The intro section is a good summary of why distributed SQL databases (Spanner, roach, Yugabyte, TiDB) haven't taken off in the market in the same way as say distributed data warehouses have (Snowflake, Databricks, FabricDW, Clickhouse, etc.).
I would add a few other things to the list of scaling problems. Some SQL features are hard to scale out (auto_increment/serial columns, unique secondary keys, foreign keys, etc.). Some SQL query operators are hard to scale out for OLTP queries that want low latency and high throughput (DISTINCT, LIMIT/TOP-N, non-collocated joins). I take it SpacetimeDB is a nosql database, so these problems are less important to them?
As to how spacetimedb plans to scale out, I didn't follow it fully. It's hard to take the spacetimedb folks seriously (see: https://strn.cat/posts/spacetime/).
I would add a few other things to the list of scaling problems. Some SQL features are hard to scale out (auto_increment/serial columns, unique secondary keys, foreign keys, etc.). Some SQL query operators are hard to scale out for OLTP queries that want low latency and high throughput (DISTINCT, LIMIT/TOP-N, non-collocated joins). I take it SpacetimeDB is a nosql database, so these problems are less important to them?
As to how spacetimedb plans to scale out, I didn't follow it fully. It's hard to take the spacetimedb folks seriously (see: https://strn.cat/posts/spacetime/).