UNIT-1

TOPICS TO BE DISCUSSED

1)External Sorting
2)K-Way Merging
3)Buffer Handing for parallel Operation
4)Run Generation
5)Optimal Merging Of Run

External Sorting:

what is Sorting?

The process of arranging the elements either in the ascending order or in the descending can be called as "Sorting"

Types of Sorting:
This sorting can be classified into two types:
1)External Sorting
2)Internal Sorting

External Sorting:

It is the process which is used when the number of elements or records to be sorted are in large number,such that all of them can not be accommodated in the internal memory of computer.therefore

the files containing huge records or files to be sorted will be stored on external storage  devices and external storage process is applied.

Internal Sorting

It is the process which is usually used when the records to be sorted
are less in number.

External Sorting Process:

It performs the following steps:-

a)It collects the records from the external storage and kept into the internal memory.

b)In order to generate "runs" apply internal sort algorithms on those records

c)write those "runs" onto the external storage devices.

d)merge the "runs" generated in the previous(above)steps 

e)repeat steps b,c and d untill all runs are merged and we are left with a single run in  which the file containg all the records in sorted order.