From 215acf5e5bc0f77e392c6dca7d002dcc5889beb0 Mon Sep 17 00:00:00 2001
From: lhuang09287750 <liang.huang@kyligence.io>
Date: Sun, 9 Oct 2022 05:30:01 +0000
Subject: [PATCH] check the result of conversion for decimal IN float

---
 src/Interpreters/ActionsVisitor.cpp           | 24 +++++++++++++++++--
 src/Interpreters/convertFieldToType.cpp       | 13 +++++-----
 ...ecimal_in_floating_point_literal.reference |  1 +
 3 files changed, 30 insertions(+), 8 deletions(-)

diff --git a/src/Interpreters/ActionsVisitor.cpp b/src/Interpreters/ActionsVisitor.cpp
index 54faf37f236..980207c7f9c 100644
--- a/src/Interpreters/ActionsVisitor.cpp
+++ b/src/Interpreters/ActionsVisitor.cpp
@@ -91,15 +91,35 @@ static size_t getTypeDepth(const DataTypePtr & type)
     return 0;
 }
 
+template <typename T>
+static bool decimalEqualsFloat(Field field, Float64 float_value)
+{
+    auto decimal_field = field.get<DecimalField<T>>();
+    auto decimal_to_float = DecimalUtils::convertTo<Float64>(decimal_field.getValue(), decimal_field.getScale());
+    return decimal_to_float == float_value;
+}
+
 /// Applies stricter rules than convertFieldToType:
 /// Doesn't allow :
-/// - loss of precision with `Decimals`
+/// - loss of precision converting to Decimal
 static bool convertFieldToTypeStrict(const Field & from_value, const IDataType & to_type, Field & result_value)
 {
     result_value = convertFieldToType(from_value, to_type);
     if (Field::isDecimal(from_value.getType()) && Field::isDecimal(result_value.getType()))
         return applyVisitor(FieldVisitorAccurateEquals{}, from_value, result_value);
-
+    if (from_value.getType() == Field::Types::Float64 && Field::isDecimal(result_value.getType()))
+    {
+        /// Convert back to Float64 and compare
+        if (result_value.getType() == Field::Types::Decimal32)
+            return decimalEqualsFloat<Decimal32>(result_value, from_value.get<Float64>());
+        if (result_value.getType() == Field::Types::Decimal64)
+            return decimalEqualsFloat<Decimal64>(result_value, from_value.get<Float64>());
+        if (result_value.getType() == Field::Types::Decimal128)
+            return decimalEqualsFloat<Decimal128>(result_value, from_value.get<Float64>());
+        if (result_value.getType() == Field::Types::Decimal256)
+            return decimalEqualsFloat<Decimal256>(result_value, from_value.get<Float64>());
+        throw Exception(ErrorCodes::LOGICAL_ERROR, "Unknown decimal type {}", result_value.getTypeName());
+    }
     return true;
 }
 
diff --git a/src/Interpreters/convertFieldToType.cpp b/src/Interpreters/convertFieldToType.cpp
index b6c72340472..55156cde7be 100644
--- a/src/Interpreters/convertFieldToType.cpp
+++ b/src/Interpreters/convertFieldToType.cpp
@@ -112,15 +112,16 @@ Field convertDecimalToDecimalType(const Field & from, const DataTypeDecimal<T> &
 template <typename From, typename T>
 Field convertFloatToDecimalType(const Field & from, const DataTypeDecimal<T> & type)
 {
-    From dValue = from.get<From>();
-    if (!type.canStoreWhole(dValue))
+    From value = from.get<From>();
+    if (!type.canStoreWhole(value))
         throw Exception("Number is too big to place in " + type.getName(), ErrorCodes::ARGUMENT_OUT_OF_BOUND);
 
-    String sValue = convertFieldToString(from);
-    int fromScale = sValue.length()- sValue.find('.') - 1;
+    //String sValue = convertFieldToString(from);
+    //int fromScale = sValue.length()- sValue.find('.') - 1;
+    UInt32 scale = type.getScale();
 
-    auto scaledValue = convertToDecimal<DataTypeNumber<From>, DataTypeDecimal<T>>(dValue, fromScale);
-    return DecimalField<T>(scaledValue, fromScale);
+    auto scaled_value = convertToDecimal<DataTypeNumber<From>, DataTypeDecimal<T>>(value, scale);
+    return DecimalField<T>(scaled_value, scale);
 }
 
 template <typename To>
diff --git a/tests/queries/0_stateless/02428_decimal_in_floating_point_literal.reference b/tests/queries/0_stateless/02428_decimal_in_floating_point_literal.reference
index 3c58c27aef9..378b7d8cec4 100644
--- a/tests/queries/0_stateless/02428_decimal_in_floating_point_literal.reference
+++ b/tests/queries/0_stateless/02428_decimal_in_floating_point_literal.reference
@@ -18,3 +18,4 @@
 1
 1
 1
+1