Method beforeLoadingMetadata

src/Databases/DatabaseAtomic.cpp:536–565

}

void DatabaseAtomic::beforeLoadingMetadata(ContextMutablePtr /*context*/, LoadingStrictnessLevel mode)
{
    auto db_disk = getDisk();

    if (mode < LoadingStrictnessLevel::FORCE_RESTORE)
        return;

    if (!db_disk->isSymlinkSupported())
        return;

    // When `db_disk` is a `DiskLocal` object, `existsDirectory` will return false if the input path is a symlink.
    // So we use `existsFileOrDirectory` here to check if the symlink exists.
    if (!db_disk->existsFileOrDirectory(path_to_table_symlinks))
        return;

    /// Recreate symlinks to table data dirs in case of force restore, because some of them may be broken
    for (const auto it = db_disk->iterateDirectory(path_to_table_symlinks); it->isValid(); it->next())
    {
        auto table_path = fs::path(it->path());
        if (table_path.filename().empty())
            table_path = table_path.parent_path();
        if (!db_disk->isSymlink(table_path))
        {
            throw Exception(
                ErrorCodes::ABORTED, "'{}' is not a symlink. Atomic database should contains only symlinks.", std::string(table_path));
        }

        db_disk->removeFileIfExists(table_path);
    }
}

LoadTaskPtr DatabaseAtomic::startupDatabaseAsync(AsyncLoader & async_loader, LoadJobSet startup_after, LoadingStrictnessLevel mode)
{