Change SHOW COLUMNS query to display MySQL types in MySQL Compatibility mode

src/Core/Settings.h

@@ -197,6 +197,7 @@ class IColumn;
     M(Bool, allow_experimental_inverted_index, false, "If it is set to true, allow to use experimental inverted index.", 0) \
     \
     M(UInt64, mysql_max_rows_to_insert, 65536, "The maximum number of rows in MySQL batch insertion of the MySQL storage engine", 0) \
+    M(Bool, use_mysql_types_in_show_columns, false, "Use MySQL converted types when connected via MySQL compatibility for show columns query", 0) \
     \
     M(UInt64, optimize_min_equality_disjunction_chain_length, 3, "The minimum length of the expression `expr = x1 OR ... expr = xN` for optimization ", 0) \
     \

src/DataTypes/DataTypeAggregateFunction.h

@@ -45,6 +45,7 @@ class DataTypeAggregateFunction final : public IDataType
     String doGetName() const override;
     String getNameWithoutVersion() const;
     const char * getFamilyName() const override { return "AggregateFunction"; }
+    String getSQLCompatibleName() const override { return "TEXT"; }
     TypeIndex getTypeId() const override { return TypeIndex::AggregateFunction; }
 
     Array getParameters() const { return parameters; }

src/DataTypes/DataTypeArray.h

@@ -30,6 +30,10 @@ class DataTypeArray final : public IDataType
     {
         return "Array";
     }
+    String getSQLCompatibleName() const override
+    {
+        return "TEXT";
+    }
 
     bool canBeInsideNullable() const override
     {

src/DataTypes/DataTypeDate.h

@@ -13,6 +13,7 @@ class DataTypeDate final : public DataTypeNumberBase<UInt16>
 
     TypeIndex getTypeId() const override { return TypeIndex::Date; }
     const char * getFamilyName() const override { return family_name; }
+    String getSQLCompatibleName() const override { return "DATE"; }
 
     bool canBeUsedAsVersion() const override { return true; }
     bool canBeInsideNullable() const override { return true; }

src/DataTypes/DataTypeDate32.h

@@ -13,6 +13,7 @@ class DataTypeDate32 final : public DataTypeNumberBase<Int32>
 
     TypeIndex getTypeId() const override { return TypeIndex::Date32; }
     const char * getFamilyName() const override { return family_name; }
+    String getSQLCompatibleName() const override { return "DATE"; }
 
     Field getDefault() const override
     {

src/DataTypes/DataTypeDateTime.h

@@ -36,6 +36,7 @@ class DataTypeDateTime final : public DataTypeNumberBase<UInt32>, public Timezon
     static constexpr auto family_name = "DateTime";
 
     const char * getFamilyName() const override { return family_name; }
+    String getSQLCompatibleName() const override { return "DATETIME"; }
     String doGetName() const override;
     TypeIndex getTypeId() const override { return TypeIndex::DateTime; }
 

src/DataTypes/DataTypeDateTime64.h

@@ -28,6 +28,7 @@ class DataTypeDateTime64 final : public DataTypeDecimalBase<DateTime64>, public
     DataTypeDateTime64(UInt32 scale_, const TimezoneMixin & time_zone_info);
 
     const char * getFamilyName() const override { return family_name; }
+    String getSQLCompatibleName() const override { return "DATETIME"; }
     std::string doGetName() const override;
     TypeIndex getTypeId() const override { return type_id; }
 

src/DataTypes/DataTypeEnum.cpp

@@ -36,6 +36,29 @@ const char * DataTypeEnum<Type>::getFamilyName() const
     return EnumName<FieldType>::value;
 }
 
+template <typename Type>
+std::string DataTypeEnum<Type>::generateMySQLName(const Values & values)
+{
+    WriteBufferFromOwnString out;
+
+    writeString("ENUM", out);
+    writeChar('(', out);
+
+    auto first = true;
+    for (const auto & name_and_value : values)
+    {
+        if (!first)
+            writeString(", ", out);
+
+        first = false;
+
+        writeQuotedString(name_and_value.first, out);
+    }
+
+    writeChar(')', out);
+
+    return out.str();
+}
 
 template <typename Type>
 std::string DataTypeEnum<Type>::generateName(const Values & values)

src/DataTypes/DataTypeEnum.h

@@ -46,12 +46,14 @@ class DataTypeEnum final : public IDataTypeEnum, public EnumValues<Type>
 private:
     std::string type_name;
     static std::string generateName(const Values & values);
+    static std::string generateMySQLName(const Values & values);
 
 public:
     explicit DataTypeEnum(const Values & values_);
 
     std::string doGetName() const override { return type_name; }
     const char * getFamilyName() const override;
+    String getSQLCompatibleName() const override { return generateMySQLName(this->getValues()); }
 
