Workflows expressed in Oozie can contain:

A.
Iterative repetition of MapReduce jobs until a desired answer or state is reached.

B.
Sequences of MapReduce and Pig jobs. These are limited to linear sequences of actions with
exception handlers but no forks.

C.
Sequences of MapReduce jobs only; no Pig or Hive tasks or jobs. These MapReduce
sequences can be combined with forks and path joins.

D.
Sequences of MapReduce and Pig. These sequences can be combined with other actions
including forks, decision points, and path joins.

Explanation:
Reference:http://incubator.apache.org/oozie/docs/3.1.3/docs/WorkflowFunctionalSpec.html(workfl
ow definition, first sentence)