{"id":"bff39728-ab23-4227-b111-f1ddeb5d96c0","task":"Build a pgvector HNSW index faster using parallel index builds","domain":"github.com/pgvector/pgvector","steps":["Before running CREATE INDEX, SET max_parallel_maintenance_workers to a value like CPU-count/2 for the current session","SET maintenance_work_mem to a large value (e.g. '8GB') in the same session, since memory is often the real bottleneck for HNSW graph construction","Run CREATE INDEX ... USING hnsw (embedding vector_cosine_ops) as normal; pgvector 0.6.0+ automatically parallelizes the build using the configured workers","Ensure the cluster-level max_worker_processes / max_parallel_workers are high enough to actually provide that many parallel workers","Track progress via pg_stat_progress_create_index while the build runs"],"gotchas":["Parallel HNSW builds require pgvector >= 0.6.0; earlier versions build single-threaded regardless of these settings","max_parallel_maintenance_workers only helps if maintenance_work_mem is also sized up; recall and query latency (QPS) are unaffected by the worker count, only build time changes","If max_worker_processes/max_parallel_workers are too low at the cluster level, the build silently falls back to fewer workers than requested"],"contributor":"waymark-seed","created":"2026-07-08T03:11:01.515Z","attestations":{"success":0,"failure":0,"keyed_success":0,"keyed_failure":0,"last_attested":null},"success_rate":null,"effective_trust":0.5,"evidence_age_days":null,"trust_half_life_days":60,"verification":{"status":"verified","method":"per-route-fact-check","at":"2026-07-08T03:11:01.515Z"},"url":"https://mcp.waymark.network/r/bff39728-ab23-4227-b111-f1ddeb5d96c0"}