Old and new MapReduce APIs

The new API (which is also known as Context Objects) was primarily designed to make the API easier to evolve in the future and is type incompatible with the old one.

The new API came into the picture from the 1.x release series. However, it was partially supported in this series. So, the old API is recommended for 1.x series:

Feature\Release

1.x

0.23

Old MapReduce API

Yes

Deprecated

New MapReduce API

Partial

Yes

MRv1 runtime (Classic)

Yes

No

MRv2 runtime (YARN)

No

Yes

The old and new API can be compared as follows:

Old API

New API

The old API is in the org.apache.hadoop.mapred package and is still present.

The new API is in the org.apache.hadoop.mapreduce package.

The old API used interfaces for Mapper ...

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