```sql
DROP TABLE IF EXISTS tp;

create table tp (d1 Int32, d2 Int32, eventcnt Int64,
projection p (select sum(eventcnt), d1 group by d1)) 
engine = SummingMergeTree order by (d1, d2);

set allow_experimental_projection_optimization = 1, force_optimize_projection = 1;

select sum(eventcnt) eventcnt, d1
from tp
group by d1;

DB::Exception: No projection is used when allow_experimental_projection_optimization = 1.

```

The exception message is also incorrect, should be "when force_optimize_projection = 1".

++adaptive_parts;
    }
    size_t index_granularity_bytes = 0;
    if (adaptive_parts > parts.size() / 2)
        index_granularity_bytes = data_settings->index_granularity_bytes;
    const size_t max_marks_to_use_cache = roundRowsOrBytesToMarks(
        settings.merge_tree_max_rows_to_use_cache,
        settings.merge_tree_max_bytes_to_use_cache,
        data_settings->index_granularity,
        index_granularity_bytes);
    const size_t min_marks_for_concurrent_read = minMarksForConcurrentRead(
        settings.merge_tree_min_rows_for_concurrent_read,
        settings.merge_tree_min_bytes_for_concurrent_read,
        data_settings->index_granularity,
        index_granularity_bytes,
        sum_marks);
    if (sum_marks > max_marks_to_use_cache)
        use_uncompressed_cache = false;
    if (0 == sum_marks)
        return {};
    ReadFromMergeTree::Settings step_settings
    {
        .max_block_size = max_block_size,
        .preferred_block_size_bytes = settings.preferred_block_size_bytes,
        .preferred_max_column_in_block_size_bytes = settings.preferred_max_column_in_block_size_bytes,
        .min_marks_for_concurrent_read = min_marks_for_concurrent_read,
        .use_uncompressed_cache = use_uncompressed_cache,
        .reader_settings = reader_settings,
        .backoff_settings = MergeTreeReadPool::BackoffSettings(settings),
    };