DROP TABLE IF EXISTS test; CREATE TABLE test (s String) ENGINE = MergeTree ORDER BY s SETTINGS index_granularity = 1; INSERT INTO test SELECT randomString(1000) FROM numbers(100000); SELECT round(primary_key_bytes_in_memory, -7), round(primary_key_bytes_in_memory_allocated, -7) FROM system.parts WHERE database = currentDatabase() AND table = 'test'; SYSTEM UNLOAD PRIMARY KEY {CLICKHOUSE_DATABASE:Identifier}.test; SELECT primary_key_bytes_in_memory, primary_key_bytes_in_memory_allocated FROM system.parts WHERE database = currentDatabase() AND table = 'test'; DROP TABLE IF EXISTS test2; CREATE TABLE test2 (s String) ENGINE = MergeTree ORDER BY s SETTINGS index_granularity = 1; INSERT INTO test2 SELECT randomString(1000) FROM numbers(100000); SELECT round(primary_key_bytes_in_memory, -7), round(primary_key_bytes_in_memory_allocated, -7) FROM system.parts WHERE database = currentDatabase() AND table IN ('test', 'test2'); SELECT s != '' FROM test LIMIT 1; SELECT round(primary_key_bytes_in_memory, -7), round(primary_key_bytes_in_memory_allocated, -7) FROM system.parts WHERE database = currentDatabase() AND table IN ('test', 'test2'); SYSTEM UNLOAD PRIMARY KEY; SELECT primary_key_bytes_in_memory, primary_key_bytes_in_memory_allocated FROM system.parts WHERE database = currentDatabase() AND table IN ('test', 'test2');