The DataType instances are not shared when creating by TiDB::ColumnInfo

[JaySon-Huang]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

2. What did you expect to see? (Required)

3. What did you see instead (Required)

The way TiFlash handle newly create table is:

tiflash/dbms/src/TiDB/Schema/SchemaBuilder.cpp

Lines 1046 to 1072 in b25fa23

	std::tuple<NamesAndTypes, Strings> parseColumnsFromTableInfo(const TiDB::TableInfo & table_info)
	{
	NamesAndTypes columns;
	std::vector<String> primary_keys;
	for (const auto & column : table_info.columns)
	{
	DataTypePtr type = getDataTypeByColumnInfo(column);
	columns.emplace_back(column.name, type);
	if (column.hasPriKeyFlag())
	{
	primary_keys.emplace_back(column.name);
	}
	}
	if (!table_info.pk_is_handle)
	{
	// Make primary key as a column, and make the handle column as the primary key.
	if (table_info.is_common_handle)
	columns.emplace_back(MutSup::extra_handle_column_name, std::make_shared<DataTypeString>());
	else
	columns.emplace_back(MutSup::extra_handle_column_name, std::make_shared<DataTypeInt64>());
	primary_keys.clear();
	primary_keys.emplace_back(MutSup::extra_handle_column_name);
	}
	return std::make_tuple(std::move(columns), std::move(primary_keys));
	}

tiflash/dbms/src/TiDB/Decode/TypeMapping.cpp

Lines 202 to 214 in b25fa23

	// Get the data type according to column_info, respecting
	// the nullable flag.
	// This does not support the "duration" type.
	DataTypePtr getDataTypeByColumnInfo(const ColumnInfo & column_info)
	{
	DataTypePtr base = TypeMapping::instance().getDataType(column_info);
	if (!column_info.hasNotNullFlag())
	{
	return std::make_shared<DataTypeNullable>(base);
	}
	return base;
	}

tiflash/dbms/src/TiDB/Decode/TypeMapping.cpp

Lines 124 to 132 in b25fa23

	template <typename T>
	std::enable_if_t<
	!IsSignedType<T> && !IsDecimalType<T> && !IsEnumType<T> && !std::is_same_v<T, DataTypeMyDateTime>
	&& !IsArrayType<T>,
	DataTypePtr> //
	getDataTypeByColumnInfoBase(const ColumnInfo &, const T *)
	{
	return std::make_shared<T>();
	}

4. What is your TiFlash version? (Required)

nightly