The ones built on Cassandra do this using Spark and neo4j has a built in engine (Gremlin). Any examples of how you map graph queries to relational table structures ? Especially the ones that need traversal
Will put together a follow-up with some more information, but in summary: * yeah, no built-ins for graph operations in Spanner other than relational SQL for standard joins * the key thing that make this work are the ability to easily construct global indexes that aren't sharded by the primary key and reasonably fast joins between them * it's also helpful that Spanner does a reasonable job of parallelizing queries (e.g. a lot of times we'll get a 15x increase in speed vs. a sequential plan) * we then do the fan-out across the graph in our Java Spanner client - each distributed SQL index read takes ~10 ms so we can do multiple round trips of graph traversal in the client
But the question still stands - how does the query engine here work ? at the end of the day, its still a relational system.