     TypeIndex getTypeId() const override { return type_id; }
 

src/DataTypes/DataTypeFixedString.h

@@ -42,6 +42,8 @@ class DataTypeFixedString final : public IDataType
     TypeIndex getTypeId() const override { return type_id; }
 
     const char * getFamilyName() const override { return "FixedString"; }
+    /// Use TEXT for compatibility with MySQL to allow arbitrary bytes.
+    String getSQLCompatibleName() const override { return "TEXT"; }
 
     size_t getN() const
     {

src/DataTypes/DataTypeFunction.h

@@ -24,6 +24,7 @@ class DataTypeFunction final : public IDataTypeDummy
 
     std::string doGetName() const override;
     const char * getFamilyName() const override { return "Function"; }
+    String getSQLCompatibleName() const override { return "TEXT"; }
     TypeIndex getTypeId() const override { return TypeIndex::Function; }
 
     const DataTypes & getArgumentTypes() const

src/DataTypes/DataTypeIPv4andIPv6.h

@@ -19,6 +19,8 @@ class DataTypeIPv4 : public IDataType
     static constexpr auto type_id = TypeToTypeIndex<IPv4>;
 
     const char * getFamilyName() const override { return TypeName<IPv4>.data(); }
+    String getSQLCompatibleName() const override { return "TEXT"; }
+
     TypeIndex getTypeId() const override { return type_id; }
 
     Field getDefault() const override { return IPv4{}; }
@@ -59,6 +61,8 @@ class DataTypeIPv6 : public IDataType
     static constexpr auto type_id = TypeToTypeIndex<IPv6>;
 
     const char * getFamilyName() const override { return TypeName<IPv6>.data(); }
+    String getSQLCompatibleName() const override { return "TEXT"; }
+
     TypeIndex getTypeId() const override { return type_id; }
 
     Field getDefault() const override { return IPv6{}; }

src/DataTypes/DataTypeInterval.h

@@ -26,6 +26,7 @@ class DataTypeInterval final : public DataTypeNumberBase<Int64>
 
     std::string doGetName() const override { return fmt::format("Interval{}", kind.toString()); }
     const char * getFamilyName() const override { return "Interval"; }
+    String getSQLCompatibleName() const override { return "TEXT"; }
     TypeIndex getTypeId() const override { return TypeIndex::Interval; }
 
     bool equals(const IDataType & rhs) const override;

src/DataTypes/DataTypeLowCardinality.h

@@ -12,6 +12,7 @@ class DataTypeLowCardinality : public IDataType
 private:
     DataTypePtr dictionary_type;
 
+
 public:
     explicit DataTypeLowCardinality(DataTypePtr dictionary_type_);
 
@@ -22,6 +23,8 @@ class DataTypeLowCardinality : public IDataType
         return "LowCardinality(" + dictionary_type->getName() + ")";
     }
     const char * getFamilyName() const override { return "LowCardinality"; }
+    String getSQLCompatibleName() const override { return dictionary_type->getSQLCompatibleName(); }
+
     TypeIndex getTypeId() const override { return TypeIndex::LowCardinality; }
 
     MutableColumnPtr createColumn() const override;

src/DataTypes/DataTypeMap.h

@@ -30,6 +30,7 @@ class DataTypeMap final : public IDataType
     TypeIndex getTypeId() const override { return TypeIndex::Map; }
     std::string doGetName() const override;
     const char * getFamilyName() const override { return "Map"; }
+    String getSQLCompatibleName() const override { return "JSON"; }
 
     bool canBeInsideNullable() const override { return false; }
 

src/DataTypes/DataTypeNothing.h

@@ -16,6 +16,8 @@ class DataTypeNothing final : public IDataTypeDummy
     static constexpr bool is_parametric = false;
 
     const char * getFamilyName() const override { return "Nothing"; }
+    String getSQLCompatibleName() const override { return "TEXT"; }
+
     TypeIndex getTypeId() const override { return TypeIndex::Nothing; }
 
