Скачать или смотреть How to Write a Query on Gremlin Console to Return Pair Vertices with Parallel Edges

Discover how to translate Cypher queries to Gremlin console, returning pair vertices with parallel edges using practical examples and clear steps.
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Mastering Gremlin: Returning Pair Vertices with Parallel Edges

In the world of graph databases, Gremlin is a powerful tool that allows you to traverse and query graph data. If you're coming from Cypher, you might wonder how to express certain queries in Gremlin, especially when dealing with parallel edges. In this guide, we will walk through how to write a Gremlin query that returns pair vertices with parallel edges, using a well-structured approach.

Understanding the Problem

A typical need arises when you have vertices connected by multiple edges (in this case, friends). If you are looking to translate a Cypher query like:

[[See Video to Reveal this Text or Code Snippet]]

into Gremlin, you need to structure your query to get the desired results efficiently. This involves navigating through outgoing and incoming edges to find cycles that return you to the starting vertex.

Solution Breakdown

We’ll use the air-routes dataset as our main example and break down the solutions into clear steps for easier understanding.

Using cyclicPath Step

One effective method to achieve this is by using the cyclicPath step. Here’s how you can do it:

[[See Video to Reveal this Text or Code Snippet]]

Explanation:

g.V('44'): Starts at vertex 44.

outE(): Traverses outgoing edges to find neighboring vertices.

inV(): Moves to the incoming vertex of the last edge.

The process is repeated to find a cyclic path.

Output: You will get paths that show the vertices and edges, indicating that you have returned to vertex 44 via parallel edges.

Customizing the Output

If you want more readable output or specific information about the airlines and routes, you can tailor the query:

[[See Video to Reveal this Text or Code Snippet]]

What it does:

by('code'): Replaces the vertex information with a readable "code" property.

This will show you the sequence of codes along with the edges traversed.

Retrieving Edge IDs Only

If you only need the edge IDs, modify the query like so:

[[See Video to Reveal this Text or Code Snippet]]

This will give you a simplified output displaying only the codes and the respective edge IDs between the vertices.

Using the where Step

Another approach includes the where step, which allows for more complex filtering in your query. Here’s an example:

[[See Video to Reveal this Text or Code Snippet]]

This construction:

Flags vertex 'a' as your starting point.

Revisits it through parallel edges before returning the path.

Conclusion

Converting your thoughts from Cypher to Gremlin might take some adjustment, but as this article illustrates, it is definitely achievable with the right structure and commands.
Whether it's using cyclicPath or the where step, you now have the tools needed to express complex relationships and retrieve meaningful data from your graph.

If you have more questions about Gremlin or additional topics you’d like to explore, feel free to ask in the comments below! Happy querying!