How can SQL retrieve and count nodes two degrees away (friends-of-friends) for a specific node? For example, try:
SELECT COUNT(DISTINCT t2.connection)
FROM network AS t1
JOIN network AS t2 ON t1.connection = t2.member
WHERE t1.member = 'nodeA'
AND t2.connection <> 'nodeA'
AND t2.connection NOT IN (SELECT connection FROM network WHERE member = 'nodeA');
This query is a good starting point for retrieving friends-of-friends while avoiding direct connections, but an important aspect is ensuring that performance remains optimal on larger networks. In my personal experience, relying on self-joins and nested queries can lead to inefficient execution plans if indexes are missing on key fields. Indexing the member and connection columns can significantly enhance performance. Additionally, consider rewriting the query with common table expressions to simplify troubleshooting and readability, especially when expanding to more degrees of separation in complex networks.
i tried a cte approach: first grab direct friens then join again for second-level links. makes things clearer, esp when scaling up. tuning those join filters and indexes is still key if you got a huge network.
hey there, im curious if u ever tried using recursive queries instead? sometimes it offers neat benefits but can be a bit tricky. what u think? any experiance with recusrive methods instead of join chains?
In my experience, an effective alternative approach is to use derived tables to separate out the direct connections from the indirect ones. By first isolating direct relationships in an inline view, subsequent joins to fetch second-level nodes become much clearer. This modular strategy not only simplifies the query structure but also assists in debugging and maintenance. I found that with proper indexing, this method can yield comparable performance benefits while offering easier adjustment of filters and criteria, making it a robust solution for analyzing friends-of-friends networks.