[TINKERPOP-1638] count() is optimized away in where()

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 3.2.1
• Fix Version/s: 3.3.0, 3.2.5
• Component/s: process
• Assignee: Daniel Kuppitz
• Reporter: Robert Dale
• Created: 23/Feb/17 13:37
• Updated: 27/Feb/17 18:43
• Resolved: 27/Feb/17 18:43

Description

See also gremlin-users discussion

This produces no results:

gremlin> graph = TinkerFactory.createModern()
==>tinkergraph[vertices:6 edges:6]
gremlin> g = graph.traversal()
==>graphtraversalsource[tinkergraph[vertices:6 edges:6], standard]
gremlin> g.V().where( __.in('A').in('B').count().is(eq(0)) )
gremlin> 

In 3.2.0-incubating, it correctly (or atleast expectedly) produces:

==>v[1]
==>v[2]
==>v[3]
==>v[4]
==>v[5]
==>v[6]

Outside of the where() clause, it produces the expected result:

gremlin> g.V().in('A').in('B').count()
==>0

Thus, one could expect it to work inside the where() clause. It appears that some optimization occurs that removes the count step and converts it into a NotStep.

3.2.0-incubating:

gremlin> g.V().where( __.in('A').in('B').count().is(eq(0)) ).explain()
==>Traversal Explanation
================================================================================================================================================================================================
Original Traversal                 [GraphStep(vertex,[]), TraversalFilterStep([VertexStep(IN,[A],vertex), VertexStep(IN,[B],vertex), CountGlobalStep, IsStep(eq(0))])]

ConnectiveStrategy           [D]   [GraphStep(vertex,[]), TraversalFilterStep([VertexStep(IN,[A],vertex), VertexStep(IN,[B],vertex), CountGlobalStep, IsStep(eq(0))])]
IdentityRemovalStrategy      [O]   [GraphStep(vertex,[]), TraversalFilterStep([VertexStep(IN,[A],vertex), VertexStep(IN,[B],vertex), CountGlobalStep, IsStep(eq(0))])]
IncidentToAdjacentStrategy   [O]   [GraphStep(vertex,[]), TraversalFilterStep([VertexStep(IN,[A],vertex), VertexStep(IN,[B],vertex), CountGlobalStep, IsStep(eq(0))])]
AdjacentToIncidentStrategy   [O]   [GraphStep(vertex,[]), TraversalFilterStep([VertexStep(IN,[A],vertex), VertexStep(IN,[B],edge), CountGlobalStep, IsStep(eq(0))])]
FilterRankingStrategy        [O]   [GraphStep(vertex,[]), TraversalFilterStep([VertexStep(IN,[A],vertex), VertexStep(IN,[B],edge), CountGlobalStep, IsStep(eq(0))])]
MatchPredicateStrategy       [O]   [GraphStep(vertex,[]), TraversalFilterStep([VertexStep(IN,[A],vertex), VertexStep(IN,[B],edge), CountGlobalStep, IsStep(eq(0))])]
RangeByIsCountStrategy       [O]   [GraphStep(vertex,[]), TraversalFilterStep([VertexStep(IN,[A],vertex), VertexStep(IN,[B],edge), RangeGlobalStep(0,1), CountGlobalStep, IsStep(eq(0))])]
TinkerGraphStepStrategy      [P]   [TinkerGraphStep(vertex,[]), TraversalFilterStep([VertexStep(IN,[A],vertex), VertexStep(IN,[B],edge), RangeGlobalStep(0,1), CountGlobalStep, IsStep(eq(0))])]
ProfileStrategy              [F]   [TinkerGraphStep(vertex,[]), TraversalFilterStep([VertexStep(IN,[A],vertex), VertexStep(IN,[B],edge), RangeGlobalStep(0,1), CountGlobalStep, IsStep(eq(0))])]
StandardVerificationStrategy [V]   [TinkerGraphStep(vertex,[]), TraversalFilterStep([VertexStep(IN,[A],vertex), VertexStep(IN,[B],edge), RangeGlobalStep(0,1), CountGlobalStep, IsStep(eq(0))])]

