> There's a very non-trivial step in deciding that a particular subset and schema of log messages deserves to be in its own columnar data table.

IIUC this is addressed with the ClickHouse JSON type which can promote individual fields in unstructured data into its own column: https://clickhouse.com/blog/a-new-powerful-json-data-type-fo...

Parquet is getting a VARIANT data type which can do the same thing (called "shredding") but in a standards-based way: https://parquet.apache.org/blog/2026/02/27/variant-type-in-a...