sessions_database = 
database_dialect = 
def test_execute_partitioned_dml(sessions_database, database_dialect):
    # [START spanner_test_dml_partioned_dml_update]
    sd = _sample_data
    param_types = spanner_v1.param_types

    delete_statement = f"DELETE FROM {sd.TABLE} WHERE true"

    def _setup_table(txn):
        txn.execute_update(delete_statement)
        for insert_statement in _generate_insert_statements():
            txn.execute_update(insert_statement)

    committed = sessions_database.run_in_transaction(_setup_table)

    with sessions_database.snapshot(read_timestamp=committed) as snapshot:
        before_pdml = list(snapshot.read(sd.TABLE, sd.COLUMNS, sd.ALL))

    sd._check_rows_data(before_pdml)

    keys = (
        ["p1", "p2"]
        if database_dialect == DatabaseDialect.POSTGRESQL
        else ["email", "target"]
    )
    placeholders = (
        ["$1", "$2"]
        if database_dialect == DatabaseDialect.POSTGRESQL
        else [f"@{key}" for key in keys]
    )
    nonesuch = "nonesuch@example.com"
    target = "phred@example.com"
    update_statement = (
        f"UPDATE contacts SET email = {placeholders[0]} WHERE email = {placeholders[1]}"
    )

    row_count = sessions_database.execute_partitioned_dml(
        update_statement,
        params={keys[0]: nonesuch, keys[1]: target},
        param_types={keys[0]: param_types.STRING, keys[1]: param_types.STRING},
        request_options=spanner_v1.RequestOptions(
            priority=spanner_v1.RequestOptions.Priority.PRIORITY_MEDIUM
        ),
    )
    assert row_count == 1

    row = sd.ROW_DATA[0]
    updated = [row[:3] + (nonesuch,)] + list(sd.ROW_DATA[1:])

    with sessions_database.snapshot(read_timestamp=committed) as snapshot:
        after_update = list(snapshot.read(sd.TABLE, sd.COLUMNS, sd.ALL))
    sd._check_rows_data(after_update, updated)

    row_count = sessions_database.execute_partitioned_dml(delete_statement)


  assert row_count == len(sd.ROW_DATA)


E       AssertionError: assert 0 == 3

E        +  where 3 = len(((1, 'Phred', 'Phlyntstone', 'phred@example.com'), (2, 'Bharney', 'Rhubble', 'bharney@example.com'), (3, 'Wylma', 'Phlyntstone', 'wylma@example.com')))

E        +    where ((1, 'Phred', 'Phlyntstone', 'phred@example.com'), (2, 'Bharney', 'Rhubble', 'bharney@example.com'), (3, 'Wylma', 'Phlyntstone', 'wylma@example.com')) = <module 'tests.system._sample_data' from '/tmpfs/src/github/python-spanner/tests/system/_sample_data.py'>.ROW_DATA
tests/system/test_session_api.py:1180: AssertionError