text: #if !defined(ARCADIA_BUILD)
  #include "config_core.h"
  #endif
  
  #if USE_MYSQL
  #include <Core/Defines.h>
  #include <Databases/MySQL/FetchTablesColumnsList.h>
  #include <DataTypes/DataTypeString.h>
  #include <DataTypes/DataTypesNumber.h>
  #include <DataTypes/convertMySQLDataType.h>
  #include <Formats/MySQLBlockInputStream.h>
  #include <IO/Operators.h>
  #include <Interpreters/Context.h>
  #include <Interpreters/evaluateConstantExpression.h>
  #include <Parsers/ASTFunction.h>
  #include <Parsers/ASTLiteral.h>
  #include <Storages/StorageMySQL.h>
  #include <TableFunctions/ITableFunction.h>
  #include <TableFunctions/TableFunctionFactory.h>
  #include <TableFunctions/TableFunctionMySQL.h>
  #include <Common/Exception.h>
  #include <Common/parseAddress.h>
  #include <Common/quoteString.h>
  #include "registerTableFunctions.h"
  
  #include <Databases/MySQL/DatabaseConnectionMySQL.h> // for fetchTablesColumnsList
  #include <Common/parseRemoteDescription.h>
  
  
  namespace DB
  {
  
  namespace ErrorCodes
  {
      extern const int LOGICAL_ERROR;
      extern const int NUMBER_OF_ARGUMENTS_DOESNT_MATCH;
      extern const int BAD_ARGUMENTS;
      extern const int UNKNOWN_TABLE;
  }
  
  void TableFunctionMySQL::parseArguments(const ASTPtr & ast_function, const Context & context)
  {
      const auto & args_func = ast_function->as<ASTFunction &>();
  
      if (!args_func.arguments)
          throw Exception("Table function 'mysql' must have arguments.", ErrorCodes::LOGICAL_ERROR);
  
      ASTs & args = args_func.arguments->children;
  
      if (args.size() < 5 || args.size() > 7)
          throw Exception("Table function 'mysql' requires 5-7 parameters: MySQL('host:port', database, table, 'user', 'password'[, replace_query, 'on_duplicate_clause']).",
              ErrorCodes::NUMBER_OF_ARGUMENTS_DOESNT_MATCH);
  
      for (auto & arg : args)
          arg = evaluateConstantExpressionOrIdentifierAsLiteral(arg, context);
  
      String host_port = args[0]->as<ASTLiteral &>().value.safeGet<String>();
      remote_database_name = args[1]->as<ASTLiteral &>().value.safeGet<String>();
      remote_table_name = args[2]->as<ASTLiteral &>().value.safeGet<String>();
      user_name = args[3]->as<ASTLiteral &>().value.safeGet<String>();
      password = args[4]->as<ASTLiteral &>().value.safeGet<String>();
  
      /// Split into replicas if needed. 3306 is the default MySQL port number
      size_t max_addresses = context.getSettingsRef().glob_expansion_max_elements;
      auto addresses = parseRemoteDescriptionForExternalDatabase(host_port, max_addresses, 3306);
      pool.emplace(remote_database_name, addresses, user_name, password);
  
      if (args.size() >= 6)
          replace_query = args[5]->as<ASTLiteral &>().value.safeGet<UInt64>() > 0;
      if (args.size() == 7)
          on_duplicate_clause = args[6]->as<ASTLiteral &>().value.safeGet<String>();
  
      if (replace_query && !on_duplicate_clause.empty())
          throw Exception(
              "Only one of 'replace_query' and 'on_duplicate_clause' can be specified, or none of them",
              ErrorCodes::BAD_ARGUMENTS);
  }
  
  ColumnsDescription TableFunctionMySQL::getActualTableStructure(const Context & context) const
  {
      const auto & settings = context.getSettingsRef();
      const auto tables_and_columns = fetchTablesColumnsList(*pool, remote_database_name, {remote_table_name}, settings.external_table_functions_use_nulls, settings.mysql_datatypes_support_level);
  
      const auto columns = tables_and_columns.find(remote_table_name);
      if (columns == tables_and_columns.end())
          throw Exception("MySQL table " + backQuoteIfNeed(remote_database_name) + "." + backQuoteIfNeed(remote_table_name) + " doesn't exist.", ErrorCodes::UNKNOWN_TABLE);
  
      return ColumnsDescription{columns->second};
  }
  
  StoragePtr TableFunctionMySQL::executeImpl(const ASTPtr & /*ast_function*/, const Context & context, const std::string & table_name, ColumnsDescription /*cached_columns*/) const
  {
      auto columns = getActualTableStructure(context);
  
      auto res = StorageMySQL::create(
          StorageID(getDatabaseName(), table_name),
          std::move(*pool),
          remote_database_name,
          remote_table_name,
          replace_query,
          on_duplicate_clause,
          columns,
          ConstraintsDescription{},
          context);
  
      pool.reset();
  
      res->startup();
      return res;
  }
  
  
  void registerTableFunctionMySQL(TableFunctionFactory & factory)
  {
      factory.registerFunction<TableFunctionMySQL>();
  }
  }
  
  #endif
  