DROP TABLE IF EXISTS test; CREATE TABLE test (k UInt64, v String) ENGINE = MergeTree ORDER BY k; INSERT INTO test SELECT number, toString(number) FROM numbers(100); SET allow_experimental_parallel_reading_from_replicas = 2, max_parallel_replicas = 3, prefer_localhost_replica = 0, parallel_replicas_for_non_replicated_merge_tree=1, cluster_for_parallel_replicas='test_cluster_one_shard_three_replicas_localhost'; -- default coordinator SELECT count(), sum(k) FROM test SETTINGS log_comment = '02950_parallel_replicas_used_replicas_count'; SYSTEM FLUSH LOGS; SELECT ProfileEvents['ParallelReplicasUsedCount'] FROM system.query_log WHERE type = 'QueryFinish' AND query_id IN (SELECT query_id FROM system.query_log WHERE current_database = currentDatabase() AND log_comment = '02950_parallel_replicas_used_replicas_count' AND type = 'QueryFinish' AND initial_query_id = query_id) SETTINGS allow_experimental_parallel_reading_from_replicas=0; -- In order coordinator SELECT k FROM test order by k limit 5 offset 89 SETTINGS optimize_read_in_order=1, log_comment='02950_parallel_replicas_used_replicas_count_2'; SYSTEM FLUSH LOGS; SELECT ProfileEvents['ParallelReplicasUsedCount'] FROM system.query_log WHERE type = 'QueryFinish' AND query_id IN (SELECT query_id FROM system.query_log WHERE current_database = currentDatabase() AND log_comment = '02950_parallel_replicas_used_replicas_count_2' AND type = 'QueryFinish' AND initial_query_id = query_id) SETTINGS allow_experimental_parallel_reading_from_replicas=0; DROP TABLE test;