Serious answer: limiting to just Open Source: JanusGraph, DGraph, Apache AGE, HugeGraph, MemGraph and ArcadeDB all meet that criteria.
replyWhat is open source and what is a graph database are both hotly debated topics.
replyAuthor of ArcadeDB critiques many nominally open source licenses here:
https://www.linkedin.com/posts/garulli_why-arcadedb-will-nev...
What is a graph database is also relevant:
- Does it need index free adjacency?
- Does it need to implement compressed sparse rows?
- Does it need to implement ACID?
- Does translating Cypher to SQL count as a graph database?That's a difficult question and I would like to avoid giving a direct answer (because I co-lead a nonprofit benchmarking graph databases) but even knowing what you need for a graph database can be a tricky decision. See my FOSDEM 2025 talk, where I tried to make sense of the field:
replyhttps://archive.fosdem.org/2025/schedule/event/fosdem-2025-5...
What people perceive as "Facebook production graph" is not just TAO. There is an ecosystem around it and I wrote one piece of it.
replyFull history here: https://www.linkedin.com/pulse/brief-history-graphs-facebook...
Yeah: Postgres, etc.
replyWhen you actually need to run graph algorithms against your relational data, you export the subset of that data into something like Grafeo (embedded mode is a big plus here) and run your analysis.
That importing is expensive and prevents you from handling billion scale graphs.
replyIt's possible to run cypher against duckdb (soon postgres as well via duckdb's postgres extension) without having to import anything. That's a game changer when everything is in the same process.