-- pg_turbovec v2.16.0
--
-- MINOR: IVF coarse centroids are now trained with e-means (Bessa et al.,
-- Meta FAIR, arXiv 2611.09501) instead of classic Lloyd. Faster build (~5x)
-- and higher measured IVF recall@10 on SIFT1M. No SQL-surface change, no
-- wire-format change (MetaPageData::version stays 8), scoring bit-identical.
-- No forced REINDEX.
--
-- Two new GUCs (registered by the library at load time, not by SQL):
--   turbovec.ivf_use_emeans  (bool, default on)  -- off = Lloyd fallback
--   turbovec.ivf_emeans_epochs (int, default 4)  -- e-means epoch budget
--
-- The trainer is a build-time choice: a NEW `WITH (lists = N)` build gets
-- e-means-trained centroids; existing IVF indexes keep their centroids and
-- read fine. REINDEX an IVF index to adopt the new trainer (optional; higher
-- recall). `ALTER EXTENSION pg_turbovec UPDATE TO '2.16.0'` is sufficient.
-- Intentionally empty apart from this comment.