Final Traversal                    [TinkerGraphStep(vertex,[]), TraversalFilterStep([VertexStep(IN,[A],vertex), VertexStep(IN,[B],edge), RangeGlobalStep(0,1), CountGlobalStep, IsStep(eq(0))])]

3.2.4:

gremlin> g.V().where( __.in('A').in('B').count().is(eq(0)) ).explain()
==>Traversal Explanation
======================================================================================================================================================================
Original Traversal                 [GraphStep(vertex,[]), TraversalFilterStep([VertexStep(IN,[A],vertex), VertexStep(IN,[B],vertex), CountGlobalStep, IsStep(eq(0))])]

ConnectiveStrategy           [D]   [GraphStep(vertex,[]), TraversalFilterStep([VertexStep(IN,[A],vertex), VertexStep(IN,[B],vertex), CountGlobalStep, IsStep(eq(0))])]
MatchPredicateStrategy       [O]   [GraphStep(vertex,[]), TraversalFilterStep([VertexStep(IN,[A],vertex), VertexStep(IN,[B],vertex), CountGlobalStep, IsStep(eq(0))])]
FilterRankingStrategy        [O]   [GraphStep(vertex,[]), TraversalFilterStep([VertexStep(IN,[A],vertex), VertexStep(IN,[B],vertex), CountGlobalStep, IsStep(eq(0))])]
InlineFilterStrategy         [O]   [GraphStep(vertex,[]), TraversalFilterStep([VertexStep(IN,[A],vertex), VertexStep(IN,[B],vertex), CountGlobalStep, IsStep(eq(0))])]
RepeatUnrollStrategy         [O]   [GraphStep(vertex,[]), TraversalFilterStep([VertexStep(IN,[A],vertex), VertexStep(IN,[B],vertex), CountGlobalStep, IsStep(eq(0))])]
PathRetractionStrategy       [O]   [GraphStep(vertex,[]), TraversalFilterStep([VertexStep(IN,[A],vertex), VertexStep(IN,[B],vertex), CountGlobalStep, IsStep(eq(0))])]
RangeByIsCountStrategy       [O]   [GraphStep(vertex,[]), TraversalFilterStep([VertexStep(IN,[A],vertex), NotStep([VertexStep(IN,[B],vertex)])])]
IncidentToAdjacentStrategy   [O]   [GraphStep(vertex,[]), TraversalFilterStep([VertexStep(IN,[A],vertex), NotStep([VertexStep(IN,[B],vertex)])])]
AdjacentToIncidentStrategy   [O]   [GraphStep(vertex,[]), TraversalFilterStep([VertexStep(IN,[A],vertex), NotStep([VertexStep(IN,[B],edge)])])]
LazyBarrierStrategy          [O]   [GraphStep(vertex,[]), TraversalFilterStep([VertexStep(IN,[A],vertex), NotStep([VertexStep(IN,[B],edge)])])]
TinkerGraphCountStrategy     [P]   [GraphStep(vertex,[]), TraversalFilterStep([VertexStep(IN,[A],vertex), NotStep([VertexStep(IN,[B],edge)])])]
TinkerGraphStepStrategy      [P]   [TinkerGraphStep(vertex,[]), TraversalFilterStep([VertexStep(IN,[A],vertex), NotStep([VertexStep(IN,[B],edge)])])]
ProfileStrategy              [F]   [TinkerGraphStep(vertex,[]), TraversalFilterStep([VertexStep(IN,[A],vertex), NotStep([VertexStep(IN,[B],edge)])])]
StandardVerificationStrategy [V]   [TinkerGraphStep(vertex,[]), TraversalFilterStep([VertexStep(IN,[A],vertex), NotStep([VertexStep(IN,[B],edge)])])]

Final Traversal                    [TinkerGraphStep(vertex,[]), TraversalFilterStep([VertexStep(IN,[A],vertex), NotStep([VertexStep(IN,[B],edge)])])]

Issue Links

• is related to: TINKERPOP-1312 .count().is(0) is not properly optimized
• links to: GitHub Pull Request #563