Gremlin query works in TinkerGraph, JanusGraph and Neo4j but not in DSE Graph 6.8.1 - gremlin

I have the following query which works without any issues with TinkerGraph, JanusGraph and Neo4j-Gremlin:
g.V().has('Account','address','0x0').
out('sent').has('eventName','Transfer').as('t1').
out('received_by').has('type','EOA').has('status','Active').as('a2').
out('sent').has('eventName','Transfer').as('t2').
where('t1',eq('t2')).by('address').
where('t1',eq('t2')).by('amount').
out('received_by').has('type','EOA').has('status','Active').as('a3').
select('a3','a2').
by('address').
group().
by('a3').
by('a2').
unfold().
where(select(values).limit(local,2).count(local).is(gte(2).and(lte(1000))))
But with DataStax Graph I get the following error:
java.util.LinkedHashMap cannot be cast to org.apache.tinkerpop.gremlin.structure.Element
I know the issue is after the select but I haven't been able to figure out in which point is really failing. Any ideas would help. Thanks.

DataStax Graph 6.8.1 uses an early release of TinkerPop 3.4.5. That release does not contain the full release feature that allows by(String) to work on a Map. You should be able to re-write your traversal to:
g.V().has('Account','address','0x0').
out('sent').has('eventName','Transfer').as('t1').
out('received_by').has('type','EOA').has('status','Active').as('a2').
out('sent').has('eventName','Transfer').as('t2').
where('t1',eq('t2')).by('address').
where('t1',eq('t2')).by('amount').
out('received_by').has('type','EOA').has('status','Active').as('a3').
select('a3','a2').
by('address').
group().
by(select('a3')).
by(select('a2').fold()).
unfold().
where(select(values).limit(local,2).count(local).is(gte(2).and(lte(1000))))

Related

Need a query to retrieve complete graph

I am trying to retrieve all the node and properties details in parent-child hierarchy.
Nested within each other.
Since I am new with gremlin, graphDB I am having really tough time to get it done.
Please suggest a solution and if you could walk me through it, it will be great.
Following is my structure
And I am trying to keep the response as clean as possible.
I am using cosmosDB and Gremlin.
NET api for this.
I tried the following but it gave me response in key value,
g.V("some_id").repeat(out()).emit().tree().path()
g.V("some_id").emit().repeat(both().simplePath()).dedup()
please any kind of suggestion would be great.
I"m not sure what format you want your result, but use of path(), tree() or subgraph() would typically give you the graph structure. Since you are using CosmosDB, you're only options are path() and tree() as subgraph() does not appear to be supported.
Using this sample graph as a simple tree:
g.addV().property(id, '1').as('1').
addV().property(id, '2a').as('2a').
addV().property(id, '2b').as('2b').
addV().property(id, '3a').as('3a').
addV().property(id, '4a').as('4a').
addE('child').from('1').to('2a').
addE('child').from('1').to('2b').
addE('child').from('2a').to('3a').
addE('child').from('3a').to('4a')
you can see the effect of path() which basically gathers the contents of each step Gremlin took:
gremlin> g.V('1').repeat(out()).emit().path()
==>[v[1],v[2a]]
==>[v[1],v[2b]]
==>[v[1],v[2a],v[3a]]
==>[v[1],v[2a],v[3a],v[4a]]
Since I used out() we don't see the edges, but that is easily remedied by adding making a small adjustment to directly consume edges into the path history:
gremlin> g.V('1').repeat(outE().inV()).emit().path()
==>[v[1],e[0][1-child->2a],v[2a]]
==>[v[1],e[1][1-child->2b],v[2b]]
==>[v[1],e[0][1-child->2a],v[2a],e[2][2a-child->3a],v[3a]]
==>[v[1],e[0][1-child->2a],v[2a],e[2][2a-child->3a],v[3a],e[3][3a-child->4a],v[4a]]
Taken together with duplication removed on your application side you have a complete graph with path().
Replacing path() with tree() will essentially do that deduplication by maintaining the tree structure of the path history:
gremlin> g.V('1').repeat(out()).emit().tree()
==>[v[1]:[v[2b]:[],v[2a]:[v[3a]:[v[4a]:[]]]]]
gremlin> g.V('1').repeat(outE().inV()).emit().tree()
==>[v[1]:[e[0][1-child->2a]:[v[2a]:[e[2][2a-child->3a]:[v[3a]:[e[3][3a-child->4a]:[v[4a]:[]]]]]],e[1][1-child->2b]:[v[2b]:[]]]]
The Tree is just represented as a Map where each key represents a like a root and value is another Tree (i.e. the branches from it). It is perhaps better visualized this way:
gremlin> g.V('1').repeat(out()).emit().tree().unfold()
==>v[1]={v[2b]={}, v[2a]={v[3a]={v[4a]={}}}}
gremlin> g.V('1').repeat(out()).emit().tree().unfold().next().value
==>v[2b]={}
==>v[2a]={v[3a]={v[4a]={}}}
If neither of these structures are suitable and subgraph() is not available you can technically just capture and return the edges you traverse as the low level elements of your subgraph as described in this blog post.
Given the comments on this answer I also present the following option which used group():
gremlin> g.V('1').emit().
......1> repeat(outE().group('a').by(outV()).by(inV().fold()).inV()).cap('a').unfold()
==>v[1]=[v[2a], v[2b]]
==>v[3a]=[v[4a]]
==>v[2a]=[v[3a]]
It's not exactly a "tree" but if you know the root (in this case v[1]) you can find its key in the Map. The values are the children. You can then look up each of those keys in the Map to find if they have children and so on. For example, we can lookup v[2b] and find that it has no children while looking up [v2a] reveals a single child of [v3a]. Gremlin can be pretty flexible in getting answers if you can be sorta flexible in how you deal with the results.

