Stephen Mallette created TINKERPOP-2608:
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Summary: Enhance sample().by() semantics when by produces a null
Key: TINKERPOP-2608
URL: https://issues.apache.org/jira/browse/TINKERPOP-2608
Project: TinkerPop
Issue Type: Improvement
Components: process
Affects Versions: 3.5.1
Reporter: Stephen Mallette
We currently get a NPE for this:
{code}
gremlin> g.V().sample(1).by("age")
java.lang.NullPointerException
Type ':help' or ':h' for help.
Display stack trace? [yN]
{code}
Since {{sample()}} is a filter, it seems intuitive that it could remove
traversers that don't resolve in the {{by()}}. Of course, that changes the
current semantics when the sample size is greater than or equal to the size of
the traverser set:
{code}
gremlin> g.V().sample(6).by("age")
==>v[1]
==>v[2]
==>v[3]
==>v[4]
==>v[5]
==>v[6]
{code}
As an aside, we might also improve this error messaging:
{code}
gremlin> g.V().sample(1).by("name")
class java.lang.String cannot be cast to class java.lang.Number
(java.lang.String and java.lang.Number are in module java.base of loader
'bootstrap')
Type ':help' or ':h' for help.
Display stack trace? [yN]
{code}
As this would change Gremlin semantics a bit, it should target the next
breaking version.
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