Describe the bug

With native psql + knex, when querying a table with jsonb columns, the resulting rows deserialize the data into an object instead of a string. This causes jest to fail with queries that select jsonb. The same also happens with bigint where the value as returned by knex is string with psql but is a number with pg-mem.

Example failure diff generated by jest:

    - Expected  - 22
    + Received  +  7

      Object {
    -   "created_at": "2025-08-04T19:35:53.957Z",
    -   "extras": Object {
    -     "deripio": "h",
    -     "vito": "e",
    -   },
    +   "created_at": 2025-08-04T19:35:53.957Z,
    +   "extras": "{\"deripio\":\"h\",\"vito\":\"e\"}",
        "fcm_token": "colo utrimque creo temeritas sto tenuis adduco caveo uterq
ue thorax",
    -   "id": "581042995298846",
    +   "id": 581042995298846,
        "id_token": "Administratio aetas velut ara perferendis barba quas. Verus
 ipsam colligo volubilis. Comburo tunc exercitationem aperiam nobis.",
    -   "last_updated_at": "2025-07-26T12:44:05.531Z",
    +   "last_updated_at": 2025-07-26T12:44:05.531Z,
        "phone_number": "+16155297995",
    -   "profile": Object {
    -     "comparo": "G",
    -   },
    +   "profile": "{\"comparo\":\"G\"}",
        "profile_updated_at": null,
    -   "summary": Object {
    -     "odio": "P",
    -     "pecto": "F",
    -     "universe": "J",
    -   },
    -   "tags": Object {
    -     "tags": Array [
    -       "valens",
    -       "utilis",
    -       "uterque",
    -     ],
    -   },
    +   "summary": "{\"pecto\":\"F\",\"odio\":\"P\",\"universe\":\"J\"}",
    +   "tags": "{\"tags\":[\"valens\",\"utilis\",\"uterque\"]}",
      }

To Reproduce

Minimal example using knex:

export async function createAndSeedTable() {
  await knex.schema.createTable('worker', async (table) => {
    table.specificType('id', 'BIGSERIAL').primary();
    table.jsonb('profile').notNullable().index();
    table.timestamp('created_at').defaultTo(knex.fn.now()).notNullable().index();
  });

  const worker = {
    "id":  "1",
    "profile": { "name": "John Doe" },
    "created_at": "2025-07-26T12:44:05.531Z",
  };
  const insertedRecord = await knex('worker').insert(worker).returning('*');
  console.log(typeof insertedRecord.id) // "number"
  console.log(typeof insertedRecord.profile) // "string"
}

pg-mem version

3.0.5