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From "Graham Wallis (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (ATLAS-1875) Gremlin id is no longer returned for vertices in gremlin query
Date Thu, 15 Jun 2017 10:09:00 GMT

    [ https://issues.apache.org/jira/browse/ATLAS-1875?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16050270#comment-16050270
] 

Graham Wallis commented on ATLAS-1875:
--------------------------------------

Hi Christian

I looked through the code and think that your proposed change would work. I have not tried
it though; I would try to create a patch and test it but I don't know how to pull in the 0.7
or 0.8 version to build - I always build off the current master.

I noticed that, as you commented, in the "V2" API (which I assume to be AtlasDiscoveryService
implemented by EntityDiscoveryService) there is no ability to search using gremlin directly.
I don't know what the plan is for the "V1" API (which I assume to be the DiscoveryService
implemented by GraphBackedDiscoveryService). Is that being removed at some time? If so I imagine
it will raise the priority of sorting out the DSL performance issue in ATLAS-1868. Or is there
a plan to enable gremlin queries in "V2"?

It's not clear from the code what the plan is around "V1" and "V2" and I've not managed to
find anything or anyone to clarify it.



> Gremlin id is no longer returned for vertices in gremlin query
> --------------------------------------------------------------
>
>                 Key: ATLAS-1875
>                 URL: https://issues.apache.org/jira/browse/ATLAS-1875
>             Project: Atlas
>          Issue Type: Bug
>          Components:  atlas-core
>    Affects Versions: trunk, 0.8-incubating
>            Reporter: Christian R
>              Labels: dsl, gremlin
>
> Hi, 
> while investigating a move from atlas 0.7 to 0.8 (HDP 2.5 to HDP2.6) our tests fail on
gremlin queries. It turns out that the returned entities in a gremlin search in 0.8 does not
include the 'id' attribute. 
> I've built commit a0bd93945cd45457bbf34a8cb819d4fa4ba72964 (0.8-rc1) on linux using berkely
and elasticearch to test with. 
> The query 
> :21000/api/atlas/discovery/search/gremlin?g.V.has('__type.name', 'Infrastructure').collect()
> on our 0.7 cluster gives
> {code:json}
> {
> __type.name: "Infrastructure",
> __type.category: "CLASS",
> __type: "typeSystem",
> id: "16640"
> }{code}
> while the same query on my 0.8-rc1 installation gives 
> {code:javascript}
> {
> __type.name: "Infrastructure",
> __version: "1",
> __type.category: "CLASS",
> __type.version: "1.0",
> __modificationTimestamp: "1497448424134",
> __type: "typeSystem",
> __type.options: "null",
> __type.description: "Infrastructure",
> __guid: "77d07283-7622-4305-9c0c-09ac5aee86c8",
> __timestamp: "1497448424134"
> }
> {code}
> Certainly more information, but id is missing. 
> The very poor DSL performance (see  ATLAS-1868) and a need for advanced queries led us
to base our queries on gremlin. This has worked very well so far. We include both edges and
nodes in the result set and use the inVertex, outVertex and label info on the edges to rebuild
our tree on the client side.
> I also see that gremlin has disappeared from version two of the API. Since addE and addV
lets you insert into the graph I can see how exposing a full gremlin endpoint might not be
wanted. 
> As an example of the queries we run that I haven't been able to express in the DSL is

> {noformat}
> query = g.V.has('__guid','xxxx').copySplit(
> 				_().out('track'), 
> 				_().as('x')
> 				.out('functions', 'component')
> 				.loop('x'){true}{true}
> 					.copySplit(
> 						_(),
> 						_().in('part_of'),
> 						_().outE('functions', 'component'),
> 						_().inE('part_of')
> 					)
> 				.exhaustMerge.dedup
> 			)
> 			.exhaustMerge
>             .collect()
> {noformat}
> this might not be a normal usecase. 
> edit to add: 
> I looked at GraphBackedDiscoveryService.java and notice that:
> 0.7:
> {code:java}
> else if (r instanceof TitanVertex) {
>                 Iterable<TitanProperty> ps = ((TitanVertex) r).getProperties();
>                 for (TitanProperty tP : ps) {
>                     String pName = tP.getPropertyKey().getName();
>                     Object pValue = ((TitanVertex) r).getProperty(pName);
>                     if (pValue != null) {
>                         oRow.put(pName, pValue.toString());
>                     }
>                 }
> {code}
> Vs 0.8 code: 
> {code:java}
> else if (value instanceof AtlasVertex) {
>                     AtlasVertex<?,?> vertex = (AtlasVertex<?,?>)value;
>                     for (String key : vertex.getPropertyKeys()) {
>                         Object propertyValue = GraphHelper.getProperty(vertex,  key);
>                         if (propertyValue != null) {
>                             oRow.put(key, propertyValue.toString());
>                         }
>                     }
> {code}
> look very similar. 
> However, 0.8 handles id in edges explicitly while the 0.7 doesn’t treat edges explicitly
at all.
> {code:java}
> else if(value instanceof AtlasEdge) {
>                     AtlasEdge edge = (AtlasEdge) value;
>                     oRow.put("id", edge.getId().toString());
>                     oRow.put("label", edge.getLabel());
>                     oRow.put("inVertex", edge.getInVertex().getId().toString());
>                     oRow.put("outVertex", edge.getOutVertex().getId().toString());
>                     for (String propertyKey : edge.getPropertyKeys()) {
>                         oRow.put(propertyKey, GraphHelper.getProperty(edge, propertyKey).toString());
>                     }
> {code}
> Should a 
>      oRow.put("id", vertex.getId().toString());
> be added to the vertex-case? 



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