Why DuckDB 2.0 is faster

What happened

DuckDB 2.0 alpha vs 1.5.5 on one laptop: recursive CTEs up to 90x, VARIANT 6x faster than JSON text, async I/O 2.4x on S3. What changes, and how to model data to get the speedup. | Reading time: 15 min read

Summary assembled by rule from the sources below

Sources