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#include <Analyzer/Passes/LogicalExpressionOptimizerPass.h>
#include <Functions/FunctionFactory.h>
#include <Analyzer/InDepthQueryTreeVisitor.h>
#include <Analyzer/FunctionNode.h>
#include <Analyzer/ConstantNode.h>
#include <Analyzer/HashUtils.h>
namespace DB
{
class LogicalExpressionOptimizerVisitor : public InDepthQueryTreeVisitorWithContext<LogicalExpressionOptimizerVisitor>
{
public:
using Base = InDepthQueryTreeVisitorWithContext<LogicalExpressionOptimizerVisitor>;
explicit LogicalExpressionOptimizerVisitor(ContextPtr context)
: Base(std::move(context))
{}
void enterImpl(QueryTreeNodePtr & node)
{
auto * function_node = node->as<FunctionNode>();
if (!function_node)
return;
if (function_node->getFunctionName() == "or")
{
tryReplaceOrEqualsChainWithIn(node);
return;
}
if (function_node->getFunctionName() == "and")
{
tryReplaceAndEqualsChainsWithConstant(node);
return;
}
}
private:
void tryReplaceAndEqualsChainsWithConstant(QueryTreeNodePtr & node)
{
auto & function_node = node->as<FunctionNode &>();
assert(function_node.getFunctionName() == "and");
if (function_node.getResultType()->isNullable())
return;
QueryTreeNodes and_operands;
QueryTreeNodePtrWithHashMap<const ConstantNode *> node_to_constants;
for (const auto & argument : function_node.getArguments())
{
auto * argument_function = argument->as<FunctionNode>();
if (!argument_function || argument_function->getFunctionName() != "equals")
{
and_operands.push_back(argument);
continue;
}
const auto & equals_arguments = argument_function->getArguments().getNodes();
const auto & lhs = equals_arguments[0];
const auto & rhs = equals_arguments[1];
const auto has_and_with_different_constant = [&](const QueryTreeNodePtr & expression, const ConstantNode * constant)
{
if (auto it = node_to_constants.find(expression); it != node_to_constants.end())
{
if (!it->second->isEqual(*constant))
return true;
}
else
{
node_to_constants.emplace(expression, constant);
and_operands.push_back(argument);
}
return false;
};
bool collapse_to_false = false;
if (const auto * lhs_literal = lhs->as<ConstantNode>())
collapse_to_false = has_and_with_different_constant(rhs, lhs_literal);
else if (const auto * rhs_literal = rhs->as<ConstantNode>())
collapse_to_false = has_and_with_different_constant(lhs, rhs_literal);
else
and_operands.push_back(argument);
if (collapse_to_false)
{
auto false_value = std::make_shared<ConstantValue>(0u, function_node.getResultType());
auto false_node = std::make_shared<ConstantNode>(std::move(false_value));
node = std::move(false_node);
return;
}
}
if (and_operands.size() == function_node.getArguments().getNodes().size())
return;
if (and_operands.size() == 1)
{
/// AND operator can have UInt8 or bool as its type.
/// bool is used if a bool constant is at least one operand.
/// Because we reduce the number of operands here by eliminating the same equality checks,
/// the only situation we can end up here is we had AND check where all the equality checks are the same so we know the type is UInt8.
/// Otherwise, we will have > 1 operands and we don't have to do anything.
