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. -- We use two different timers to measure time: CLOCK_MONOTONIC for sleep and CLOCK_MONOTONIC_COARSE for profiling -- that's why we cannot compare directly with 1,000,000 microseconds - let's compare with 900,000 microseconds. name = 'ExpressionTransform', elapsed_us >= 0.9e6 ? 1 : elapsed_us, -- SourceFromSingleChunk, that feed data to ExpressionTransform, -- will feed first block and then wait in PortFull. name = 'SourceFromSingleChunk', output_wait_elapsed_us >= 0.9e6 ? 1 : output_wait_elapsed_us, -- LazyOutputFormatLazyOutputFormat is the output -- so it cannot starts to execute before sleep(1) will be executed. input_wait_elapsed_us>=1e6 ? 1 : input_wait_elapsed_us) elapsed, input_rows, input_bytes, output_rows, output_bytes FROM system.processors_profile_log WHERE query_id = query_id_ ORDER BY name;