Single mapper jobs are used in transformation use cases. If we want to change only the format of data, such as some kind of transformation, then this pattern is used:
|
Scenario |
Some cities have short names as BOS, NYC, and so on |
|
Map (Key, Value) |
Key: city Name Value: ShortName → if city is Boston/boston then converted to BOS else if city is New York/new york then convert to NYC |
Now, let's look at a complete example of a Single mapper only job. For this, we will simply try to output the cityID and temperature from the temperature.csv file seen earlier.
The following is the code:
package io.somethinglikethis; ...
