vector-search-empty

Vector search with permissions comes back empty

pgvector's HNSW scan picks its nearest candidates before a permission filter runs. When the passages nearest the question belong to documents the searcher cannot read, the filter leaves nothing. Iterative scans keep walking, within two budgets: hnsw.max_scan_tuples and hnsw.scan_mem_multiplier (a multiple of work_mem).

• setup.sql: 100,000 synthetic passages (384 dimensions); 3,000 unreadable ones crowd the query, 5 readable ones sit further out.
• queries.sql: plain HNSW (0), ef_search 1,000 (0), iterative scan (5), and where a distance cutoff belongs.
• limit.sql: 30,000 more unreadable passages: the iterative scan returns 0 until both budgets are raised.
• stuga-probe.integration.test.ts: the same crowd through Stuga's own search, before and after its fix.

Postgres 18 with pgvector 0.8.6:

psql -d throwaway -f setup.sql
psql -d throwaway -f queries.sql
psql -d throwaway -f limit.sql

Timings come from one Apple-silicon machine and vary by hardware; counts do not. Each file ends with its output from 2026-10-02.