From 75bde11360dfb839a13a749ce53cc69f99dda088 Mon Sep 17 00:00:00 2001
From: Alexey Milovidov <milovidov@yandex-team.ru>
Date: Thu, 29 Oct 2015 07:13:18 +0300
Subject: [PATCH] dbms: implemented TODO [#METR-18564].

---
 .../DB/AggregateFunctions/AggregateFunctionUniq.h    | 12 ++++++++++--
 .../AggregateFunctions/AggregateFunctionsUniq.cpp    |  2 +-
 2 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/dbms/include/DB/AggregateFunctions/AggregateFunctionUniq.h b/dbms/include/DB/AggregateFunctions/AggregateFunctionUniq.h
index dfd18f203d1..6766f065f1a 100644
--- a/dbms/include/DB/AggregateFunctions/AggregateFunctionUniq.h
+++ b/dbms/include/DB/AggregateFunctions/AggregateFunctionUniq.h
@@ -39,6 +39,7 @@ struct AggregateFunctionUniqUniquesHashSetData
 	static String getName() { return "uniq"; }
 };
 
+/// Для функции, принимающей несколько аргументов. Такая функция сама заранее их хэширует, поэтому здесь используется TrivialHash.
 struct AggregateFunctionUniqUniquesHashSetDataForVariadic
 {
 	typedef UniquesHashSet<TrivialHash> Set;
@@ -68,6 +69,15 @@ struct AggregateFunctionUniqHLL12Data<String>
 	static String getName() { return "uniqHLL12"; }
 };
 
+struct AggregateFunctionUniqHLL12DataForVariadic
+{
+	typedef HyperLogLogWithSmallSetOptimization<UInt64, 16, 12, TrivialHash> Set;
+	Set set;
+
+	static String getName() { return "uniqHLL12"; }
+};
+
+
 /// uniqExact
 
 template <typename T>
@@ -361,8 +371,6 @@ public:
 /** Для нескольких аргументов. Для вычисления, хэширует их.
   * Можно передать несколько аргументов как есть; также можно передать один аргумент - кортеж.
   * Но (для возможности эффективной реализации), нельзя передать несколько аргументов, среди которых есть кортежи.
-  *
-  * TODO В Data для uniqHLL12 и uniqCombined должен использоваться TrivialHash.
   */
 template <typename Data, bool argument_is_tuple>
 class AggregateFunctionUniqVariadic final : public IAggregateFunctionHelper<Data>
diff --git a/dbms/src/AggregateFunctions/AggregateFunctionsUniq.cpp b/dbms/src/AggregateFunctions/AggregateFunctionsUniq.cpp
index b108474d796..01def64d5dd 100644
--- a/dbms/src/AggregateFunctions/AggregateFunctionsUniq.cpp
+++ b/dbms/src/AggregateFunctions/AggregateFunctionsUniq.cpp
@@ -96,7 +96,7 @@ void registerAggregateFunctionsUniq(AggregateFunctionFactory & factory)
 		createAggregateFunctionUniq<AggregateFunctionUniqUniquesHashSetData, AggregateFunctionUniqUniquesHashSetDataForVariadic>);
 
 	factory.registerFunction({"uniqHLL12"},
-		createAggregateFunctionUniq<AggregateFunctionUniqHLL12Data, AggregateFunctionUniqHLL12Data<UInt64>>);
+		createAggregateFunctionUniq<AggregateFunctionUniqHLL12Data, AggregateFunctionUniqHLL12DataForVariadic>);
 
 	factory.registerFunction({"uniqExact"},
 		createAggregateFunctionUniq<AggregateFunctionUniqExactData, AggregateFunctionUniqExactData<String>>);