```
CREATE TABLE t (x UInt8, PROJECTION p (SELECT x GROUP BY x)) ENGINE = MergeTree ORDER BY ();
INSERT INTO t VALUES (0);

SET group_by_overflow_mode = 'any', max_rows_to_group_by = 1000, totals_mode = 'after_having_auto';
SELECT x FROM t GROUP BY x WITH TOTALS;
```
{
    auto lock = lockParts();
    return getPartIfExistsUnlocked(part_info, valid_states, lock);
}
MergeTreeData::DataPartPtr MergeTreeData::getPartIfExists(const String & part_name, const MergeTreeData::DataPartStates & valid_states)