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#include <Analyzer/Passes/OptimizeRedundantFunctionsInOrderByPass.h>
#include <Functions/IFunction.h>
#include <Analyzer/ColumnNode.h>
#include <Analyzer/FunctionNode.h>
#include <Analyzer/HashUtils.h>
#include <Analyzer/InDepthQueryTreeVisitor.h>
#include <Analyzer/QueryNode.h>
#include <Analyzer/SortNode.h>
namespace DB
{
namespace
{
class OptimizeRedundantFunctionsInOrderByVisitor : public InDepthQueryTreeVisitorWithContext<OptimizeRedundantFunctionsInOrderByVisitor>
{
public:
using Base = InDepthQueryTreeVisitorWithContext<OptimizeRedundantFunctionsInOrderByVisitor>;
using Base::Base;
static bool needChildVisit(QueryTreeNodePtr & node, QueryTreeNodePtr & /*parent*/)
{
if (node->as<FunctionNode>())
return false;
return true;
}
void enterImpl(QueryTreeNodePtr & node)
{
if (!getSettings().optimize_redundant_functions_in_order_by)
return;
auto * query = node->as<QueryNode>();
if (!query)
return;
if (!query->hasOrderBy())
return;
auto & order_by = query->getOrderBy();
for (auto & elem : order_by.getNodes())
{
auto * order_by_elem = elem->as<SortNode>();
if (order_by_elem->withFill())
return;
}
QueryTreeNodes new_order_by_nodes;
new_order_by_nodes.reserve(order_by.getNodes().size());
for (auto & elem : order_by.getNodes())
{
auto & order_by_expr = elem->as<SortNode>()->getExpression();
switch (order_by_expr->getNodeType())
{
case QueryTreeNodeType::FUNCTION:
{
if (isRedundantExpression(order_by_expr))
continue;
break;
}
case QueryTreeNodeType::COLUMN:
{
existing_keys.insert(order_by_expr);
break;
}
default:
break;
}
new_order_by_nodes.push_back(elem);
}
existing_keys.clear();
if (new_order_by_nodes.size() < order_by.getNodes().size())
order_by.getNodes() = std::move(new_order_by_nodes);
}
private:
QueryTreeNodePtrWithHashSet existing_keys;
bool isRedundantExpression(QueryTreeNodePtr function)
{
QueryTreeNodes nodes_to_process{ function };
while (!nodes_to_process.empty())
{
auto node = nodes_to_process.back();
nodes_to_process.pop_back();
// TODO: handle constants here
switch (node->getNodeType())
{
case QueryTreeNodeType::FUNCTION:
{
auto * function_node = node->as<FunctionNode>();
const auto & function_arguments = function_node->getArguments().getNodes();
if (function_arguments.empty())
return false;
const auto & function_base = function_node->getFunction();
if (!function_base || !function_base->isDeterministicInScopeOfQuery())
return false;
// Process arguments in order
for (auto it = function_arguments.rbegin(); it != function_arguments.rend(); ++it)
nodes_to_process.push_back(*it);
break;
}
case QueryTreeNodeType::COLUMN:
{
if (!existing_keys.contains(node))
return false;
break;
}
default:
return false;
}
}
return true;
}
};
}
void OptimizeRedundantFunctionsInOrderByPass::run(QueryTreeNodePtr query_tree_node, ContextPtr context)
{
OptimizeRedundantFunctionsInOrderByVisitor visitor(std::move(context));
visitor.visit(query_tree_node);
}
}
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