Hadoop Merging vs Reducing

The merging and reducing operations in Hadoop are two distinct actions.

Merge refers to combining multiple small files or data blocks into a larger file or data block in order to reduce the number of files or improve data processing efficiency. In Hadoop, MapReduce jobs generate multiple intermediate result files, which need to be merged in order to reduce the number of files and improve the efficiency of subsequent processing.

In the Reduce stage of Hadoop, the intermediate results from the Map stage are aggregated and computed together to produce the final result.

Therefore, merging is the act of combining files or data blocks, while reducing involves merging and calculating data. Although both involve merging operations, they have different targets and purposes.