Practical exercise unit 7 Topic : MapReduce program in Java Work purpose : Display function, convolution function and the assignment perform the code study

Data writing get
File system class files of creation one how many methods own into takes _ Most simple method Path object takes created file and data written exit flow returns :
public FSDataOutputStream create ( F Path ) IOException the throws _
This of the method too much except loaded versions there is files for mandatory replacement flag , files replication write the coefficient clipboard the size of the file of the block size and access permissions installation enable gives _
to add operation one writing get source already writing received the file to change possibility gives ; Of this for file will open and data maximum offset with is written . With this API infinite in length files which creates applications ( eg magazine _ files ) from closing after there is to the file information to add can _ Add operation all Hadoop files systems by done is not increased . For example , add HDFS supports _ _ but S 3 files systems does not support .
Hadoop file to the system how to copy shows . of the operation to go show for we each Let's point to the progress() method in Hadoop calls - this each a 64K data package data node to the pipe written after happen will be
Control questions :
1. Efficiency to manage what are is included ?
2. Errors of management purpose what _
3. What for configuration manage do you need
4. Data protection to do of management purpose what _
5. Data protection to do manage lower system how tasks does ?
6. Network suitability concept define _
PRACTICAL EXERCISE UNIT-12


Subject : File from the system information get


Work target : FileSystem of the class getFileStatus () method study _


File metadata: FileStatus
Any _ file system directory from the structure transition and in it saved files and catalogs about information get ability support need _ FileStatus class Files and catalogs about file system metadata , including file _ length , block size , replication factor , change time , the owner information and access permits cover takes _ FileSystem of the class getFileStatus () method FileStatus object get method present is enough one file or directory for . Usage an example is in Listing 3.5 shown .


If the argument file If it shows , the method the most simple version FileStatus objects line returns _ length 1. If the argument is a directory in the directory files and catalogs expressive zero or from him over ¬ FileStatus objects will be returned .
Too bad except loaded versions files and catalogs choose for the filter defines PathFilter from the object pass can _ An example is in the "Path - Filter " section given , with . 108. Finally , one series roads in transfer the result equivalent " one path " method listStatus to call for simplified is a sign . FileStatus objects of arrays accumulation with each one road for consecutively one in the array . An example for , this feature file system of the tree different from the parts files the list Create for useful to be can _ Listing 3.6, this of your opinion simple demonstration gives _ FileUtil from the stat 2 Paths() method of class to use attention give FileStatus objects line rotate for Path objects to array .