[TINKERPOP-2906] Query using coalesce adding the same vertex twice

• Type: Bug
• Status: Closed
• Priority: Critical
• Resolution: Not A Bug
• Affects Version/s: 3.6.0, 3.6.2
• Component/s: process
• Assignee: Unassigned
• Reporter: Kelvin Lawrence
• Created: 14/Mar/23 18:54
• Updated: 03/Apr/23 19:22
• Resolved: 03/Apr/23 19:22

Description

While looking into a question on Stack Overflow about selectively adding a vertex based on a set of values in a list, I think I may have run into an odd issue. Note that this can also be solved using mergeV, but that notwithstanding, the behavior below seems odd. It can be reproduced just using TinkerGraph and the Gremlin Console. Everything works as expected until the RHS of the coalesce() step is an addV() step.

 

gremlin> g.addV('Person').property('name','Sam')
==>v[16]gremlin> g
==>graphtraversalsource[tinkergraph[vertices:1 edges:0], standard]gremlin> g.inject(['Sam','Peter','Frank']).
......1> unfold().as('find').
......2> V().as('p').
......3> coalesce(
......4> where(eq('p')).
......5> by(select('find')).
......6> by('name'),constant(1))
==>v[16]
==>1
==>1gremlin> g.inject(['Sam','Peter','Frank']).
......1> unfold().as('find').
......2> V().as('p').
......3> coalesce(
......4> where(eq('p')).
......5> by(select('find')).
......6> by('name'),select('find'))
==>v[16]
==>Peter
==>Frankgremlin> g.inject(['Sam','Peter','Frank']).
......1> unfold().as('find').
......2> V().as('p').
......3> coalesce(
......4> where(eq('p')).
......5> by(select('find')).
......6> by('name'),addV('Person').property('name',select('find'))
......7> )
==>v[16]
==>v[18]
==>v[20]
==>v[22]gremlin> g.V().valueMap(true)
==>[id:16,label:Person,name:[Sam]]
==>[id:18,label:Person,name:[Peter]]
==>[id:20,label:Person,name:[Frank]]
==>[id:22,label:Person,name:[Frank]]
 
gremlin> g.V().drop()gremlin> g.addV('Person').property('name','Sam')
==>v[24]gremlin> g.inject(['Sam','Peter','Frank']).
......1> unfold().as('find').
......2> V().as('p').
......3> coalesce(
......4> where(eq('p')).
......5> by(select('find')).
......6> by('name'),
......7> addV('Person').property('name',select('find'))).profile()
==>Traversal Metrics
Step Count Traversers Time (ms) % Dur
=============================================================================================================
InjectStep([[Sam, Peter, Frank]]) 1 1 0.043 4.19
UnfoldStep@[find] 3 3 0.083 8.00
TinkerGraphStep(vertex,[])@[p] 4 4 0.155 14.91
CoalesceStep([[WherePredicateStep(null,eq(p),[[... 4 4 0.761 72.89
WherePredicateStep(null,eq(p),[[SelectOneStep... 1 1 0.181
SelectOneStep(last,find,null) 4 4 0.057
AddVertexStep({name=[[SelectOneStep(last,find... 3 3 0.246
SelectOneStep(last,find,null) 3 3 0.025
>TOTAL - - 1.044 -
gremlin> g.inject(['Sam','Peter','Frank']).
......1> unfold().as('find').V().profile()
==>Traversal Metrics
Step Count Traversers Time (ms) % Dur
=============================================================================================================
InjectStep([[Sam, Peter, Frank]]) 1 1 0.028 8.93
UnfoldStep@[find] 3 3 0.043 13.97
TinkerGraphStep(vertex,[]) 3 3 0.241 77.10
>TOTAL - - 0.313 -