-- pg_turbovec v2.15.1
--
-- PATCH: fixes a .tvim duplicate-id corruption that a CANCELLED VACUUM
-- could leave in a FLAT index (operator report 2026-11-13). No SQL-surface
-- change, no GUC change, no wire-format change (MetaPageData::version stays
-- 8), scoring bit-identical.
--
-- The flat VACUUM swap-remove moved each live tail slot into a dead hole with
-- separate per-slot GenericXLog records and lowered n_vectors only after the
-- loop. A cancel (routinely, an autovacuum lock-conflict cancellation) or a
-- crash between a move and that final shrink left the moved row counted at
-- both its new slot and its old tail slot -- "id N appears in more than one
-- slot", which then blocked every INSERT. The swap-remove now lowers
-- n_vectors in the SAME GenericXLog record as each move, so every durable
-- image is a clean bijection; an interrupt or crash leaves a smaller but
-- correct table. IVF/graph/1-bit-BQ indexes were never affected (they use
-- the tombstone path, no slot moves).
--
-- No REINDEX required by the upgrade. An index ALREADY corrupted by this bug
-- is repaired by a plain `REINDEX INDEX <name>;` (it does not recur once this
-- release is installed). `ALTER EXTENSION pg_turbovec UPDATE TO '2.15.1';` is
-- sufficient. Intentionally empty apart from this comment.