-- { echo }
EXPLAIN PIPELINE SELECT sleep(1);
(Expression)
ExpressionTransform
  (ReadFromStorage)
  SourceFromSingleChunk 0 → 1
SELECT sleep(1) SETTINGS log_processors_profiles=true, log_queries=1, log_queries_min_type='QUERY_FINISH';
0
SYSTEM FLUSH LOGS;
WITH
    (
        SELECT query_id
        FROM system.query_log
        WHERE current_database = currentDatabase() AND Settings['log_processors_profiles']='1'
    ) AS query_id_
SELECT
    name,
    multiIf(
        -- ExpressionTransform executes sleep(),
        -- so IProcessor::work() will spend 1 sec.
        name = 'ExpressionTransform', elapsed_us>1e6,
        -- SourceFromSingleChunk, that feed data to ExpressionTransform,
        -- will feed first block and then wait in PortFull.
        name = 'SourceFromSingleChunk', output_wait_elapsed_us>1e6,
        -- NullSource/LazyOutputFormatLazyOutputFormat are the outputs
        -- so they cannot starts to execute before sleep(1) will be executed.
        input_wait_elapsed_us>1e6)
    elapsed
FROM system.processors_profile_log
WHERE query_id = query_id_
ORDER BY name;
ExpressionTransform	1
LazyOutputFormat	1
LimitsCheckingTransform	1
NullSource	1
NullSource	1
SourceFromSingleChunk	1