[jira] [Commented] (TINKERPOP-2742) IO read may use wrong cardinality for property

["ASF GitHub Bot (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/TINKERPOP-2742?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17554794#comment-17554794 ] 

ASF GitHub Bot commented on TINKERPOP-2742:
-------------------------------------------

spmallette commented on code in PR #1657:
URL: https://github.com/apache/tinkerpop/pull/1657#discussion_r898437742


##########
tinkergraph-gremlin/src/main/java/org/apache/tinkerpop/gremlin/tinkergraph/structure/TinkerGraph.java:
##########
@@ -411,6 +404,15 @@ public boolean willAllowId(final Object id) {
         public VertexProperty.Cardinality getCardinality(final String key) {
             return defaultVertexPropertyCardinality;
         }
+
+        @Override
+        public VertexProperty.Cardinality getCardinality(final String key, final Object... values) {

Review Comment:
   sorry, @li-boxuan i forgot to come back to this. i think your suggestions in (a) and (b) make sense. a documentation update and a warning to the logs. do you have time to make those changes?





> IO read may use wrong cardinality for property
> ----------------------------------------------
>
>                 Key: TINKERPOP-2742
>                 URL: https://issues.apache.org/jira/browse/TINKERPOP-2742
>             Project: TinkerPop
>          Issue Type: Bug
>          Components: io
>            Reporter: Boxuan Li
>            Priority: Major
>
> g.io(...).read() might lose list/set properties. See the example below:
> {noformat}
> gremlin> graph = TinkerGraph.open()
> ==>tinkergraph[vertices:0 edges:0]
> gremlin> g = graph.traversal()
> ==>graphtraversalsource[tinkergraph[vertices:0 edges:0], standard]
> gremlin> v1 = g.addV().property("feature0", "0.0").property("feature0", "1.1").next()
> ==>v[0]
> gremlin> g.V().valueMap()
> ==>[feature0:[0.0,1.1]]
> gremlin> g.io("graph.json").write().iterate()
> gremlin> g.V().drop()
> gremlin> g.io("graph.json").read().iterate()
> gremlin> g.V().valueMap()
> ==>[feature0:[1.1]]{noformat}
> By verifying "graph.json", I am sure the write() step works fine. The problem is with read() step.
> In [https://github.com/apache/tinkerpop/blob/5fdc7d3b5174f73475ca1a48920d5dec614ffc0e/gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/structure/util/Attachable.java#L294-L298,] it relies on the host graph to decide the cardinality for the given property key. In TinkerGraph, `features().vertex().getCardinality(anything)` always returns default cardinality SINGLE (unless otherwise configured), which means all vertex properties are created with SINGLE cardinality, even if the graph file itself contains multiple values for that property, as shown in the above case.
>  
> I presume TinkerGraph is not the only one who suffers from this problem. For example, for JanusGraph, if the default automatic schema maker is enabled, and a property wasn't defined explicitly, then SINGLE cardinality is returned by default. In this case, the loaded graph will be "wrong" in the sense that it turns LIST/SET values into a SINGLE value.



--
This message was sent by Atlassian Jira
(v8.20.7#820007)