  Datalog^E is the extension of Datalog with existential quantification. While
its high expressive power, underpinned by a simple syntax and the support for
full recursion, renders it particularly suitable for modern applications on
knowledge graphs, query answering (QA) over such language is known to be
undecidable in general. For this reason, different fragments have emerged,
introducing syntactic limitations to Datalog^E that strike a balance between
its expressive power and the computational complexity of QA, to achieve
decidability. In this short paper, we focus on two promising tractable
candidates, namely Shy and Warded Datalog+/-. Reacting to an explicit interest
from the community, we shed light on the relationship between these fragments.
Moreover, we carry out an experimental analysis of the systems implementing Shy
and Warded, respectively DLV^E and Vadalog.
