Function getVirtualsForFileLikeStorage

src/Storages/VirtualColumnUtils.cpp:240–278

}

VirtualColumnsDescription getVirtualsForFileLikeStorage(
    ColumnsDescription & storage_columns,
    ContextPtr context,
    const std::optional<FormatSettings> & format_settings,
    std::optional<PartitionStrategyFactory::StrategyType> partition_strategy,
    const std::string & path)
{
    VirtualColumnsDescription desc;

    auto add_virtual = [&](const NameAndTypePair & pair)
    {
        const auto & name = pair.getNameInStorage();
        if (storage_columns.has(name))
            return;

        const auto & type = pair.getTypeInStorage();
        desc.addEphemeral(name, type, "", VirtualsMaterializationPlace::Reader);
    };

    for (const auto & item : getCommonVirtualsForFileLikeStorage())
        add_virtual(item);

    if (!path.empty())
    {
        if (!partition_strategy.has_value())
            throw Exception(ErrorCodes::LOGICAL_ERROR, "Expected partition strategy to be specified");

        /// If partition_stategy == none, we add hive columns, if present, to virtual columns.
        if (context->getSettingsRef()[Setting::use_hive_partitioning]
            && partition_strategy == PartitionStrategyFactory::StrategyType::NONE)
        {
            auto hive_columns = HivePartitioningUtils::extractHivePartitionColumnsFromPath(storage_columns, path, format_settings, context);
            for (const auto & column : hive_columns)
                add_virtual(column);
        }
    }

    return desc;
}

/// Appends one row to the already-detached mutable columns of `block`. The columns are detached once
/// by the caller (see `getFilterByPathAndFileIndexes`) so this per-row helper does not pay any