MapReduce
| Entry point | Purpose of corresponding function | Required? |
| getInputData(inputContext) | To identify data that needs processing. The system passes this data to the next stage. | yes |
| map(mapContext) | To apply processing to each key/value pair provided, and optionally pass data to the next stage. | One of these (Map/reduce) two entry points is required. You can also use both entry points. |
| reduce(reduceContext) | To apply processing to each key/value pair provided. In this stage, each key is unique, and each value is an array of values. This function can optionally pass data to the summarize stage. | One of these (Map/reduce) two entry points is required. You can also use both entry points. |
| summarize(summaryContext) | To retrieve data about the script’s execution, and take any needed actions with the output of the reduce stage. | No |