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courses:mapreduce-tutorial:step-24 [2012/01/27 23:46] straka |
courses:mapreduce-tutorial:step-24 [2012/01/27 23:48] straka |
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We start by going through a simple Hadoop job with Mapper only. | We start by going through a simple Hadoop job with Mapper only. | ||
- | A mapper which processes (key, value) pairs of types (Kin, Vin) and produces (key, value) pairs of types (Kout, Vout) must be a subclass of [[http:// | + | A //mapper// which processes (key, value) pairs of types (Kin, Vin) and produces (key, value) pairs of types (Kout, Vout) must be a subclass of [[http:// |
The mapper must define a '' | The mapper must define a '' | ||
Line 80: | Line 80: | ||
</ | </ | ||
- | Remarks: | + | === Remarks |
* The filename //must// be the same as the name of the class -- this is enforced by Java compiler. | * The filename //must// be the same as the name of the class -- this is enforced by Java compiler. | ||
* In one class multiple jobs can be submitted, either in sequence or in parallel. | * In one class multiple jobs can be submitted, either in sequence or in parallel. |