What is Polyphase Sort, Data Structure & Algorithms

Assignment Help:
One of the best known methods for external sorting on tapes is the polyphase sort.

Principle: The basic strategy of this sort is to distribute ordered initial runs of predetermined size on the available tapes and then to repeatedly merge these runs in multiple phases in which each phase has a predetermined number of merges before a new target tape is selected.

To distribute the initial runs a Fibonacci distribution is adopted. After the distribution of the runs according to Fibonacci distribution, the merging procedure is continued until the tape with the least number of run lists is empty. When this occurs the remaining working tapes are logically rotated such that the newly emptied tape becomes the new target tape and the old target tape then becomes one of the working tapes to be merged. The sort ends when all runs are merged into one.

Let the number of tapes be T and p = T - 1. The Fibonacci distribution for p = 3 is given.

Level

s
Tape
Total number of runs
1
2
3
1
0
0
1
1
2
1
1
1
3
3
1
2
2
5
4
2
3
4
9
5
4
6
7
17
6
7
11
13
31
7
13
20
24
57
8
24
37
44
105
9
44
68
81
193
Algorithm:

1. Let A be the list of N unsorted elements and R be the number of runs.

2. Let T1, T2, T3 and T4 be the tapes on which sorting is done.

3. Split the list A into R=N runs so that each run has only one element.

4. If R is not equal to perfect Fibonacci distribution then add dummy records to bring up perfect Fibonacci distribution.

5. Distribute the records in the remaining tapes according to the Fibonacci distribution.

6. Merge 3 runs, one from each tape and put into next empty tape.

7. Repeat step 6 till a single run is generated.

Related Discussions:- What is Polyphase Sort

Write an algorithm outputs number of books using psuedocode, A shop sells b...

A shop sells books, maps and magazines. Every item is identified by a unique 4 - digit code. All books have a code starting with a 1, all maps have a code which starts with a 2 and

Er diagram, Ask queConsider the following functional dependencies: Applican...

Ask queConsider the following functional dependencies: Applicant_ID -> Applicant_Name Applicant_ID -> Applicant_Address Position_ID -> Positoin_Title Position_ID -> Date_Position_O

Write a program to create a heap file, Write a program to create a heap fil...

Write a program to create a heap file that holds the records in the file " data_2013 " The source records are variablelength.However, the heap file should hold fixed-length reco

Column major representation, Column Major Representation In memory th...

Column Major Representation In memory the second method of representing two-dimensional array is the column major representation. Under this illustration, the first column of

Determine the disjoint of division method, Determine the Disjoint of divisi...

Determine the Disjoint of division method A polygon is disjoint from the viewport if the x- and y-extents of the polygon do not overlap the viewport anywhere. In this case; reg

Write a program to create a hashed file, Write a program to create a hashed...

Write a program to create a hashed file that stores the records currently in the file " data_2013 ". Records should use the same fixed-length schema given previously, and should ag

Stack, Explain in detail the algorithmic implementation of multiple stacks....

Explain in detail the algorithmic implementation of multiple stacks.

Write an algorithm to input number of passengers travelling, There are ten ...

There are ten stations on a railway line: Train travels in both directions (i.e. from 1 to 10 and then from 10 to 1).  Fare between each station is $2. A passenger input

LINKED LIST, HOW LINKED LIST HEADER WORKS? HOW TO INSERT AND DELETE ELEMENT...

HOW LINKED LIST HEADER WORKS? HOW TO INSERT AND DELETE ELEMENTS IN LINKED LIST?

Queues, what is queues? how it work? and why it used? i want an assignment...

what is queues? how it work? and why it used? i want an assignment on queue .....

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd