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Make function ifNull to allow to return non-Nullable result [#CLICKHOUSE-2789].

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This commit is contained in:
Alexey Milovidov 2017-03-09 21:58:44 +03:00
parent 19354bef87
commit 8da4e576a9
1 changed files with 24 additions and 12 deletions
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36
dbms/src/Functions/FunctionsNull.cpp
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@ -190,6 +190,15 @@ std::string FunctionIfNull::getName() const
return name;
}
static const DataTypePtr getNestedDataType(const DataTypePtr & type)
{
if (type->isNullable())
return static_cast<const DataTypeNullable &>(*type).getNestedType();
return type;
}
bool FunctionIfNull::hasSpecialSupportForNulls() const
{
return true;
@ -197,20 +206,29 @@ bool FunctionIfNull::hasSpecialSupportForNulls() const
DataTypePtr FunctionIfNull::getReturnTypeImpl(const DataTypes & arguments) const
{
return FunctionIf{}.getReturnTypeImpl({std::make_shared<DataTypeUInt8>(), arguments[0], arguments[1]});
if (arguments[0]->isNull())
return arguments[1];
return FunctionIf{}.getReturnTypeImpl({std::make_shared<DataTypeUInt8>(), getNestedDataType(arguments[0]), arguments[1]});
}
void FunctionIfNull::executeImpl(Block & block, const ColumnNumbers & arguments, size_t result)
{
/// ifNull(col1, col2) == multiIf(isNotNull(col1), col1, col2)
if (block.getByPosition(arguments[0]).column->isNull())
block.getByPosition(result).column = block.getByPosition(arguments[1]).column;
/// ifNull(col1, col2) == if(isNotNull(col1), assumeNotNull(col1), col2)
Block temp_block = block;
size_t res_pos = temp_block.columns();
size_t is_not_null_pos = temp_block.columns();
temp_block.insert({nullptr, std::make_shared<DataTypeUInt8>(), ""});
size_t assume_not_null_pos = temp_block.columns();
temp_block.insert({nullptr, getNestedDataType(block.getByPosition(arguments[0]).type), ""});
FunctionIsNotNull{}.executeImpl(temp_block, {arguments[0]}, res_pos);
FunctionIf{}.executeImpl(temp_block, {res_pos, arguments[0], arguments[1]}, result);
FunctionIsNotNull{}.executeImpl(temp_block, {arguments[0]}, is_not_null_pos);
FunctionAssumeNotNull{}.executeImpl(temp_block, {arguments[0]}, assume_not_null_pos);
FunctionIf{}.executeImpl(temp_block, {is_not_null_pos, assume_not_null_pos, arguments[1]}, result);
block.safeGetByPosition(result).column = std::move(temp_block.safeGetByPosition(result).column);
}
@ -285,13 +303,7 @@ DataTypePtr FunctionAssumeNotNull::getReturnTypeImpl(const DataTypes & arguments
{
if (arguments[0]->isNull())
throw Exception{"NULL is an invalid value for function " + getName(), ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT};
else if (arguments[0]->isNullable())
{
const DataTypeNullable & nullable_type = static_cast<const DataTypeNullable &>(*arguments[0]);
return nullable_type.getNestedType();
}
else
return arguments[0];
return getNestedDataType(arguments[0]);
}
void FunctionAssumeNotNull::executeImpl(Block & block, const ColumnNumbers & arguments, size_t result)