It hurts if server has millions of tables.

See https://github.com/ClickHouse/ClickHouse/pull/3398
Please add some tests to ensure it won't be broken in future.
#include <Databases/DatabaseOnDisk.h>
#include <IO/ReadBufferFromFile.h>
#include <IO/ReadHelpers.h>
#include <IO/WriteBufferFromFile.h>
#include <IO/WriteHelpers.h>
#include <Interpreters/Context.h>
#include <Interpreters/InterpreterCreateQuery.h>
#include <Parsers/ASTCreateQuery.h>
#include <Parsers/ParserCreateQuery.h>
#include <Parsers/formatAST.h>
#include <Parsers/parseQuery.h>
#include <Storages/IStorage.h>