README.md

experiments/ — measured evidence

Handbook: meta/experiments/ owns this directory's conventions.

One directory per experiment, holding everything it needs: a README.md that says what was measured, when, on what, and which handbook page relies on it, plus whatever the run took — scripts, inputs, recorded output.

This file is what names the contents, so nothing here is an orphan.

• 2026-03-vendor-build-cost/ — churn per vendor commit, ccache hit rate on adjacent commits, archive size; supports operations/ci/per-commit/planning/.
• 2026-07-main-dev-review/ — how much of a series' active range is R-side work rather than vendoring, and what kind; supports branches/invariants/.
• 2026-08-02-lts-drift/ — how far the v1.4 LTS flavor has drifted from its baseline; supports branches/invariants/.
• 2026-08-05-windows-extension-coverage/ — which prebuilt extensions DuckDB's repositories serve R's Windows builds, and whether the MSVC arm64 artifact can be hand-loaded; supports usage/extensions/.
• 2026-08-08-altrep-scan-threads/ — what a scan returned when it reached a registered ALTREP data frame's packed column itself, per thread count and field type, before and after bind started walking into one; supports architecture/glue/threading/.
• 2026-08-08-interrupt-reach/ — which running DuckDB work a Ctrl+C stops in R and in the DuckDB CLI, and what each host does when it stops nothing; supports usage/interactive/.
• 2026-08-08-timezone-grid/ — which zone labels a TIMESTAMP and a TIMESTAMPTZ column, and when an instant changes, across every setting combination; supports usage/timestamps/.
• 2026-08-09-distinct-on-cost/ — what DISTINCT ON would cost against the ROW_NUMBER() plan dbplyr emits for distinct(.keep_all = TRUE), across cardinality, width, LIMIT and thread count; supports usage/integrations/.
• 2026-08-09-distinct-on-override/ — whether a caller can register DISTINCT ON as their own distinct() method, how far into dbplyr that reaches, and what window_order() already states without it; supports usage/integrations/.
• 2026-08-09-dbplyr-version-warning/ — which API reports the version of the dbplyr a session has loaded rather than the one in the library, when a packageEvent() hook fires, and what a warning raised from one can do to the load it interrupts; supports usage/integrations/.
• 2026-08-09-series-carry-scope/ — how many of a buffer's vendor commits have a fix waiting on the base series' -dev, what kind, and how much of the raw difference is not a fix at all; supports operations/vendoring/series-loop/.
• 2026-08-09-windows-fast-path/ — what the published Windows libduckdb exports, and how much of what the glue resolves from the engine is in there; supports build/fast-paths/.
• 2026-08-temp-storage-spill/ — whether larger-than-memory work actually spills, per connection idiom, on duckdb 1.3.2, the current CRAN release, main, and the fix in #2562; supports usage/memory/.
• 2026-08-streaming-tpch-bench/ — wall time and memory of moving a TPC-H result into R, per fetch strategy, on the CRAN build and #2292's streaming build; gathered for plan/PLAN-streaming-thread.md.

Adding one: create the directory, name it for the date and the topic, open its README.md with what and when and on what, and link it from the leaf that relies on it.