     MutableColumnPtr createColumn() const override;

src/DataTypes/DataTypeNullable.h

@@ -16,6 +16,7 @@ class DataTypeNullable final : public IDataType
     explicit DataTypeNullable(const DataTypePtr & nested_data_type_);
     std::string doGetName() const override { return "Nullable(" + nested_data_type->getName() + ")"; }
     const char * getFamilyName() const override { return "Nullable"; }
+    String getSQLCompatibleName() const override { return nested_data_type->getSQLCompatibleName(); }
     TypeIndex getTypeId() const override { return TypeIndex::Nullable; }
 
     MutableColumnPtr createColumn() const override;

src/DataTypes/DataTypeNumberBase.cpp

@@ -11,6 +11,33 @@ Field DataTypeNumberBase<T>::getDefault() const
 {
     return NearestFieldType<FieldType>();
 }
+template <typename T>
+String DataTypeNumberBase<T>::getSQLCompatibleName() const
+{
+    if constexpr (std::is_same_v<T, Int8>)
+        return "TINYINT";
+    else if constexpr (std::is_same_v<T, Int16>)
+        return "SMALLINT";
+    else if constexpr (std::is_same_v<T, Int32>)
+        return "INTEGER";
+    else if constexpr (std::is_same_v<T, Int64>)
+        return "BIGINT";
+    else if constexpr (std::is_same_v<T, UInt8>)
+        return "TINYINT UNSIGNED";
+    else if constexpr (std::is_same_v<T, UInt16>)
+        return "SMALLINT UNSIGNED";
+    else if constexpr (std::is_same_v<T, UInt32>)
+        return "INTEGER UNSIGNED";
+    else if constexpr (std::is_same_v<T, UInt64>)
+        return "BIGINT UNSIGNED";
+    else if constexpr (std::is_same_v<T, Float32>)
+        return "FLOAT";
+    else if constexpr (std::is_same_v<T, Float64>)
+        return "DOUBLE";
+    /// Unsupported types are converted to TEXT
+    else
+        return "TEXT";
+}
 
 template <typename T>
 MutableColumnPtr DataTypeNumberBase<T>::createColumn() const
@@ -30,7 +57,6 @@ bool DataTypeNumberBase<T>::isValueRepresentedByUnsignedInteger() const
     return is_integer<T> && is_unsigned_v<T>;
 }
 
-
 /// Explicit template instantiations - to avoid code bloat in headers.
 template class DataTypeNumberBase<UInt8>;
 template class DataTypeNumberBase<UInt16>;

src/DataTypes/DataTypeNumberBase.h

@@ -25,6 +25,7 @@ class DataTypeNumberBase : public IDataType
     using ColumnType = ColumnVector<T>;
 
     const char * getFamilyName() const override { return TypeName<T>.data(); }
+    String getSQLCompatibleName() const override;
     TypeIndex getTypeId() const override { return TypeToTypeIndex<T>; }
 
     Field getDefault() const override;

src/DataTypes/DataTypeObject.h

@@ -23,6 +23,7 @@ class DataTypeObject : public IDataType
     DataTypeObject(const String & schema_format_, bool is_nullable_);
 
     const char * getFamilyName() const override { return "Object"; }
+    String getSQLCompatibleName() const override { return "JSON"; }
     String doGetName() const override;
     TypeIndex getTypeId() const override { return TypeIndex::Object; }
 

src/DataTypes/DataTypeSet.h

@@ -15,6 +15,8 @@ class DataTypeSet final : public IDataTypeDummy
 public:
     static constexpr bool is_parametric = true;
     const char * getFamilyName() const override { return "Set"; }
+    String getSQLCompatibleName() const override { return "TEXT"; }
+
     TypeIndex getTypeId() const override { return TypeIndex::Set; }
     bool equals(const IDataType & rhs) const override { return typeid(rhs) == typeid(*this); }
     bool isParametric() const override { return true; }

src/DataTypes/DataTypeString.h

@@ -21,6 +21,8 @@ class DataTypeString final : public IDataType
         return "String";
     }
 
+    String getSQLCompatibleName() const override { return "BLOB"; }
+
     TypeIndex getTypeId() const override { return type_id; }
 
