diff --git a/dbms/include/DB/AggregateFunctions/AggregateFunctionUniqUpTo.h b/dbms/include/DB/AggregateFunctions/AggregateFunctionUniqUpTo.h
index 52605ce7dcc..d182eec0a9b 100644
--- a/dbms/include/DB/AggregateFunctions/AggregateFunctionUniqUpTo.h
+++ b/dbms/include/DB/AggregateFunctions/AggregateFunctionUniqUpTo.h
@@ -202,6 +202,11 @@ private:
 	UInt8 threshold = 5;	/// Значение по-умолчанию, если параметр не указан.
 
 public:
+	size_t sizeOfData() const
+	{
+		return sizeof(AggregateFunctionUniqUpToData<UInt64>) + sizeof(UInt64) * threshold;
+	}
+
 	String getName() const { return "uniqUpTo"; }
 
 	DataTypePtr getReturnType() const
diff --git a/dbms/src/Interpreters/Aggregator.cpp b/dbms/src/Interpreters/Aggregator.cpp
index bb7bff6f616..096f1c92151 100644
--- a/dbms/src/Interpreters/Aggregator.cpp
+++ b/dbms/src/Interpreters/Aggregator.cpp
@@ -1356,11 +1356,15 @@ void NO_INLINE Aggregator::mergeSingleLevelDataImpl(
 			mergeDataImpl<Method>(
 				getDataVariant<Method>(*res).data,
 				getDataVariant<Method>(current).data);
-		else
+		else if (res->without_key)
 			mergeDataNoMoreKeysImpl<Method>(
 				getDataVariant<Method>(*res).data,
 				res->without_key,
 				getDataVariant<Method>(current).data);
+		else
+			mergeDataOnlyExistingKeysImpl<Method>(
+				getDataVariant<Method>(*res).data,
+				getDataVariant<Method>(current).data);
 
