-- { echo } EXPLAIN PIPELINE SELECT sleep(1); SELECT sleep(1) SETTINGS log_processors_profiles=true, log_queries=1, log_queries_min_type='QUERY_FINISH'; 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, input_rows, input_bytes, output_rows, output_bytes FROM system.processors_profile_log WHERE query_id = query_id_ ORDER BY name;