Mapper « hadoop « Java Database Q&A

1. hadoop mapper static initialisation    stackoverflow.com

I have a code fragment in which I am using a static code block to initialize a variable.

public static class JoinMap extends 
        ...

2. Hadoop- Basic question regarding input to the mapper function    stackoverflow.com

We can provide input files to the mapper as FileInputFormat.setInputPaths(conf, inputPath); Is it possible to pass a reference to memory say a DOM tree constructed using a DOM parser after parsing an ...

3. Pass file location as value to hadoop mapper?    stackoverflow.com

Is it possible to pass the locations of a files in HDFS as the value to my mapper so that i can run an executable on them to process them?

4. Using a .exe as part of mapper (Hadoop)    stackoverflow.com

I am writing a mapreduce job to process binary log files. An executable is needed to process the file before the relevent information can be obtained.Is the java process builder the ...

5. Get the input path in a Hadoop Mapper Class    stackoverflow.com

I have implemented a simple MapReduce project in Hadoop for processing logs. The input path is the directory where the logs are. It works fine but I would like to ...

6. printing to screen variables inside mapper    stackoverflow.com

I want to check the contents of an element that is in my map functions, is there a way to print the contents of the variables to the screen. It is very slow ...

7. The type Mapper is not generic, hadoop eclipse pluggin    stackoverflow.com

I am using eclipse to write mapreduce program. I imported hadoop library (hadoop-0.13.0-core.jar) I imported Mapper class import org.apache.hadoop.mapred.Mapper; there is no error in this but when I wrote this program source of this ...

8. Why not mapper/reducer for hadoop TeraSort    stackoverflow.com

I am planning to insert some code into the mapper of the TeraSort class in Hadoop 0.20.2. However, after reviewing the source code, I cannot locate the segment that mapper is ...

9. Writing only the Value on Mapper Job    stackoverflow.com

I am currently working on a MapReduce Job which I am only using the mapper without the reducer. I do not need to write the key out because I only need ...

10. Sending a variable to the Mapper Class    stackoverflow.com

I am trying to get an input from the user and pass it to my mapper class that I have created but whenever the value always initialises to zero instead of ...

11. How to design my mapper?    stackoverflow.com

I have to write a mapreduce job but I dont know how to go about it, I have jar MARD.jar through which I can instantiate MARD objects. Using which I call the ...

12. How to make your mapper write on local file system in hadoop    stackoverflow.com

I wish to write a file and create a directory in my local file system through m MapReduce code. Also if I create a directory in the working directory during the ...

13. How does hive/hadoop assures that each mapper works on data that is local for it?    stackoverflow.com

2 basic questions that trouble me:

• How can I be sure that each of the 32 files hive uses to store my tables sits on its unique machine?
• If that happens, how can ...

14. Hadoop gzip input file using only one mapper    stackoverflow.com

Possible Duplicate:
Why can't hadoop split up a large text file and then compress the splits using gzip?

15. Hadoop java mapper -copyFromLocal heap size error    stackoverflow.com

As part of my Java mapper I have a command executes some code on the local node and copies a local output file to the hadoop fs. Unfortunately I'm getting ...

16. MapReduceBase and Mapper deprecated    stackoverflow.com

public static class Map extends MapReduceBase implements Mapper

17. How to pass object to Mapper and reducers    stackoverflow.com

I have an application run on hadoop. How can I pass the objects to the mappers and reducers so as to process the data. For example, I declare a FieldFilter object ...