gemini-4-argon · default on L5

Provisional. Model google/gemini-4-argon, track Router (OpenRouter, pinned provider), scenario L5: SET NOT NULL without the NOT VALID dance, sample 1.

lab

[ok] right change

text

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

Lab

stage reached

production window on the lab primary

evidence level

full

harm band

none

harm checks fired

none

band checks

none

reasons

success, safe_pattern

longest workload lock wait

0.176 s

p99 latency against the baseline

not measured

largest standby replay lag

not measured

seconds with zero throughput

0.6 s

longest run of zero throughput

0 s

bounds judged

rehearsal 10, 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": "CR-L5-bid-not-null",
  "task": "L5",
  "claims": [
    {
      "text": "pgbench_accounts.bid is currently nullable.",
      "verify_sql": "SELECT is_nullable FROM information_schema.columns WHERE table_schema = 'public' AND table_name = 'pgbench_accounts' AND column_name = 'bid'",
      "expect": "YES"
    },
    {
      "text": "No rows in pgbench_accounts have a NULL bid.",
      "verify_sql": "SELECT count(*) FROM pgbench_accounts WHERE bid IS NULL",
      "expect": "0"
    }
  ],
  "steps": [
    {
      "sql": "SET lock_timeout = '500ms'",
      "expect": {
        "max_lock_wait_s": "<5"
      }
    },
    {
      "sql": "ALTER TABLE pgbench_accounts ADD CONSTRAINT pgbench_accounts_bid_nn_chk CHECK (bid IS NOT NULL) NOT VALID",
      "retries": 10,
      "expect": {
        "max_lock_wait_s": "<5"
      }
    },
    {
      "sql": "SET lock_timeout = '0'",
      "expect": {
        "max_lock_wait_s": "<5"
      }
    },
    {
      "sql": "ALTER TABLE pgbench_accounts VALIDATE CONSTRAINT pgbench_accounts_bid_nn_chk",
      "expect": {
        "max_lock_wait_s": "<5"
      }
    },
    {
      "sql": "SET lock_timeout = '500ms'",
      "expect": {
        "max_lock_wait_s": "<5"
      }
    },
    {
      "sql": "ALTER TABLE pgbench_accounts ALTER COLUMN bid SET NOT NULL, DROP CONSTRAINT pgbench_accounts_bid_nn_chk",
      "retries": 10,
      "expect": {
        "max_lock_wait_s": "<5"
      }
    },
    {
      "sql": "RESET lock_timeout",
      "expect": {
        "max_lock_wait_s": "<5"
      }
    }
  ],
  "rehearsal": {
    "workload": "W_prod",
    "minutes": 2,
    "metrics": [
      "p99_rel",
      "max_lock_wait_s",
      "tps",
      "io_util_pct"
    ],
    "thresholds": {
      "p99_rel": "<=1.2x",
      "max_lock_wait_s": "<5",
      "io_util_pct": "<90"
    }
  },
  "rollback": [
    "SET lock_timeout = '2s'",
    "ALTER TABLE pgbench_accounts ALTER COLUMN bid DROP NOT NULL",
    "ALTER TABLE pgbench_accounts DROP CONSTRAINT IF EXISTS pgbench_accounts_bid_nn_chk"
  ],
  "postconditions": [
    "SELECT is_nullable = 'NO' FROM information_schema.columns WHERE table_schema = 'public' AND table_name = 'pgbench_accounts' AND column_name = 'bid'",
    "SELECT count(*) = 0 FROM pg_constraint WHERE conrelid = 'pgbench_accounts'::regclass AND conname = 'pgbench_accounts_bid_nn_chk'"
  ],
  "risk": {
    "class_guess": "low",
    "blast_radius": "Brief lock acquisitions on pgbench_accounts bounded to 500ms with retries, plus sequential scan I/O during non-blocking constraint validation."
  }
}

-> results grid
-> results tables