Is dropping an edge property expected to drop its edge?

Question

With DSE v5.0.3, I've encountered a situation where dropping an edge property drops its edge as well.

Both of the gremlin console examples use the following schema configuration:

gremlin> system.graph('example').create()
==>null
gremlin> :remote config alias g example.g
==>g=example.g
gremlin> schema.propertyKey('notes').Text().single().create()
==>null
gremlin> schema.vertexLabel('person').create()
==>null
gremlin> schema.edgeLabel('knows').properties('notes').create()
==>null
gremlin> schema.edgeLabel('knows').connection('person', 'person').add()
==>null

In the following example, dropping the edge property results in the edge itself being dropped:

gremlin> person1 = g.addV('person').next()
==>v[{~label=person, community_id=1566048896, member_id=0}]
gremlin> person2 = g.addV('person').next()
==>v[{~label=person, community_id=1062113536, member_id=0}]
gremlin> knows = g.V(person1).addE('knows').to(V(person2)).property('notes', 'online').next()
==>e[{~type=knows, out_vertex={~label=person, community_id=1566048896, member_id=0}, in_vertex={~label=person, community_id=1062113536, member_id=0}, local_id=4cd8f8e2-a6b8-11e6-aa90-df2b21a156a2}][{~label=person, community_id=1566048896, member_id=0}-knows->{~label=person, community_id=1062113536, member_id=0}]
gremlin> g.E(knows)
==>e[{~type=knows, out_vertex={~label=person, community_id=1566048896, member_id=0}, in_vertex={~label=person, community_id=1062113536, member_id=0}, local_id=4cd8f8e2-a6b8-11e6-aa90-df2b21a156a2}][{~label=person, community_id=1566048896, member_id=0}-knows->{~label=person, community_id=1062113536, member_id=0}]
gremlin> g.E(knows).properties('notes')
==>p[notes->online]
gremlin> g.E(knows).properties('notes').drop()
gremlin> g.E(knows)
gremlin>

This next example creates the same set of data, but instead of setting the 'notes' property in the same traversal as the addE step, it creates the property in a separate traversal. Unlike in the example above, dropping the 'notes' property drops the property while leaving the edge intact.

gremlin> person1 = g.addV('person').next()
==>v[{~label=person, community_id=1437137920, member_id=0}]
gremlin> person2 = g.addV('person').next()
==>v[{~label=person, community_id=1317720192, member_id=0}]
gremlin> knows = g.V(person1).addE('knows').to(V(person2)).next()
==>e[{~type=knows, out_vertex={~label=person, community_id=1437137920, member_id=0}, in_vertex={~label=person, community_id=1317720192, member_id=0}, local_id=847ebaf0-a6b8-11e6-aa90-df2b21a156a2}][{~label=person, community_id=1437137920, member_id=0}-knows->{~label=person, community_id=1317720192, member_id=0}]
gremlin> g.E(knows).property('notes', 'online')
==>e[{~type=knows, out_vertex={~label=person, community_id=1437137920, member_id=0}, in_vertex={~label=person, community_id=1317720192, member_id=0}, local_id=847ebaf0-a6b8-11e6-aa90-df2b21a156a2}][{~label=person, community_id=1437137920, member_id=0}-knows->{~label=person, community_id=1317720192, member_id=0}]
gremlin> g.E(knows).properties()
==>p[notes->online]
gremlin> g.E(knows).properties('notes').drop()
gremlin> g.E(knows)
==>e[{~type=knows, out_vertex={~label=person, community_id=1437137920, member_id=0}, in_vertex={~label=person, community_id=1317720192, member_id=0}, local_id=847ebaf0-a6b8-11e6-aa90-df2b21a156a2}][{~label=person, community_id=1437137920, member_id=0}-knows->{~label=person, community_id=1317720192, member_id=0}]
gremlin> g.E(knows).properties()
gremlin> 

Answer 1

Thank you for the feedback Leifur. This appears to be a bug and we've filed an internal JIRA and the engineering team is investigating.