ref #9436
Currently EPHEMERAL column requires an explicit default value provided on CREATE TABLE - we can allow implicit default there

throw Exception("MaterializedPostgreSQL is an experimental database engine. "
                        "Enable allow_experimental_database_materialized_postgresql to use it.", ErrorCodes::UNKNOWN_DATABASE_ENGINE);
    }
    DatabasePtr database = DatabaseFactory::get(create, metadata_path / "", getContext());
    if (create.uuid != UUIDHelpers::Nil)
        create.setDatabase(TABLE_WITH_UUID_NAME_PLACEHOLDER);
    bool need_write_metadata = !create.attach || !fs::exists(metadata_file_path);
    if (need_write_metadata)
    {
        create.attach = true;
        create.if_not_exists = false;
        WriteBufferFromOwnString statement_buf;
        formatAST(create, statement_buf, false);
        writeChar('\n', statement_buf);
        String statement = statement_buf.str();
        
        WriteBufferFromFile out(metadata_file_tmp_path, statement.size(), O_WRONLY | O_CREAT | O_EXCL);
        writeString(statement, out);
        out.next();
        if (getContext()->getSettingsRef().fsync_metadata)
            out.sync();
        out.close();
    }
    
    auto db_guard = DatabaseCatalog::instance().getExclusiveDDLGuardForDatabase(database_name);
    bool added = false;
    bool renamed = false;
    try
    {