From 7426542b8b5689238b9ca0b43bebea6d8bfb42c3 Mon Sep 17 00:00:00 2001
From: akonyaev <ka@arenadata.io>
Date: Wed, 23 Oct 2019 11:22:51 +0300
Subject: [PATCH] up precision for avg result to max of type

---
 dbms/src/AggregateFunctions/AggregateFunctionAvg.h    |  5 +----
 dbms/src/DataTypes/DataTypesDecimal.h                 | 11 -----------
 .../00700_decimal_empty_aggregates.reference          |  6 +++---
 3 files changed, 4 insertions(+), 18 deletions(-)

diff --git a/dbms/src/AggregateFunctions/AggregateFunctionAvg.h b/dbms/src/AggregateFunctions/AggregateFunctionAvg.h
index 110b0b38839..13aa9157706 100644
--- a/dbms/src/AggregateFunctions/AggregateFunctionAvg.h
+++ b/dbms/src/AggregateFunctions/AggregateFunctionAvg.h
@@ -52,14 +52,12 @@ public:
     AggregateFunctionAvg(const DataTypes & argument_types_)
         : IAggregateFunctionDataHelper<Data, AggregateFunctionAvg<T, Data>>(argument_types_, {})
         , scale(0)
-        , precision(0)
     {}
 
     /// ctor for Decimals
     AggregateFunctionAvg(const IDataType & data_type, const DataTypes & argument_types_)
         : IAggregateFunctionDataHelper<Data, AggregateFunctionAvg<T, Data>>(argument_types_, {})
         , scale(getDecimalScale(data_type))
-        , precision(getDecimalPrecision(data_type))
     {}
 
     String getName() const override { return "avg"; }
@@ -67,7 +65,7 @@ public:
     DataTypePtr getReturnType() const override
     {
         if constexpr (IsDecimalNumber<T>)
-            return std::make_shared<ResultDataType>(precision, scale);
+            return std::make_shared<ResultDataType>(ResultDataType::maxPrecision(), scale);
         else
             return std::make_shared<ResultDataType>();
     }
@@ -107,7 +105,6 @@ public:
 
 private:
     UInt32 scale;
-    UInt32 precision;
 };
 
 
diff --git a/dbms/src/DataTypes/DataTypesDecimal.h b/dbms/src/DataTypes/DataTypesDecimal.h
index 2626db5db8a..e59a2b6e3fd 100644
--- a/dbms/src/DataTypes/DataTypesDecimal.h
+++ b/dbms/src/DataTypes/DataTypesDecimal.h
@@ -243,17 +243,6 @@ inline UInt32 getDecimalScale(const IDataType & data_type, UInt32 default_value
     return default_value;
 }
 
-inline UInt32 getDecimalPrecision(const IDataType & data_type, UInt32 default_value = std::numeric_limits<UInt32>::max())
-    {
-        if (auto * decimal_type = checkDecimal<Decimal32>(data_type))
-            return decimal_type->getPrecision();
-        if (auto * decimal_type = checkDecimal<Decimal64>(data_type))
-            return decimal_type->getPrecision();
-        if (auto * decimal_type = checkDecimal<Decimal128>(data_type))
-            return decimal_type->getPrecision();
-        return default_value;
-    }
-
 ///
 
 template <typename DataType> constexpr bool IsDataTypeDecimal = false;
diff --git a/dbms/tests/queries/0_stateless/00700_decimal_empty_aggregates.reference b/dbms/tests/queries/0_stateless/00700_decimal_empty_aggregates.reference
index a52fc64e29d..580cf0e26b7 100644
--- a/dbms/tests/queries/0_stateless/00700_decimal_empty_aggregates.reference
+++ b/dbms/tests/queries/0_stateless/00700_decimal_empty_aggregates.reference
@@ -5,9 +5,9 @@
 0.0000	0.0000000	0.00000000	0.0000	0.0000000	0.00000000
 0.0000	0.0000000	0.00000000	0.0000	0.0000000	0.00000000
 0.0000	0.0000000	0.00000000	0.0000	0.0000000	0.00000000
-0.0000	0.0000000	0.00000000	Decimal(6, 4)	Decimal(16, 7)	Decimal(20, 8)
-0.0000	0.0000000	0.00000000	Decimal(6, 4)	Decimal(16, 7)	Decimal(20, 8)
-0.0000	0.0000000	0.00000000	Decimal(6, 4)	Decimal(16, 7)	Decimal(20, 8)
+0.0000	0.0000000	0.00000000	Decimal(9, 4)	Decimal(18, 7)	Decimal(38, 8)
+0.0000	0.0000000	0.00000000	Decimal(9, 4)	Decimal(18, 7)	Decimal(38, 8)
+0.0000	0.0000000	0.00000000	Decimal(9, 4)	Decimal(18, 7)	Decimal(38, 8)
 (0,0,0)	(0,0,0)	(0,0,0)	(0,0,0)	(0,0,0)
 0	0	0
 0	0	0