pgvector HNSW compatibility profile

This directory vendors the dense vector and halfvec L2, inner-product, cosine, and L1 portions of pgvector’s upstream HNSW regression tests. The fixtures are derived from pgvector 0.8.3 (upstream commit represented by the repository’s certified reference snapshot) and retain pgvector’s PostgreSQL license in LICENSE.pgvector.

The only semantic adaptation is index DDL: source columns and query operators remain pgvector-owned, while USING hnsw and pgvector’s HNSW opclasses are replaced with USING pgcontext_hnsw and the companion bridge opclasses. This matches pgContext’s migration contract: applications keep their existing pgvector columns and SQL but explicitly build a pgContext index.

Run the profile against a PostgreSQL 17 server with vector, pgcontext, and pgcontext_pgvector installed:

scripts/check-pgvector-regression-compat.sh

This is intentionally a bounded HNSW compatibility profile, not a claim that pgContext implements pgvector’s IVFFlat access method or pgvector-specific HNSW GUCs.