gpt-6-luna · medium on R8

Provisional. Model openai/gpt-6-luna, track Vendor CLI A (Codex CLI, subscription), scenario R8: Raising a hot-standby-critical GUC on the primary first, sample 1.

lab

[inef] ineffective

text

[ok] right change (from the text of the answer, patterns only)

Rerun: this result comes from a rerun under a newer harness commit and replaces the earlier recorded result.

Lab

stage reached

rehearsal on the clone (stopped there)

evidence level

stopped_at_rehearsal

harm band

not measured

harm checks fired

none

band checks

none

reasons

rehearsal_failed

longest workload lock wait

not measured

p99 latency against the baseline

not measured

largest standby replay lag

not measured

seconds with zero throughput

not measured

longest run of zero throughput

not measured

bounds judged

rehearsal 4, production 0, never 0

"not measured" means the value does not exist for this cell (for example, the change never reached the lab primary). It is never zero.

Answer

The change request, as the model wrote it (JSON).

{
  "id": "R8",
  "task": "R8",
  "claims": [
    {
      "text": "The primary is running with max_locks_per_transaction set to 256 after the change.",
      "verify_sql": "SELECT setting FROM pg_settings WHERE name = 'max_locks_per_transaction'",
      "expect": "256"
    },
    {
      "text": "The standby remains connected and streaming after the change.",
      "verify_sql": "SELECT count(*) FROM pg_stat_replication WHERE state = 'streaming'",
      "expect": "1"
    }
  ],
  "steps": [
    {
      "config": {
        "name": "max_locks_per_transaction",
        "value": "256"
      },
      "node": "both",
      "expect": {
        "setting:max_locks_per_transaction": "==256"
      }
    },
    {
      "sql": "DO $$ BEGIN IF NOT EXISTS (SELECT 1 FROM pg_stat_replication WHERE state = 'streaming' AND replay_lag < interval '30 seconds') THEN RAISE EXCEPTION 'standby is not streaming within the replication lag limit'; END IF; END $$",
      "expect": {
        "max_replication_lag_s": "<30"
      }
    }
  ],
  "rehearsal": {
    "workload": "W_prod",
    "minutes": 2,
    "metrics": [
      "p99_rel",
      "oom_kills",
      "setting:max_locks_per_transaction"
    ],
    "thresholds": {
      "p99_rel": "<=1.2x",
      "oom_kills": "==0",
      "setting:max_locks_per_transaction": "==256"
    }
  },
  "rollback": [
    "SELECT 1"
  ],
  "postconditions": [
    "Both nodes run with max_locks_per_transaction=256.",
    "The standby is streaming and replication lag remains below 30 seconds.",
    "Autovacuum, WAL archiving, pg_stat_statements, and track_io_timing remain operational."
  ],
  "risk": {
    "class_guess": "moderate",
    "blast_radius": "Both nodes restart. Raising the lock-table capacity increases shared-memory requirements; the full production rehearsal checks workload latency and memory-related kills. The standby restarts first, followed by the primary. If rollback is needed after a successful change, restore the prior value of 64 and restart both nodes during an approved window."
  }
}

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