# algorithm « hadoop « Java Database Q&A

### 1. how to implement eigenvalue calculation with MapReduce/Hadoop?    stackoverflow.com

It is possible because PageRank was a form of eigenvalue and that is why MapReduce introduced. But there seems problems in actual implementation, such as every slave computer have to maintain ...

### 2. How does the MapReduce sort algorithm work?    stackoverflow.com

One of the main examples that is used in demonstrating the power of MapReduce is the Terasort benchmark. I'm having trouble understanding the basics of the sorting algorithm used ...

### 3. Efficient search in a corpus    stackoverflow.com

I am having a few million words which I want to search in a billion words corpus. What will be the efficient way to do this. I am thinking of a trie, ...

### 4. Hadoop for super O(N) or O(N log N) algorithms?    stackoverflow.com

Is there any documented case of Hadoop working for any algorithm that's more than approximately linear? Or does huge data sets pretty much mean that anything above linear is unacceptable? I'm trying ...

### 5. ClassNotFoundException error in implementing Bayesian algorithm in Apache Mahout on Hadoop    stackoverflow.com

I have a problem in executing the Bayesian algorithm in Mahout. I built it with Maven and the job file is in target directory. When run from terminal using hadoop, I'm ...

### 6. fft algorithm implementation with hadoop    stackoverflow.com

I want to implement Fast Fourier Transform algorithm with Hadoop. I know recursive-fft algorithm but I need your guideline in order to implement it Map/Reduce approach. Any suggestions? Thanks.

### 7. Map-Side Join Algorithm for MapReduce    stackoverflow.com

I am trying to use the Hadoop's Map-side join using CompositeInputFormat but I get an IOException: "Unmatched ')'". I guess there may be a problem in the format of my input ...

### 8. Hadoop Map Reduce: Algorithms    stackoverflow.com

Can someone point me to a good web site with good collection of Hadoop algorithms. For example, the most complex thing that I can do with Hadoop right now is Page ...

### 9. Efficient Phrase Matching Algorithm    stackoverflow.com

I have a set of about 7 Million phrases to be matched to about 300 Million queries. Queries can be sub-strings or contain the phrases themselves. Basically I want a measure ...

### 10. All pairs all paths on a graph    stackoverflow.com

This is possibly a problem with possibly no optimal solution. Suppose I have a directed graph, have no clue whether it has any cycles or not(cycle detection will be one of ...

### 11. Hadoop gzip compressed files    stackoverflow.com

I am new to hadoop and trying to process wikipedia dump. It's a 6.7 GB gzip compressed xml file. I read that hadoop supports gzip compressed files but can only be ...

### 12. Map Reduce algorithm for removing cycles from a graph    stackoverflow.com

This question has a great answer for detecting cycles in a directed graph. Unfortunately, it does not seem easy to make a Map Reduce version of it. Specifically, ...

### 13. Suggestions needed for optimizing O(n^2) algorithm    stackoverflow.com

I am looking to optimize a fairly simple algorithm that is currently O(n2). I have a file of records, where each one needs to be compared to every other in the same ...

### 14. Can brute force algorithms scale?    stackoverflow.com

I have a math problem that I solve by trial and error (I think this is called brute force), and the program works fine when there are a few options, but ...

### 15. Implementing custom algorithm on the top of hadoop using eclipse plugin    stackoverflow.com

We are implementing BoW algorithm from a Data Mining Paper. The algorithm chooses one of the two algorithms (ParC ans SnI), depending upon the data-set in order to reduce input-output cost ...