From 32a2ec00d1c69da03cbbf5d4c48b0551cee21543 Mon Sep 17 00:00:00 2001
From: Alexey Milovidov <milovidov@yandex-team.ru>
Date: Wed, 24 Dec 2014 22:00:14 +0300
Subject: [PATCH] dbms: more scalable aggragator: preparation [#METR-2944].

---
 .../DB/Common/HashTable/TwoLevelHashMap.h     | 55 +++++++++++++++++++
 .../DB/Interpreters/AggregationCommon.h       |  1 +
 2 files changed, 56 insertions(+)
 create mode 100644 dbms/include/DB/Common/HashTable/TwoLevelHashMap.h

diff --git a/dbms/include/DB/Common/HashTable/TwoLevelHashMap.h b/dbms/include/DB/Common/HashTable/TwoLevelHashMap.h
new file mode 100644
index 00000000000..0e9a4d0919c
--- /dev/null
+++ b/dbms/include/DB/Common/HashTable/TwoLevelHashMap.h
@@ -0,0 +1,55 @@
+#pragma once
+
+#include <DB/Common/HashTable/TwoLevelHashTable.h>
+#include <DB/Common/HashTable/HashMap.h>
+
+
+template
+<
+	typename Key,
+	typename Cell,
+	typename Hash = DefaultHash<Key>,
+	typename Grower = HashTableGrower<8>,
+	typename Allocator = HashTableAllocator
+>
+class TwoLevelHashMapTable : public TwoLevelHashTable<Key, Cell, Hash, Grower, Allocator, HashMapTable<Key, Cell, Hash, Grower, Allocator> >
+{
+public:
+	typedef Key key_type;
+	typedef typename Cell::Mapped mapped_type;
+	typedef typename Cell::value_type value_type;
+
+	mapped_type & operator[](Key x)
+	{
+		typename TwoLevelHashMapTable::iterator it;
+		bool inserted;
+		this->emplace(x, it, inserted);
+
+		if (!__has_trivial_constructor(mapped_type) && inserted)
+			new(&it->second) mapped_type();
+
+		return it->second;
+	}
+};
+
+
+template
+<
+	typename Key,
+	typename Mapped,
+	typename Hash = DefaultHash<Key>,
+	typename Grower = HashTableGrower<8>,
+	typename Allocator = HashTableAllocator
+>
+using TwoLevelHashMap = TwoLevelHashMapTable<Key, HashMapCell<Key, Mapped, Hash>, Hash, Grower, Allocator>;
+
+
+template
+<
+	typename Key,
+	typename Mapped,
+	typename Hash = DefaultHash<Key>,
+	typename Grower = HashTableGrower<8>,
+	typename Allocator = HashTableAllocator
+>
+using TwoLevelHashMapWithSavedHash =  TwoLevelHashMapTable<Key, HashMapCellWithSavedHash<Key, Mapped, Hash>, Hash, Grower, Allocator>;
diff --git a/dbms/include/DB/Interpreters/AggregationCommon.h b/dbms/include/DB/Interpreters/AggregationCommon.h
index f1f56a81aa6..5d06d11c03a 100644
--- a/dbms/include/DB/Interpreters/AggregationCommon.h
+++ b/dbms/include/DB/Interpreters/AggregationCommon.h
@@ -10,6 +10,7 @@
 #include <DB/Core/StringRef.h>
 #include <DB/Columns/IColumn.h>
 #include <DB/Common/HashTable/HashMap.h>
+#include <DB/Common/HashTable/TwoLevelHashMap.h>
 
 
 template <>