Method getSortDescription

src/Interpreters/InterpreterSelectQuery.cpp:1469–1500

}

SortDescription InterpreterSelectQuery::getSortDescription(const ASTSelectQuery & query, const ContextPtr & context_)
{
    SortDescription order_descr;
    order_descr.reserve(query.orderBy()->children.size());

    for (const auto & elem : query.orderBy()->children)
    {
        const String & column_name = elem->children.front()->getColumnName();
        const auto & order_by_elem = elem->as<ASTOrderByElement &>();

        std::shared_ptr<Collator> collator;
        if (order_by_elem.getCollation())
            collator = std::make_shared<Collator>(order_by_elem.getCollation()->as<ASTLiteral &>().value.safeGet<String>());

        std::string alias;
        if (auto * identifier = order_by_elem.children[0]->as<ASTIdentifier>())
            alias = identifier->name();

        if (order_by_elem.with_fill)
        {
            FillColumnDescription fill_desc = getWithFillDescription(order_by_elem, context_);
            order_descr.emplace_back(alias, column_name, order_by_elem.direction, order_by_elem.nulls_direction, collator, true, fill_desc);
        }
        else
            order_descr.emplace_back(alias, column_name, order_by_elem.direction, order_by_elem.nulls_direction, collator);
    }

    order_descr.compile_sort_description = context_->getSettingsRef()[Setting::compile_sort_description];
    order_descr.min_count_to_compile_sort_description = context_->getSettingsRef()[Setting::min_count_to_compile_sort_description];

    return order_descr;
}

static InterpolateDescriptionPtr getInterpolateDescription(
    const ASTSelectQuery & query, const Block & source_block, const Block & result_block, const Aliases & aliases, ContextPtr context)