-- pg_turbovec v1.10.0 -- IVF coarse-quantizer layer.
--
-- This file is a *reference mirror*. The authoritative install
-- script is generated by `cargo pgrx schema`.
--
-- v1.10.0 adds an inverted-file (IVF) ANN structure over the
-- quantized codes. It is the first wire-format
-- change since v1.4.0: MetaPageData::version 3 -> 4.
--
-- ** Existing v3 indexes do NOT need a REINDEX. ** A v1.10.0 binary
-- reads a v3 index as a flat (lists=0) index, byte-compatible. Only
-- users who WANT IVF rebuild with the new reloption:
--
--   CREATE INDEX ... USING turbovec (emb vec_cosine_ops)
--     WITH (bit_width = 4, lists = 1024 [, assign_dups = 2]);
--
-- New SQL surface (all additive; emitted by cargo pgrx schema):
--   reloption  lists        int  default 0  (0 = flat; N = IVF cells, ~sqrt(n))
--   reloption  assign_dups  int  default 1  (1 = single; M = soft multi-assign)
--   GUC turbovec.probes      int default 8   (cells scanned per query)
--   GUC turbovec.max_probes  int default 64  (iterative-scan probe-widening cap)
--
-- IVF turns the flat O(n*dim) scan into a coarse search over `lists`
-- centroids + a fine search restricted to the `probes` nearest cells,
-- so query work drops to roughly (probes/lists) of the corpus. probes
-- is the recall/latency dial; probes >= lists reduces to the exact
-- flat scan.
--
-- There is no DDL or on-disk migration for existing indexes. The
-- upgrade path `ALTER EXTENSION pg_turbovec UPDATE TO '1.10.0';`
-- resolves against this file plus the cargo-pgrx-generated reloption/
-- GUC registration. No REINDEX required unless you opt into IVF.