Method parseQueryFromMetadata

src/Databases/DatabaseOnDisk.cpp:699–762

}

ASTPtr DatabaseOnDisk::parseQueryFromMetadata(
    Poco::Logger * logger,
    ContextPtr local_context,
    const String & metadata_file_path,
    bool throw_on_error /*= true*/,
    bool remove_empty /*= false*/)
{
    String query;

    int metadata_file_fd = ::open(metadata_file_path.c_str(), O_RDONLY | O_CLOEXEC);

    if (metadata_file_fd == -1)
    {
        if (errno == ENOENT && !throw_on_error)
            return nullptr;

        throwFromErrnoWithPath("Cannot open file " + metadata_file_path, metadata_file_path,
                               errno == ENOENT ? ErrorCodes::FILE_DOESNT_EXIST : ErrorCodes::CANNOT_OPEN_FILE);
    }


    ReadBufferFromFile in(metadata_file_fd, metadata_file_path, METADATA_FILE_BUFFER_SIZE);
    readStringUntilEOF(query, in);

    /** Empty files with metadata are generated after a rough restart of the server.
      * Remove these files to slightly reduce the work of the admins on startup.
      */
    if (remove_empty && query.empty())
    {
        if (logger)
            LOG_ERROR(logger, "File {} is empty. Removing.", metadata_file_path);
        fs::remove(metadata_file_path);
        return nullptr;
    }

    auto settings = local_context->getSettingsRef();
    ParserCreateQuery parser(ParserSettings::valueOf(settings));
    const char * pos = query.data();
    std::string error_message;
    auto ast = tryParseQuery(parser, pos, pos + query.size(), error_message, /* hilite = */ false,
                             "in file " + metadata_file_path, /* allow_multi_statements = */ false, 0, settings.max_parser_depth);

    if (!ast && throw_on_error)
        throw Exception(error_message, ErrorCodes::SYNTAX_ERROR);
    else if (!ast)
        return nullptr;

    auto & create = ast->as<ASTCreateQuery &>();
    if (!create.table.empty() && create.uuid != UUIDHelpers::Nil)
    {
        String table_name = unescapeForFileName(fs::path(metadata_file_path).stem());

        if (create.table != TABLE_WITH_UUID_NAME_PLACEHOLDER && logger)
            LOG_WARNING(
                logger,
                "File {} contains both UUID and table name. Will use name `{}` instead of `{}`",
                metadata_file_path,
                table_name,