I have a schema that is the souce with an element that is unbounded. I have a similar element on the destination schema that is also unbounded. I'm trying to figure out how in the map I can ignore the first instance in the source map?
Connect the unbounded source record to an 'Iteration' functoid.
Connect the 'Iteration' to a 'Greater Than' functoid. Add a '1' as input paramter.
Connect the result of the 'Greater Than' to the unbounded record in the destination.
Related
The Nebula Graph docs say that "When traversing all vertices of the specified Tag or edge of the specified Edge Type, such as MATCH (v:player) RETURN v LIMIT N, there is no need to create an index, but you need to use LIMIT to limit the number of output results." But when I run the statement in the preceding screenshot, it told me that I did not have a limit number, which I did.
What is the correct way to RETURN v without creating indexes?
I met the same issue before. Actually, when you specify both a tag and an edge for a query simultaneously, you need to create an index for the tag or the edge first.
Create an index for the tag company first and then try to execute it again.
The Gremlin query that I use to get the list of all outgoing vertices (with edge label “has”) from a selected vertex “P1” until it reaches the vertex with specific label “L3” is this:
g.V().has("id”,”P1”).repeat(out(“has”)).until(hasLabel(“L3”)).path().by("id")
As expected, the query above returns me the list of all intermediate nodes between selected vertex and target vertex labeled “L3”.
However, when using the same query (changing the ‘out’ to ‘in’) in opposite direction, i.e., to get the list of all incoming vertices from a selected vertex to the target vertex with specific label, i get a gremlin query error straight away.
Here is the query:
g.V().has("id”,”P3”).repeat(in(“has”)).until(hasLabel(“L1”)).path().by("id")
The error looks like this:
Failure in submitting query:
Error: Script compile error: Missing ')'
I don’t see any missing brackets in the query though and the only change between the queries for incoming or outgoing vertices i made is using ‘in’ instead of ‘out’.
In the official tinkerpop documentation (https://tinkerpop.apache.org/docs/3.2.9/reference/#_traversal_strategies_2), in traversal strategies, I cannot find any example with repeat(in()), only with repeat(out()). Is there a special query or method to get all the incoming vertices from a selected vertex until it reaches the vertex with a specific label?
I'm not sure if this is your problem or not, but I could see where you would get an error because "in" is a reserved word in Groovy so, you have to explicitly spawn it using the anonymous traversal class with: __.in(), therefore:
g.V().has("id","P3").repeat(__.in("has")).until(hasLabel("L1")).path().by("id")
This issue is documented in a number of places in the Reference Documentation, but perhaps you missed it (you referenced a fairly old version of the documentation as well) - described here in a NOTE in the Vertex Steps for example.
I'm attempting to build a recommendation engine for a library system.
This is my db schema:
My starting point is a LoanerCard. The flow is then supposed to look like this: Get all copies -> get the material -> get all copies of the material (including the original) -> get LoanerCard from copy -> get all loaned copies -> return the material name of the copies + an aggregated count to indicate the strength of the recommendation.
My best attempt so far has resulted in this query:
MATCH (L:LoanerCard {Barcode:"10007"})-[:LOANED]->(myLoans)-[:COPY_OF]-
(masterMaterial),
(masterMaterial)<-[:COPY_OF]-(allCopies),
(allCopies)<-[:LOANED]-(coLoaners),
(coLoaners)-[r:LOANED]->(theirCopies),
(theirCopies)-[:COPY_OF]-(materials)
RETURN materials.Title as Recommended, count(*) as Strength ORDER BY Strength DESC
My issue here is that when I traverse the graph it doesn't include the original copy and the adjacent LoanerCards of that so essentially it only traverses the area circled in red and never reaches LoanerCard 10817 and 10558
How can I design my query so it includes these?
A MATCH clause automatically filters out duplicate relationships. Therefore, in order to traverse the same relationships twice, you need to split your MATCH clause in two.
Try this:
MATCH (:LoanerCard {Barcode:"10007"})-[:LOANED]->()-[:COPY_OF]-(masterMaterial)
MATCH (masterMaterial)<-[:COPY_OF]-()<-[:LOANED]-()-[:LOANED]->()-[:COPY_OF]-(materials)
RETURN materials.Title as Recommended, count(*) as Strength ORDER BY Strength DESC
So I have a graph that looks like this(starting from the rightmost side) with relationships that have a unique number attribute called Isnad. I want to write a query to get the length of every Isnad from the start node to the end node but I can't figure it out. I don't know how to traverse every path for every Isnad separately. Any help?
I don't know if it is the most elegant and solution, but I think it works. First, I'm getting all unique Isnad values of relationships outgoing from the rightmost side node using an identifier. Then I'm using a variable-length pattern matching where all relationships have the same value for Isnad property. Then the Isnad value and the path length are returned.
match ({id:'unique-identifier-of-rightmost-side-node'})-[r]->()
with distinct r.Isnad as Isnad
match p = ()-[*{Isnad : Isnad}]->()
return Isnad, length(p) as Length
Just out of curiosity, looks like a distinct field must be placed ahead of any other fields, am I wrong?
See this example in SQLite,
sqlite> select ip, distinct code from parser; # syntax error?
Error: near "distinct": syntax error
sqlite> select distinct code, ip from parser; # works
Why is that? Do I really have a syntax error?
There is no such thing as a "distinct field".
distinct applies to all fields in the query and therefore must appear immediately after select.
In other words, select distinct code, ip is really
select distinct
code,
ip
rather than
select
distinct code,
ip
It selects all distinct pairs of (code, ip). Thus the result set could include repeated values of code (each with a different value of ip).
It is not possible to apply distinct to a single field in the way you're trying to (group by might be a useful alternative, but we need to understand what it is exactly that you're trying to achieve).