     MutableColumnPtr createColumn() const override;

src/DataTypes/DataTypeTuple.h

@@ -33,6 +33,7 @@ class DataTypeTuple final : public IDataType
     TypeIndex getTypeId() const override { return TypeIndex::Tuple; }
     std::string doGetName() const override;
     const char * getFamilyName() const override { return "Tuple"; }
+    String getSQLCompatibleName() const override { return "JSON"; }
 
     bool canBeInsideNullable() const override { return false; }
     bool supportsSparseSerialization() const override { return true; }

src/DataTypes/DataTypeUUID.h

@@ -18,6 +18,8 @@ class DataTypeUUID : public IDataType
     static constexpr auto type_id = TypeIndex::UUID;
 
     const char * getFamilyName() const override { return "UUID"; }
+    String getSQLCompatibleName() const override { return "CHAR"; }
+
     TypeIndex getTypeId() const override { return type_id; }
 
     Field getDefault() const override;

src/DataTypes/DataTypesDecimal.cpp

@@ -28,6 +28,11 @@ std::string DataTypeDecimal<T>::doGetName() const
     return fmt::format("Decimal({}, {})", this->precision, this->scale);
 }
 
+template <is_decimal T>
+std::string DataTypeDecimal<T>::getSQLCompatibleName() const
+{
+    return fmt::format("DECIMAL({}, {})", this->precision, this->scale);
+}
 
 template <is_decimal T>
 bool DataTypeDecimal<T>::equals(const IDataType & rhs) const

src/DataTypes/DataTypesDecimal.h

@@ -39,6 +39,8 @@ class DataTypeDecimal final : public DataTypeDecimalBase<T>
     static constexpr auto family_name = "Decimal";
 
     const char * getFamilyName() const override { return family_name; }
+    String getSQLCompatibleName() const override;
+
     std::string doGetName() const override;
     TypeIndex getTypeId() const override { return TypeToTypeIndex<T>; }
     bool canBePromoted() const override { return true; }

src/DataTypes/IDataType.h

@@ -75,6 +75,8 @@ class IDataType : private boost::noncopyable, public std::enable_shared_from_thi
 
     /// Name of data type family (example: FixedString, Array).
     virtual const char * getFamilyName() const = 0;
+    /// Name of corresponding data type in MySQL (exampe: Bigint, Blob, etc)
+    virtual String getSQLCompatibleName() const = 0;
 
     /// Data type id. It's used for runtime type checks.
     virtual TypeIndex getTypeId() const = 0;

src/Storages/System/StorageSystemColumns.cpp

@@ -74,6 +74,8 @@ class ColumnsSource : public ISource
         : ISource(header_)
         , columns_mask(std::move(columns_mask_)), max_block_size(max_block_size_)
         , databases(std::move(databases_)), tables(std::move(tables_)), storages(std::move(storages_))
+        , client_info_interface(context->getClientInfo().interface)
+        , use_mysql_types(context->getSettingsRef().use_mysql_types_in_show_columns)
         , total_tables(tables->size()), access(context->getAccess())
         , query_id(context->getCurrentQueryId()), lock_acquire_timeout(context->getSettingsRef().lock_acquire_timeout)
     {
@@ -129,6 +131,18 @@ class ColumnsSource : public ISource
 
             bool check_access_for_columns = check_access_for_tables && !access->isGranted(AccessType::SHOW_COLUMNS, database_name, table_name);
 
+            auto get_type_name = [this](const IDataType& type) -> std::string
+            {
+                // Check if the use_mysql_types_in_show_columns setting is enabled and client is connected via MySQL protocol
+                if (use_mysql_types && client_info_interface == DB::ClientInfo::Interface::MYSQL)
+                {
+                    return type.getSQLCompatibleName();
+                }
+                else
+                {
+                    return type.getName();
+                }
+            };
             size_t position = 0;
             for (const auto & column : columns)
             {
@@ -146,7 +160,7 @@ class ColumnsSource : public ISource
                 if (columns_mask[src_index++])
                     res_columns[res_index++]->insert(column.name);
                 if (columns_mask[src_index++])
-                    res_columns[res_index++]->insert(column.type->getName());
+                    res_columns[res_index++]->insert(get_type_name(*column.type));
                 if (columns_mask[src_index++])
                     res_columns[res_index++]->insert(position);
 
@@ -281,6 +295,8 @@ class ColumnsSource : public ISource
     ColumnPtr databases;
     ColumnPtr tables;
     Storages storages;
+    ClientInfo::Interface client_info_interface;
+    bool use_mysql_types;
     size_t db_table_num = 0;
     size_t total_tables;
     std::shared_ptr<const ContextAccess> access;