Pattern Matching Tutorial
This tutorial shows you how to write and run pattern matching queries.
This tutorial assumes you have finished GSQL 101, and are familiar with the basics of defining a schema, loading data, and how to write basic queries.
What is a graph pattern?
Imagine drawing a line over an image of the graph, starting from a particular vertex and tracing a route across edges and vertices to another vertex.
A graph pattern is exactly that - a traversal trace on the graph schema. In fact, it’s even more open-ended than that, because a graph pattern:
Can be linear (Vertex A to Vertex B)
Can be non-linear (a tree or circle shape)
Can traverse the same vertices multiple times
For example, imagine a simple schema consisting of a Person vertex type and a Friendship edge type. A pattern could be a trace on this simple schema, going from a Person across the Friendship edge and to another Person.
Person - (Friendship) - Person
A pattern could continue on to additional Person vertices beyond the second one:
Person - (Friendship) - Person - (Friendship) - Person
We can use a different notation here,
*2, to express that we interacted with two Friendship edges.
Person - (Friendship*2) - Person
What is pattern matching?
Pattern matching is the process of finding subgraphs in a graph that conform to a given query pattern.
Pattern matching provides a simple, declarative way to write queries to search for multi-hop patterns.
You can write multi-hop patterns in one query block (
SELECT-FROM-WHERE) instead of several individual blocks.
The pattern can be fixed length or variable length (using Kleene stars for repeated hops), which significantly shortens the GSQL query length.
Follow the sequence below to learn how to write pattern matching queries in GSQL.