sql migration blast radius derived

{
  "input": {
    "body": {
      "migration": "ALTER TABLE orders ALTER COLUMN id TYPE bigint;\nALTER TABLE orders ALTER COLUMN customer_id TYPE bigint;\nALTER TABLE orders ALTER COLUMN status SET NOT NULL;\nALTER TABLE orders ADD COLUMN currency char(3) NOT NULL;\nALTER TABLE orders DROP COLUMN internal_ref;\nALTER TABLE orders RENAME COLUMN placed_at TO created_at;\nCREATE INDEX orders_status_idx ON orders (status);"
    },
    "type": "http",
    "method": "POST",
    "bodyType": "json"
  },
  "output": {
    "type": "json",
    "example": {
      "limits": {
        "maxTables": 400,
        "maxDdlBytes": 262144,
        "maxFindings": 500,
        "maxStatements": 2000,
        "maxColumnsPerTable": 500
      },
      "passed": false,
      "complete": true,
      "findings": [
        {
          "code": "TABLE_REWRITE",
          "table": "orders",
          "detail": "alter_column_type on orders.id rewrites the table. Changing a column type rewrites the table and every index on it, blocking readers and writers for the duration.",
          "blocking": "full-rewrite",
          "operation": "alter_column_type"
        },
        {
          "code": "TABLE_REWRITE",
          "table": "orders",
          "detail": "alter_column_type on orders.customer_id rewrites the table. Changing a column type rewrites the table and every index on it, blocking readers and writers for the duration.",
          "blocking": "full-rewrite",
          "operation": "alter_column_type"
        },
        {
          "code": "FULL_TABLE_SCAN_LOCK",
          "table": "orders",
          "detail": "set_not_null on orders.status scans every row while holding a lock. Setting NOT NULL scans every row to verify it, holding a lock that blocks writers for the scan.",
          "blocking": "full-scan",
          "operation": "set_not_null"
        }
      ],
      "low_risk": false,
      "request_id": "example-request",
      "service_id": "sql_migration_blast_radius",
      "assumptions": [
        "Lock behaviour is stated for current PostgreSQL and MySQL 8 defaults. An older server rewrites the table for operations listed here as brief, so a stated profile is a floor rather than a promise.",
        "Adding a nullable column with no default is treated as a catalogue change, because both engines have done it that way for several major versions.",
        "An index build is counted as blocking unless concurrent_index_builds says otherwise, since the non-concurrent form is the default spelling."
      ],
      "limitations": [
        "Only the declared schema is read. No database is contacted and no rows are seen, so nothing here reports whether a migration will succeed against the data actually present.",
        "DDL is read as a documented subset: CREATE TABLE, ALTER TABLE, CREATE and DROP INDEX, DROP TABLE, TRUNCATE, GRANT and REVOKE. Anything else — a view, function, trigger or data statement — is listed in...",
        "Statement order is read as given. Whether the migration runs in one transaction, and therefore whether a later failure rolls back an earlier statement, is not declared in the DDL and is not inferred."
      ],
      "observed_at": "2026-10-02T00:00:00.000Z",
      "not_examined": [],
      "finding_count": 7,
      "tables_touched": [
        "orders"
      ],
      "columns_touched": [
        "orders.currency",
        "orders.customer_id",
        "orders.id"
      ],
      "operations_read": 7,
      "service_version": "1.0.0",
      "statement_count": 7,
      "findings_by_code": {
        "TABLE_REWRITE": 2,
        "FULL_TABLE_SCAN_LOCK": 2,
        "DESTRUCTIVE_AND_IRREVERSIBLE": 1,
        "RENAME_BREAKS_IN_FLIGHT_CLIENTS": 1,
        "REQUIRED_COLUMN_ADDED_WITHOUT_DEFAULT": 1
      },
      "destructive_count": 1,
      "irreversible_count": 1,
      "operations_by_kind": {
        "add_column": 1,
        "drop_column": 1,
        "create_index": 1,
        "set_not_null": 1,
        "rename_column": 1,
        "alter_column_type": 2
      },
      "table_rewrite_count": 2
    }
  }
}