I am using CREATE GRAPH to create a new graph in sparql. Which gives me success update succeeded. But when i query for all the graphs i cant find it. I am using SELECT and Union to query. I am using Fuseki server.
If you have created the graph but have not yet added any data to it, the query pattern GRAPH ?g {?s ?p ?o} won't match the graph, because ?s ?p ?o can not be bound to anything.
The triplestore you are accessing via Fuseki server presumably does not really support the notion of an 'empty graph' (most triplestores don't, although technically it's allowed by the SPARQL standard). The CREATE operation returns true but effectively does nothing. Only when you start actually adding data to the graph is it really created.
Related
On an Azure cosmosDB gremlin instance,
I have 2 vertices A and B linked by and edge E.
Both vertices has a 'name' property.
I'd like to run a query which will take A's name and put it in B
when I run
g.V("AId").as("a").oute().inv().hasLabel('B').property("name",select('a').values('name'))
I get the following error :
GraphRuntimeException ExceptionMessage : Gremlin Query Execution Error: Cannot create ValueField on non-primitive type GraphTraversal.
It looks like the select operator is not correctly used.
Thank you for your help
EDITED based on discussion in comments
You have oute and inv in lower case. In general, the steps use camelCase naming, such as outE and inV (outside of specific GLVs), but in the comments it was mentioned that CosmosDB will accept all lower case step names. Assuming therefore, that is not the issue here, the query as written looks fine in terms of generic Gremlin. The example below was run using TinkerGraph, and uses the same select mechanism to pick the property value.
gremlin> g.V(3).as("a").outE().inV().has('code','LHR').property("name",select('a').values('city'))
==>v[49]
gremlin> g.V(49).values('name')
==>Austin
What you are observing may be specific to CosmosDB and it's probably worth contacting their support folks to double check.
I'm trying to execute an OLAP traversal on a query that needs to check if a vertex has a neighbour of certain type.
i keep getting
Local traversals may not traverse past the local star-graph on GraphComputer
my query looks something like:
g.V().hasLabel('label1').
where(_.out().hasLable('label2'))
I'm using the TraversalVertexProgram.
needless to say, when running the same query in oltp mode there is no problem
is there a way to execute such logic?
That is limitation of TinkerPop OLAP GraphComputer. It operate on 'star-graph' objects. The vertex and connected edges only. It uses message passing engine inside. So you have to rewrite you query.
Option 1: start from label2 and go t label1. This should return the same result
g.V().hasLabel('label2').in().hasLabel('label1')
Option2: try to use unique edge labels and check edge label instead
g.V().hasLabel('label1').where(_.outE('label1_label2'))
How do I write a parameterised gremlin query to add a vertex with many number of properties. I want to parameterise the property in such a way that.. I should be able to pass the properties in a Map and the query to read and insert all those into the vertex. Is this possible at all?
It is only possible with a script where you construct the traversal on the remote side and, then, only possible for graph systems that support scripts in that way (e.g. wouldn't work on CosmosDB). You would just send your script as the following where m is your Map:
t = g.addV()
m.each{k,v -> t= t.property(k,v)]
t
I am trying to perform queries using the OR operator as following:
MapReduceResult result = riakClient.
mapReduce("some_bucket", "Name:c1 OR c2").
addMapPhase(new NamedJSFunction("Riak.mapValuesJson"), true).
execute();
I only get the 1st object in the query (where name='c1').
If I change the order of the query (i.e. Name:c2 OR c1) again I get only the first object in query (where name='c2').
is the OR operator (and other query operators) supported in the java client?
I got this answer from Basho engeneer, Sean C.:
You either need to group the terms or qualify both of them. Without a field identifier, the search query assumes that the default field is being searched. You can determine how the query will be interpreted by using the 'search-cmd explain' command. Here's two alternate ways to express your query:
Name:c1 OR Name:c2
Name:(c1 OR c2)
both options worked for me!
Is there a way to determine if a MATCH query sent to an fts3 table in sqlite is valid? Currently, I don't find out if the expression is invalid until I try to run it, which makes it a little tricky. I'd like to report to the user that the syntax is invalid before even trying to run it.
I'm using sqlite with the C api.
Additionally, doing a search with the expression "NOT " will fail with a "SQLlite logic/database error". Googling seems to indicate that such a query is invalid. Is there a correct syntax to do the operation? I'm essentially trying to find entries that do NOT contain that term. Or do I have to drop back down to using LIKE and do a sequential scan and not use FTS?
Looks like the simplest way right now is to create a separate FTS table with no rows, and execute the query against it. It will be immediate since there's no data in the table, and will report and error if the query syntax is incorrect.