bigquery: ARROW query_and_wait returns empty result on cached large-result queries #18935

________ test_query_and_wait_arrow_cached_results[too_large_for_inline] ________
[gw1] linux -- Python 3.12.12 /tmpfs/src/github/google-cloud-python/packages/google-cloud-bigquery/.nox/system-3-12/bin/python

bigquery_client = 
priority = None, page_size = None, num_rows = 20000, payload_size = 1024

    @pytest.mark.parametrize(
        ("priority", "page_size", "num_rows", "payload_size"),
        [
            (None, 100, 1000, 0),
            # The results are too large to return inline, so the cached jobs.query
            # response has no rows and totalRows is 0.
            (None, None, 20000, 1024),
            (enums.QueryPriority.INTERACTIVE, 100, 1000, 0),
        ],
        ids=["some_rows_inline", "too_large_for_inline", "no_rows_inline"],
    )
    def test_query_and_wait_arrow_cached_results(
        bigquery_client, priority, page_size, num_rows, payload_size
    ):
        # No other query uses this literal, so only the second run can hit the
        # cache.
        query = (
            f"SELECT x, '{uuid.uuid4().hex}' AS key, REPEAT('x', {payload_size}) AS p "
            f"FROM UNNEST(GENERATE_ARRAY(1, {num_rows})) AS x ORDER BY x"
        )
        job_config = bigquery.QueryJobConfig(use_query_cache=True)
        if priority is not None:
            job_config.priority = priority
    
        def read():
            rows = bigquery_client.query_and_wait(
                query,
                job_config=job_config,
                page_size=page_size,
                query_results_format=enums.QueryResultsFormat.ARROW,
            )
            table = pyarrow.Table.from_batches(list(rows.to_arrow_iterable()))
            return bigquery_client.get_job(rows.job_id, location=rows.location), table
    
        first_job, first = read()
        cached_job, cached = read()
    
        assert not first_job.cache_hit
        assert cached_job.cache_hit
>       assert cached.num_rows == num_rows
E       assert 0 == 20000
E        +  where 0 = pyarrow.Table\n\n----.num_rows