Realtime full MSSQL database mirroring into DuckDb to do a complex reporting. Everything is in-process. DuckDb database mapped to temp storage and recreated on app restart. Still order of magnitude faster then doing a direct query over MSSQL Server (2ms vs 40+ seconds on same query).

Some devs in team still cannot believe that there is no cheating, that it's possibe, that some 60Mb DB can do queries faster then MSSQL Server with just around 250Mb+ of memory overhead.

(.Net 10 + DuckDB.NET package)