 		/// current не будет уничтожать состояния агрегатных функций в деструкторе
 		current.aggregator = nullptr;
diff --git a/dbms/tests/queries/0_stateless/00263_merge_aggregates_and_overflow.reference b/dbms/tests/queries/0_stateless/00263_merge_aggregates_and_overflow.reference
new file mode 100644
index 00000000000..d05b1f927f4
--- /dev/null
+++ b/dbms/tests/queries/0_stateless/00263_merge_aggregates_and_overflow.reference
@@ -0,0 +1 @@
+0	0
diff --git a/dbms/tests/queries/0_stateless/00263_merge_aggregates_and_overflow.sql b/dbms/tests/queries/0_stateless/00263_merge_aggregates_and_overflow.sql
new file mode 100644
index 00000000000..604d89cca1d
--- /dev/null
+++ b/dbms/tests/queries/0_stateless/00263_merge_aggregates_and_overflow.sql
@@ -0,0 +1,12 @@
+DROP TABLE IF EXISTS test.numbers_10k_log;
+
+SET max_block_size = 1000;
+
+CREATE TABLE test.numbers_10k_log ENGINE = Log AS SELECT number FROM system.numbers LIMIT 10000;
+
+SET max_threads = 4;
+SET max_rows_to_group_by = 3000, group_by_overflow_mode = 'any';
+
+SELECT ignore(rand() AS k), ignore(max(toString(number))) FROM test.numbers_10k_log GROUP BY k LIMIT 1;
+
+DROP TABLE test.numbers_10k_log;
diff --git a/dbms/tests/queries/0_stateless/00264_uniq_many_args.reference b/dbms/tests/queries/0_stateless/00264_uniq_many_args.reference
new file mode 100644
index 00000000000..758b4d6b8e2
--- /dev/null
+++ b/dbms/tests/queries/0_stateless/00264_uniq_many_args.reference
@@ -0,0 +1,11 @@
+10	10	100	100	1000	1000	10	10	100	100	1000	1000	10	10	101	101	1006	1006	10	10	100	100	1000	1000	6	6	6	6	6	6
+17	10	10	100	100	610	610	10	10	100	100	610	610	10	10	101	101	616	616	10	10	100	100	610	610	6	6	6	6	6	6	766
+52	10	10	100	100	608	608	10	10	100	100	608	608	10	10	101	101	611	611	10	10	100	100	608	608	6	6	6	6	6	6	766
+5	10	10	100	100	609	609	10	10	100	100	609	609	10	10	101	101	608	608	10	10	100	100	609	609	6	6	6	6	6	6	765
+9	10	10	100	100	608	608	10	10	100	100	608	608	10	10	101	101	618	618	10	10	100	100	608	608	6	6	6	6	6	6	765
+13	10	10	100	100	607	607	10	10	100	100	607	607	10	10	101	101	610	610	10	10	100	100	607	607	6	6	6	6	6	6	765
+46	10	10	100	100	607	607	10	10	100	100	607	607	10	10	101	101	611	611	10	10	100	100	607	607	6	6	6	6	6	6	765
+48	10	10	100	100	609	609	10	10	100	100	609	609	10	10	101	101	617	617	10	10	100	100	609	609	6	6	6	6	6	6	765
+50	10	10	100	100	608	608	10	10	100	100	608	608	10	10	101	101	614	614	10	10	100	100	608	608	6	6	6	6	6	6	765
+54	10	10	100	100	609	609	10	10	100	100	609	609	10	10	101	101	615	615	10	10	100	100	609	609	6	6	6	6	6	6	765
+56	10	10	100	100	608	608	10	10	100	100	608	608	10	10	101	101	614	614	10	10	100	100	608	608	6	6	6	6	6	6	765
diff --git a/dbms/tests/queries/0_stateless/00264_uniq_many_args.sql b/dbms/tests/queries/0_stateless/00264_uniq_many_args.sql
new file mode 100644
index 00000000000..2b24e68910c
--- /dev/null
+++ b/dbms/tests/queries/0_stateless/00264_uniq_many_args.sql
@@ -0,0 +1,35 @@
+SELECT 
+    uniq(x), uniq((x)), uniq(x, y), uniq((x, y)), uniq(x, y, z), uniq((x, y, z)),
+    uniqCombined(x), uniqCombined((x)), uniqCombined(x, y), uniqCombined((x, y)), uniqCombined(x, y, z), uniqCombined((x, y, z)),
+    uniqHLL12(x), uniqHLL12((x)), uniqHLL12(x, y), uniqHLL12((x, y)), uniqHLL12(x, y, z), uniqHLL12((x, y, z)),
+    uniqExact(x), uniqExact((x)), uniqExact(x, y), uniqExact((x, y)), uniqExact(x, y, z), uniqExact((x, y, z)),
+    uniqUpTo(5)(x), uniqUpTo(5)((x)), uniqUpTo(5)(x, y), uniqUpTo(5)((x, y)), uniqUpTo(5)(x, y, z), uniqUpTo(5)((x, y, z))
+FROM
+(
+    SELECT 
+        number % 10 AS x,
+        intDiv(number, 10) % 10 AS y,
+        toString(intDiv(number, 100) % 10) AS z
+    FROM system.numbers LIMIT 1000
+);
+
+
+SELECT k,
+    uniq(x), uniq((x)), uniq(x, y), uniq((x, y)), uniq(x, y, z), uniq((x, y, z)),
+    uniqCombined(x), uniqCombined((x)), uniqCombined(x, y), uniqCombined((x, y)), uniqCombined(x, y, z), uniqCombined((x, y, z)),
+    uniqHLL12(x), uniqHLL12((x)), uniqHLL12(x, y), uniqHLL12((x, y)), uniqHLL12(x, y, z), uniqHLL12((x, y, z)),
+    uniqExact(x), uniqExact((x)), uniqExact(x, y), uniqExact((x, y)), uniqExact(x, y, z), uniqExact((x, y, z)),
+    uniqUpTo(5)(x), uniqUpTo(5)((x)), uniqUpTo(5)(x, y), uniqUpTo(5)((x, y)), uniqUpTo(5)(x, y, z), uniqUpTo(5)((x, y, z)),
+    count() AS c
+FROM
+(
+    SELECT 
+        (number + 0x8ffcbd8257219a26) * 0x66bb3430c06d2353 % 131 AS k,
+        number % 10 AS x,
+        intDiv(number, 10) % 10 AS y,
+        toString(intDiv(number, 100) % 10) AS z
+    FROM system.numbers LIMIT 100000
+)
+GROUP BY k
+ORDER BY c DESC, k ASC
+LIMIT 10;