Parameterized Flows follow Brightway’s ParameterizedExchange index

The Parameters page Parameterized Flows table, recalculation, and Monte Carlo all use Brightway’s ParameterizedExchange index (activity-parameter group), not a scan of formula-bearing flows. A bwutils helper rebuilds that index for the written database when the database is small or already has parameters. Small means at most 1,000 outgoing flows. Skip databases above that cap that have no database/activity parameters; otherwise delete that database’s index rows, index every process that has a formula-bearing flow (dummy activity parameter if needed), then recalculate those groups. A database over the cap that already has parameters still gets a full pass. Single-flow formula edits stay on ExchangeModify. No one-shot backfill of existing projects.

Invocation: rebuild runs from ABSignals on Brightway on_database_write (while the writing thread still has SQLite available). Brightway Database.write sends that signal only when projects.dataset.is_sourced is true (default false), or when the caller passes signal=True. Excel import extra-sends that signal after bw2io writes with signals off. Database duplicate and BW25 migration pass signal=True so the same handler rebuilds the copy. Silent writes leave the index stale by design. Metadata store reload is deferred separately under SafeBWConnection (ADR-0013) and does not delay this rebuild.

Considered Options

  • Scan formula-bearing flows on every Parameters-page sync (shows flows that will not recalculate).
  • Fill the index only on Excel import via bw2io activate_parameters (misses database-parameter-only processes and other writes).
  • One-shot backfill of open projects (rejected: user rebuilds those by rewrite).
  • Rebuild as a write “settler” with deferred blinker delivery (rejected: too complex; MDS deferral alone is enough).