DuckDB is great but it’s barely OLAP right? A key part of OLAP is “online”. Since the writer process blocks any other processes from doing reads, calling it OLAP is a stretch I think.
Isn't the Online part here about getting results immediately after query, as opposed to overnight batch reports? So if you don't completely overwhelm DuckDB with writes, it still qualifies. The quality you're describing is something like "realtime analytics", and is a whole another category: Clickhouse doesn't qualify (batching updates, merging etc. — but it's clearly OLAP), Druid does.
For certain definition of realtime, certainly (as would any system with bounded ingestion latency), but it’s not low-latency streaming realtime. Tens of seconds or more can pass before new data becomes visible in queries in normal operation. There’s batching, there’s merging, and its overall architecture prioritizes throughput over latency.