assert(!function_node.getResultType()->isNullable() && and_operands[0]->getResultType()->equals(*function_node.getResultType()));
node = std::move(and_operands[0]);
return;
}
auto and_function_resolver = FunctionFactory::instance().get("and", getContext());
function_node.getArguments().getNodes() = std::move(and_operands);
function_node.resolveAsFunction(and_function_resolver);
}
void tryReplaceOrEqualsChainWithIn(QueryTreeNodePtr & node)
{
auto & function_node = node->as<FunctionNode &>();
assert(function_node.getFunctionName() == "or");
QueryTreeNodes or_operands;
QueryTreeNodePtrWithHashMap<QueryTreeNodes> node_to_equals_functions;
QueryTreeNodePtrWithHashMap<QueryTreeNodeConstRawPtrWithHashSet> node_to_constants;
for (const auto & argument : function_node.getArguments())
{
auto * argument_function = argument->as<FunctionNode>();
if (!argument_function || argument_function->getFunctionName() != "equals")
{
or_operands.push_back(argument);
continue;
}
/// collect all equality checks (x = value)
const auto & equals_arguments = argument_function->getArguments().getNodes();
const auto & lhs = equals_arguments[0];
const auto & rhs = equals_arguments[1];
const auto add_equals_function_if_not_present = [&](const auto & expression_node, const ConstantNode * constant)
{
auto & constant_set = node_to_constants[expression_node];
if (!constant_set.contains(constant))
{
constant_set.insert(constant);
node_to_equals_functions[expression_node].push_back(argument);
}
};
if (const auto * lhs_literal = lhs->as<ConstantNode>();
lhs_literal && !lhs_literal->getValue().isNull())
add_equals_function_if_not_present(rhs, lhs_literal);
else if (const auto * rhs_literal = rhs->as<ConstantNode>();
rhs_literal && !rhs_literal->getValue().isNull())
add_equals_function_if_not_present(lhs, rhs_literal);
else
or_operands.push_back(argument);
}
auto in_function_resolver = FunctionFactory::instance().get("in", getContext());
for (auto & [expression, equals_functions] : node_to_equals_functions)
{
const auto & settings = getSettings();
if (equals_functions.size() < settings.optimize_min_equality_disjunction_chain_length && !expression.node->getResultType()->lowCardinality())
{
std::move(equals_functions.begin(), equals_functions.end(), std::back_inserter(or_operands));
continue;
}
Tuple args;
args.reserve(equals_functions.size());
/// first we create tuple from RHS of equals functions
for (const auto & equals : equals_functions)
{
const auto * equals_function = equals->as<FunctionNode>();
assert(equals_function && equals_function->getFunctionName() == "equals");
const auto & equals_arguments = equals_function->getArguments().getNodes();
if (const auto * rhs_literal = equals_arguments[1]->as<ConstantNode>())
{
args.push_back(rhs_literal->getValue());
}
else
{
const auto * lhs_literal = equals_arguments[0]->as<ConstantNode>();
assert(lhs_literal);
args.push_back(lhs_literal->getValue());
}
}
auto rhs_node = std::make_shared<ConstantNode>(std::move(args));
auto in_function = std::make_shared<FunctionNode>("in");
QueryTreeNodes in_arguments;
in_arguments.reserve(2);
in_arguments.push_back(expression.node);
in_arguments.push_back(std::move(rhs_node));
in_function->getArguments().getNodes() = std::move(in_arguments);
in_function->resolveAsFunction(in_function_resolver);
or_operands.push_back(std::move(in_function));
}
if (or_operands.size() == function_node.getArguments().getNodes().size())
return;
if (or_operands.size() == 1)
{
/// if the result type of operand is the same as the result type of OR
/// we can replace OR with the operand
if (or_operands[0]->getResultType()->equals(*function_node.getResultType()))
{
node = std::move(or_operands[0]);
return;
}
/// otherwise add a stub 0 to make OR correct
or_operands.push_back(std::make_shared<ConstantNode>(static_cast<UInt8>(0)));
}
auto or_function_resolver = FunctionFactory::instance().get("or", getContext());
function_node.getArguments().getNodes() = std::move(or_operands);
function_node.resolveAsFunction(or_function_resolver);
}
};
void LogicalExpressionOptimizerPass::run(QueryTreeNodePtr query_tree_node, ContextPtr context)
{
LogicalExpressionOptimizerVisitor visitor(std::move(context));
visitor.visit(query_tree_node);
}
}
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