reduceContext.key
Property Description |
When the map/reduce process includes a map stage, the reduce keys are the keys written by mapContext.write(options). When the map stage is skipped, the reduce keys are provided by the getInputData stage:
Note:
Each key cannot exceed 4000 bytes. |
Type |
string |
Since |
2015.2 |
Syntax
The following code snippet shows the syntax for this member. It is not a functional example. For a complete script example, see Map/Reduce Script Samples.
...
function reduce(context)
{
context.write({
key: context.key ,
value: context.values.length
});
}
...