-- pg_turbovec v1.7.0 -- Phase W-2: drop packed_codes mid-finalise.
--
-- This file is a *reference mirror*. The authoritative install
-- script is generated by `cargo pgrx schema`.
--
-- v1.7.0 reorders the `ambuild` finalisation writes so the
-- in-memory row-major `packed_codes` Vec and the SIMD-blocked
-- derived layout are never alive simultaneously. The single-call
-- `relfile::write_full_with_prepared` path is split into two
-- phases:
--
--   1. `relfile::write_packed_phase` streams `packed_codes`,
--      `scales`, and `slot_to_id` into relfile pages.
--   2. The IdMapIndex materialises the SIMD-blocked layout and
--      Lloyd-Max codebook via `prepare_eager()`.
--   3. The new `IdMapIndex::take_packed_codes()` (turbovec 0.7.0)
--      swaps the row-major Vec out and shrink_to_fits it for
--      drop. The blocked OnceLock survives because it's already
--      populated.
--   4. `relfile::write_blocked_phase_and_meta` streams the
--      blocked + rotation chains and stamps the meta page LAST
--      (matching the standard PG hash/gist AM "meta page is the
--      atomic-complete signal" pattern).
--
-- Memory profile at 10M x 1536-d x 4-bit:
--   pre-W (v1.5.x):  121 GiB peak RSS
--   post-W (v1.6.x): 22.5 GiB peak RSS
--   post-W-2 (v1.7): ~15 GiB peak RSS  <-- this release
--
-- The wire format does NOT change -- the v1.7.0 meta page is
-- byte-identical to v1.6.x (`MetaPageData::version = 3`). The
-- only on-disk-visible change is that the meta page is now
-- stamped after every chain page, where previously it was
-- written first; readers see no difference because they only
-- examine the post-build state.
--
-- See docs/UPGRADING.md for the v1.6 -> v1.7 upgrade row (no
-- REINDEX needed). Existing v1.6.x indexes continue to work
-- unchanged; the v1.7.0 binary's ambuild path simply uses less
-- memory during the build.
--
-- This migration file exists only so the upgrade path
-- `ALTER EXTENSION pg_turbovec UPDATE TO '1.7.0';` resolves
-- without an error. It is intentionally empty: there are no
-- new SQL objects, no changed signatures, and no removed
-- objects in v1.7.0 vs v1.6.x.