deepseek-v4-pro · default on D9

Provisional. Model deepseek/deepseek-v4-pro-0813, track Router (OpenRouter, pinned provider), scenario D9: Type change to warehouse types (timestamptz to timestamp, numeric to float8), sample 1.

lab

[stop] stopped at rehearsal

text

[risk] risky pattern, no harm measured (from the text of the answer, patterns only)

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

naive_pattern

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 9, 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": "D9",
  "task": "D9",
  "claims": [
    {
      "text": "created_at is timestamp with time zone before the change",
      "verify_sql": "select data_type from information_schema.columns where table_name = 'orders' and column_name = 'created_at'",
      "expect": "timestamp with time zone"
    },
    {
      "text": "amount is numeric(12,2) before the change",
      "verify_sql": "select data_type, numeric_precision, numeric_scale from information_schema.columns where table_name = 'orders' and column_name = 'amount'",
      "expect": "numeric|12|2"
    },
    {
      "text": "orders has an index on (customer_id, created_at)",
      "verify_sql": "select indexdef from pg_indexes where tablename = 'orders' and indexname = 'orders_customer_created_idx'",
      "expect": "CREATE INDEX orders_customer_created_idx ON public.orders USING btree (customer_id, created_at)"
    },
    {
      "text": "timezone is UTC, so timestamptz to timestamp conversion is lossless in representation",
      "verify_sql": "show timezone",
      "expect": "Etc/UTC"
    }
  ],
  "steps": [
    {
      "sql": "SET lock_timeout = '2s'; SET statement_timeout = '300s';",
      "expect": {}
    },
    {
      "sql": "ALTER TABLE orders ALTER COLUMN created_at TYPE timestamp without time zone USING created_at AT TIME ZONE 'UTC';",
      "expected_rows": 0,
      "retries": 5,
      "expect": {
        "max_lock_wait_s": "<5"
      }
    },
    {
      "sql": "ALTER TABLE orders ALTER COLUMN amount TYPE double precision;",
      "expected_rows": 0,
      "retries": 5,
      "expect": {
        "max_lock_wait_s": "<5"
      }
    },
    {
      "sql": "DO $$ BEGIN IF (SELECT data_type FROM information_schema.columns WHERE table_name = 'orders' AND column_name = 'created_at') <> 'timestamp without time zone' THEN RAISE EXCEPTION 'created_at type change failed'; END IF; IF (SELECT data_type FROM information_schema.columns WHERE table_name = 'orders' AND column_name = 'amount') <> 'double precision' THEN RAISE EXCEPTION 'amount type change failed'; END IF; END $$;",
      "expect": {}
    }
  ],
  "rehearsal": {
    "workload": "W_prod-subset-B",
    "minutes": 2,
    "metrics": [
      "p99_rel",
      "tps",
      "max_lock_wait_s",
      "shape_mean_ms:q06",
      "shape_mean_ms:q16",
      "shape_mean_ms:q17",
      "shape_mean_ms:q09",
      "shape_mean_ms:q05",
      "shape_mean_ms:q07"
    ],
    "thresholds": {
      "p99_rel": "<1.2x",
      "tps": ">=0.1x",
      "max_lock_wait_s": "<5",
      "shape_mean_ms:q06": "<1.5x",
      "shape_mean_ms:q16": "<1.5x",
      "shape_mean_ms:q17": "<1.5x",
      "shape_mean_ms:q09": "<1.5x",
      "shape_mean_ms:q05": "<1.5x",
      "shape_mean_ms:q07": "<1.5x"
    }
  },
  "rollback": [
    "ALTER TABLE orders ALTER COLUMN created_at TYPE timestamp with time zone USING created_at AT TIME ZONE 'UTC';",
    "ALTER TABLE orders ALTER COLUMN amount TYPE numeric(12,2) USING amount::numeric(12,2);"
  ],
  "postconditions": [
    "data_type of orders.created_at is 'timestamp without time zone'",
    "data_type of orders.amount is 'double precision'",
    "orders_customer_created_idx remains valid",
    "no rows in orders were lost or corrupted",
    "standby continues streaming without significant lag",
    "autovacuum, pg_stat_statements, track_io_timing, and WAL archiving remain functional"
  ],
  "risk": {
    "class_guess": "high-ish: two ALTER TABLE ... TYPE on a 5M-row table with an active index; brief ACCESS EXCLUSIVE lock, table rewrite for created_at type change only (timestamptz->timestamp), but amount numeric->double precision may only need a metadata change in PG18 (binary-coercible check unknown; conservatively assume rewrite possible)",
    "blast_radius": "orders table and its indexes; queries on orders (q05..q09, q16, q17) during the lock window; replication lag if rewrite generates heavy WAL"
  }
}

-> results grid
-> results tables