Concatenate Gremlin GraphTraversal result with string

In this very simple example I am trying to add a new vertex which should be labeled like an existing vertex but with some prefix attached:
g.V(1).addV('prefix_' + label()).valueMap(true)
What am I missing here? It's clearly not a String, but how would I serialize that?
gremlin> g.V(1).label()
==>Person
gremlin> g.V(1).constant(label())
==>[LabelStep]
Gremlin today does not provide a built in string concatenation function. It would be nice if it did. That means your best alternative today is to use an in line closure/lambda. Here is an example using TinkerGraph and the air-routes graph.
gremlin> g.V(3).map {"prefix_" + it.get().label}.as('a').addV(select('a'))
==>v[60867]
gremlin> g.V(60867).label()
==>prefix_airport
Note that not all graph databases allow closures so this cannot be assumed to work universally on any TinkerPop enabled Graph DB backend.

Gremlin/Neptune: sort edges by vertex property

Using the gremlin console connected remotely to a Neptune DB instance, I am grabbing all edges with a specific label and want to sort them by the id of the out vertex. I'm getting this error: "code":"UnsupportedOperationException","detailedMessage":"com.amazon.neptune.storage.volcano.ast.CutoffNode cannot be cast to com.amazon.neptune.storage.volcano.ast.AbstractGroupNode".
Sample data:
g.addV('user').property(id,'1').
addV('content').property(id,'2').
addE('history').property('val',9).from(g.V('1')).to(g.V('2'))
Queries and outputs:
g.E().hasLabel('history').order().by('val')
==>e[3][1-history>2]
g.E().hasLabel('history').outV().id()
==>1
g.E().hasLabel('history').order().by(outV().id())
{"requestId":<stuff>,"code":"UnsupportedOperationException","detailedMessage":
"com.amazon.neptune.storage.volcano.ast.CutoffNode cannot be cast to
com.amazon.neptune.storage.volcano.ast.AbstractGroupNode"}
I expect the result of that last one to be the same as the first. I've tried the same traversal in a TinkerGraph and didn't get an error, so judging by that and the message it's specifically a Neptune problem. Googling hasn't brought up anything.
Is there a traversal that will do what I'm looking for? What am I doing wrong?
I will look into why the error is being thrown but in the near term I think this workaround should work. Please let me know if it does not.
g.E().order().by(identity().outV().id())
Cheers,
Kelvin

Have Gremlin-console show all the methods available for a specific object?

In gremlin-console, is there a way to show all the methods available for a specific object?
For example, In gremlin-console if I type g.V().hasLabel("person") and I want to see what methods I can chain/call for the object returned by g.V().hasLabel("person"). How do you do that?
The answer is to use the <Tab> key.
gremlin> "test".c
capitalize() center( charAt( chars() codePointAt( codePointBefore( codePointCount( codePoints() collectReplacements( compareTo(
compareToIgnoreCase( concat( contains( contentEquals( count(
However, I'm finding that it is not working for something like g.V().o which I'd hoped would have shown out(). Apparently, the groovy shell (which is what the Gremlin Console is based on) doesn't seem to want to do the auto-complete on a fluent API. It seems to only work on the first object on which you are calling the method:
gremlin> g.
E( V( addV( addV() close() inject( tx() withBindings( withBulk(
withComputer( withComputer() withPath() withRemote( withSack( withSideEffect( withStrategies( withoutStrategies( anonymousTraversalClass
bytecode graph strategies
gremlin> x = g.V();[]
gremlin> x.o
option( optional( or( order( order() otherV() out( outE( outV()
gremlin> x.o
That stinks...that's not really a TinkerPop issue - we rely on the groovysh for that functionality. Not much we can do there I don't think....
Of course, you are using DSE Graph which means you have access to DataStax Studio which not only has the auto-complete that you're looking for but also schema support (and more!). I'd suggest that you switch to that.

Paging or Using Skip in Azure Cosmos

Has anyone been able to determine the equivalent of Gremlin Skip in Azure Cosmos? It's not listed on Microsoft's documentation and I was thinking it's just outdated. I did try doing a query such as g.V().hasLabel('the_label').has('the_property', eq('the_value')).skip(some_number) and it errors out as such Unable to find any method 'skip'.
From your link in the Apache TinkerPop documentation:
The skip()-step is analogous to range()-step save that the higher end range is set to -1.
with these examples:
gremlin> g.V().values('age').order().skip(2)
==>32
==>35
gremlin> g.V().values('age').order().range(2, -1)
==>32
==>35

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