Graphs in the Real World - Graph Databases - page 108

Figure 5-2. Pattern to find colleagues who share a user's interests
The query works as follows:
• START looks up the subject of the query in the user index, and assigns the result to
the subject identifier.
• MATCH then matches this person with people who work for the same company, and
who share one or more of their interests. If the subject of the query is Sarah, who
works for Acme, then in the case of Ben, MATCH will match twice: ('Acme')<-
[:WORKS_FOR]-('Ben')-[:INTERESTED_IN]->('graphs') and ('Acme')<-
[:WORKS_FOR]-('Ben')-[:INTERESTED_IN]->('REST') . In the case of Charlie, it
will match once: ('Acme')<-[:WORKS_FOR]-('Charlie')-[:INTERESTED_IN]-
>('graphs') .
• RETURN creates a projection of the matched data: for each matched colleague, we
extract their name, count the number of interests they have in common with the
subject of the query (aliasing this result as score ), and, using collect , create a
comma-separated list of these mutual interests. Where a person has multiple
matches, as does Ben in our example, count and collect aggregate their matches
into a single row in the returned results (in fact, both count and collect can per‐
form this aggregating function independently of one another).
• Finally, we order the results based on each colleague's score , highest first.