Hadoop
Why do we need to set the output key/value class explicitly in the Hadoop program?
In the \"Hadoop : The Definitive Guide\" book, there is a sample program with the below code. JobConf conf = new JobConf(MaxTemperature.class);[详细]
2023-04-05 11:38 分类：问答Running certain Hadoop Jobs only on a chosen node and not in the others, managing the process with Oozie
Is that even possible? I\'ve searched quite a bit and I\'d say it\'s not possible, but开发者_JS百科 I think it\'s so strange a so basilar functionality has not been foreseen.[详细]
2023-04-05 10:50 分类：问答What is the purpose of the org.apache.hadoop.mapreduce.Mapper.run() function in Hadoop?
What is the purpose of the org.apache.hadoop.mapreduce.Mappe开发者_StackOverflow中文版r.run() function in Hadoop? The setup() is called before calling the map() and the clean() is called after the map[详细]
2023-04-05 10:26 分类：问答whether method cancel() and method interrupt() do the duplicate job?
I read the source of org.apache.nutch.parse.ParseUtil.runParser(Parser p, Content content). Do these two method calls do the same thing:[详细]
2023-04-05 05:35 分类：问答How to tell MapReduce how many mappers to use?
I am trying to speed optimize MapReduce job. Is there any way I can tell hadoop to use a particular number of mapper/reducer processes? Or, at least, minimal number of mapper processes?[详细]
2023-04-05 01:04 分类：问答Refer to base types that have a raw type constraint
I\'ve been playing around with Scala, trying to get SMR to compile in Scala IDE with 2.9.1.SMR seems to have gone untouched since 2008-ish, and there are a lot of unresolved compile errors.The one tha[详细]
2023-04-04 22:08 分类：问答hadoop streaming ensuring one key per reducer
I have a mapper that, while processing data, classifies output into 3 different types (type is the output key). My goal is to create 3 different csv files via the reducers, each with all of the data f[详细]
2023-04-04 22:00 分类：问答What is the best way of reading/writing binary input/output files with MapReduce?
In all samples I\'ve seen so far, mapreduce apps take text files as input and write text as output. I\'d like my app to 开发者_开发知识库read objects from the binary file and write objects back to ou[详细]
2023-04-04 21:02 分类：问答Sequential Files in Hadoop
How to read/parse a Sequential File written by previous Map Reduce Job. The keyOut and ValueOut of prev MR Job were Text and ByteWritable. What should be the keyin and valuein for the mapper of my nex[详细]
2023-04-04 16:18 分类：问答java.lang.RuntimeException: java.lang.ClassNotFoundException when trying to run Jar job on Elastic MapReduce
What should I change to fix following error: I\'m trying to start a job on Elastic Mapreduce, and it crashes every time with message:[详细]
2023-04-04 04:18 分类：问答
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