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#include <Interpreters/RewriteOrderByVisitor.hpp>
#include <Parsers/ASTExpressionList.h>
#include <Parsers/ASTFunction.h>
#include <Parsers/ASTOrderByElement.h>
#include <Parsers/ASTSelectQuery.h>
namespace DB
{
void RewriteOrderBy::visit(ASTPtr & ast, Data &)
{
auto * query = ast->as<ASTSelectQuery>();
if (!query)
return;
const ASTPtr & order_by = query->orderBy();
if (!order_by)
return;
const auto * expr_list = order_by->as<ASTExpressionList>();
if (!expr_list)
return;
if (expr_list->children.size() != 1)
return;
const auto * order_by_elem = expr_list->children.front()->as<ASTOrderByElement>();
if (!order_by_elem)
return;
const auto * func = order_by_elem->children.front()->as<ASTFunction>();
if (!func || func->name != "tuple")
return;
if (const auto * inner_list = func->children.front()->as<ASTExpressionList>())
{
auto new_order_by = std::make_shared<ASTExpressionList>();
for (const auto & identifier : inner_list->children)
{
// clone w/o children
auto clone = std::make_shared<ASTOrderByElement>(*order_by_elem);
clone->children.clear();
clone->children.emplace_back(identifier);
new_order_by->children.emplace_back(clone);
}
if (!new_order_by->children.empty())
query->setExpression(ASTSelectQuery::Expression::ORDER_BY, std::move(new_order_by));
}
}
}
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