied with normal stress of 1750 psf. Find the major and minor pri
ryzh [129]

Answer:

The major and minor stresses are as 2060.59 psf, -310.59 psf and 1185.59 psf.

Explanation:

The major and minor principal stresses are given as follows:

\sigma_{max}=\dfrac{\sigma_x+\sigma_y}{2}+\sqrt{\left(\dfrac{\sigma_x-\sigma_y}{2}\right)^2+\tau_{xy}^2}

\sigma_{min}=\dfrac{\sigma_x+\sigma_y}{2}-\sqrt{\left(\dfrac{\sigma_x-\sigma_y}{2}\right)^2+\tau_{xy}^2}

Here

  • \sigma_x is the normal stress which is 1750 psf
  • \sigma_y is 0
  • \tau_{xy} is the shear stress which is 800 psf

So the formula becomes

\sigma_{max}=\dfrac{\sigma_x+\sigma_y}{2}+\sqrt{\left(\dfrac{\sigma_x-\sigma_y}{2}\right)^2+\tau_{xy}^2}\\\sigma_{max}=\dfrac{1750+0}{2}+\sqrt{\left(\dfrac{1750-0}{2}\right)^2+(800)^2}\\\sigma_{max}=875+\sqrt{\left(875)^2+(800)^2} \\\sigma_{max}=875+\sqrt{765625+640000}\\\sigma_{max}=875+1185.59\\\sigma_{max}=2060.59 \text{psf}

Similarly, the minimum normal stress is given as

\sigma_{min}=\dfrac{\sigma_x+\sigma_y}{2}-\sqrt{\left(\dfrac{\sigma_x-\sigma_y}{2}\right)^2+\tau_{xy}^2}\\\sigma_{min}=\dfrac{1700+0}{2}-\sqrt{\left(\dfrac{1700-0}{2}\right)^2+(800)^2}\\\sigma_{min}=875-\sqrt{(875)^2+(800)^2}\\\sigma_{min}=875-\sqrt{765625+640000}\\\sigma_{min}=875-1185.59\\\sigma_{min}=-310.59 \text{ psf}

The maximum shear stress is given as

\tau_{max}=\dfrac{\sigma_{max}-\sigma_{min}}{2}\\\tau_{max}=\dfrac{2060.59-(-310.59)}{2}\\\tau_{max}=\dfrac{2371.18}{2}\\\tau_{max}=1185.59 \text{psf}

5 0
3 years ago
Other questions:
  • The chief engineer at a university that is constructing large number of new student dormitories decides install a counterflow co
    12·1 answer
  • A speaker's knowledge of how he or she wants to affect the audience will be helpful in choosing the right information and influe
    7·1 answer
  • Explain why many sustainable fishing and forestry practice depend on the actions of consumers like you.
    13·2 answers
  • Air at 40C flows over a 2 m long flat plate with a free stream velocity of 7 m/s. Assume the width of the plate (into the paper)
    9·1 answer
  • HIIIIIIIIII htrdcvbnjuytresdxcvbnjhytrdefghjkmnbvcdertyhjmn i'm soo bored
    9·2 answers
  • How much wood could a wood chuck chuk if a wood chuck could chuck wood
    10·2 answers
  • Pointttttttttttttssssssssssss
    12·1 answer
  • What do we need to do to get CO2 emissions all the way to zero?
    5·1 answer
  • Determine the output logic-levels(boolean-levels) for XNOR if the two-inputs are inverted?​
    8·1 answer
  • Which of the following BEST represents the causes of stiff muscles?
    12·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!