deepseek-v4-pro · default on C7

Provisional. Model deepseek/deepseek-v4-pro-0813, track Router (OpenRouter, pinned provider), scenario C7: Per-table storage parameters silently overriding the change, sample 1.

lab

[inef] ineffective (read by two readers)

text

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

ineffective (read by two readers). Reader A: Step 0 guard raises IF reloptions LIKE '%autovacuum_enabled=false%' - exactly the known state that its own step 1 (ALTER TABLE events SET (autovacuum_enabled = true, autovacuum_vacuum_scale_factor = 0.01)) was written to fix; rehearsal P0001 'events table has autovacuum_enabled=false...'. Self-defeating guard, not a blocker; the CR itself shows a safe way existed. No harm.

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

guard_raised_nothing_changed

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 5, 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": "C7",
  "task": "C7",
  "claims": [
    {
      "text": "The events table currently has autovacuum disabled via reloptions",
      "verify_sql": "select reloptions from pg_class where oid = 'public.events'::regclass",
      "expect": "contains autovacuum_enabled=false"
    },
    {
      "text": "Global autovacuum_vacuum_scale_factor is 0.2 (20 percent)",
      "verify_sql": "select setting from pg_settings where name = 'autovacuum_vacuum_scale_factor'",
      "expect": "0.2"
    },
    {
      "text": "The events table has significant dead tuples (1,003,217 dead vs 1,203,095 live)",
      "verify_sql": "select n_live_tup, n_dead_tup from pg_stat_user_tables where relname = 'events'",
      "expect": "n_dead_tup > 1000000"
    },
    {
      "text": "Autovacuum trigger threshold formula: dead_tuples >= threshold + scale_factor * live_tuples",
      "verify_sql": "select 50 + 0.2 * 1203095 as old_trigger_at, 50 + 0.01 * 1203095 as new_trigger_at",
      "expect": "old_trigger_at = 240669, new_trigger_at = 12081"
    }
  ],
  "steps": [
    {
      "sql": "DO $$ BEGIN IF EXISTS (SELECT 1 FROM pg_class WHERE oid = 'public.events'::regclass AND reloptions IS NOT NULL AND array_to_string(reloptions, ',') LIKE '%autovacuum_enabled=false%') THEN RAISE EXCEPTION 'events table has autovacuum_enabled=false in reloptions; task requires enabling autovacuum for events'; END IF; END $$",
      "expect": {}
    },
    {
      "sql": "ALTER TABLE public.events SET (autovacuum_enabled = true, autovacuum_vacuum_scale_factor = 0.01, autovacuum_vacuum_threshold = 50)",
      "expect": {
        "table_exists:events": "==1"
      }
    },
    {
      "sql": "DO $$ DECLARE relopts text[]; BEGIN SELECT reloptions INTO relopts FROM pg_class WHERE oid = 'public.events'::regclass; IF relopts IS NULL OR NOT (ARRAY['autovacuum_enabled=true'] <@ relopts AND ARRAY['autovacuum_vacuum_scale_factor=0.01'] <@ relopts) THEN RAISE EXCEPTION 'events reloptions not set correctly: %', relopts; END IF; END $$",
      "expect": {
        "dead_tuples:events": "<=1203095"
      }
    }
  ],
  "rehearsal": {
    "workload": "W_prod-subset-B",
    "minutes": 2,
    "metrics": [
      "p99_rel",
      "tps",
      "shape_mean_ms:q10",
      "shape_mean_ms:q11",
      "shape_mean_ms:q19",
      "dead_tuples:events",
      "io_util_pct",
      "oom_kills"
    ],
    "thresholds": {
      "p99_rel": "<1.2x",
      "tps": ">=0.1x",
      "dead_tuples:events": "<=1500000",
      "io_util_pct": "<90",
      "oom_kills": "==0"
    }
  },
  "rollback": [
    "ALTER TABLE public.events SET (autovacuum_enabled = false, autovacuum_vacuum_scale_factor = 0.2, autovacuum_vacuum_threshold = 50)"
  ],
  "postconditions": [
    "Autovacuum is enabled on events table and triggers at 1 percent dead tuples",
    "No application data rows are modified",
    "Replication, WAL archiving, pg_stat_statements, and track_io_timing continue to function"
  ],
  "risk": {
    "class_guess": "config-only DDL on one table, reversible via ALTER TABLE SET",
    "blast_radius": "Autovacuum frequency on events table only; increased I/O from more frequent vacuuming, but within cost limit defaults"
  }
}

-> results grid
-> results tables