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/**
* Copyright (C) 2022-present MongoDB, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the Server Side Public License, version 1,
* as published by MongoDB, Inc.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* Server Side Public License for more details.
*
* You should have received a copy of the Server Side Public License
* along with this program. If not, see
* <http://www.mongodb.com/licensing/server-side-public-license>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the Server Side Public License in all respects for
* all of the code used other than as permitted herein. If you modify file(s)
* with this exception, you may extend this exception to your version of the
* file(s), but you are not obligated to do so. If you do not wish to do so,
* delete this exception statement from your version. If you delete this
* exception statement from all source files in the program, then also delete
* it in the license file.
*/
#pragma once
#include <queue>
#include "mongo/db/query/optimizer/cascades/rewriter_rules.h"
#include "mongo/db/query/optimizer/node_defs.h"
namespace mongo::optimizer::cascades {
/**
* Represents a logical rewrite that will be attempted at a particular node, in a particular group.
*/
struct LogicalRewriteEntry {
LogicalRewriteEntry(double priority, LogicalRewriteType type, MemoLogicalNodeId nodeId);
LogicalRewriteEntry() = delete;
LogicalRewriteEntry(const LogicalRewriteEntry& other) = delete;
LogicalRewriteEntry(LogicalRewriteEntry&& other) = default;
// Numerically lower priority gets applied first.
double _priority;
LogicalRewriteType _type;
MemoLogicalNodeId _nodeId;
};
struct LogicalRewriteEntryComparator {
bool operator()(const std::unique_ptr<LogicalRewriteEntry>& x,
const std::unique_ptr<LogicalRewriteEntry>& y) const;
};
using LogicalRewriteQueue = std::priority_queue<std::unique_ptr<LogicalRewriteEntry>,
std::vector<std::unique_ptr<LogicalRewriteEntry>>,
LogicalRewriteEntryComparator>;
/**
* For now all physical rules use the same priority.
* TODO: use specific priorities (may depend on node parameters).
*/
static constexpr double kDefaultPriority = 10.0;
/**
* Keeps track of candidate physical rewrites.
*/
struct PhysRewriteEntry {
PhysRewriteEntry(double priority,
PhysicalRewriteType rule,
std::unique_ptr<ABT> node,
ChildPropsType childProps,
NodeCEMap nodeCEMap);
PhysRewriteEntry() = delete;
PhysRewriteEntry(const PhysRewriteEntry& other) = delete;
PhysRewriteEntry(PhysRewriteEntry&& other) = default;
// Numerically lower priority gets applied first.
double _priority;
// Rewrite rule that triggered this entry.
PhysicalRewriteType _rule;
// Node we are optimizing. This is typically a single node such as Filter with a
// MemoLogicalDelegator child, but could be a more complex tree.
std::unique_ptr<ABT> _node;
// For each child to optimize, we have associated physical properties. If we are optimizing the
// node under new properties (e.g. via enforcement) the map will contain a single entry using
// the address of the node itself (as opposed to the children to optimize).
ChildPropsType _childProps;
// Optional per-node CE. Used if the node is complex tree.
NodeCEMap _nodeCEMap;
};
struct PhysRewriteEntryComparator {
bool operator()(const std::unique_ptr<PhysRewriteEntry>& x,
const std::unique_ptr<PhysRewriteEntry>& y) const;
};
using PhysRewriteQueue = std::priority_queue<std::unique_ptr<PhysRewriteEntry>,
std::vector<std::unique_ptr<PhysRewriteEntry>>,
PhysRewriteEntryComparator>;
void optimizeChildrenNoAssert(PhysRewriteQueue& queue,
double priority,
PhysicalRewriteType rule,
std::unique_ptr<ABT> node,
ChildPropsType childProps,
NodeCEMap nodeCEMap);
void optimizeChildrenNoAssert(PhysRewriteQueue& queue,
double priority,
PhysicalRewriteType rule,
ABT node,
ChildPropsType childProps,
NodeCEMap nodeCEMap);
template <class T, PhysicalRewriteType rule>
static void optimizeChildren(PhysRewriteQueue& queue,
double priority,
ABT node,
ChildPropsType childProps) {
static_assert(canBePhysicalNode<T>(), "Can only optimize a physical node.");
optimizeChildrenNoAssert(
queue, priority, rule, std::move(node), std::move(childProps), {} /*nodeCEMap*/);
}
template <class T, PhysicalRewriteType rule>
static void optimizeChild(PhysRewriteQueue& queue,
double priority,
ABT node,
properties::PhysProps childProps) {
ABT& childRef = node.cast<T>()->getChild();
optimizeChildren<T, rule>(
queue, priority, std::move(node), ChildPropsType{{&childRef, std::move(childProps)}});
}
template <class T, PhysicalRewriteType rule>
static void optimizeChild(PhysRewriteQueue& queue, const double priority, ABT node) {
optimizeChildren<T, rule>(queue, priority, std::move(node), {} /*nodeCEMap*/);
}
template <PhysicalRewriteType rule>
void optimizeUnderNewProperties(cascades::PhysRewriteQueue& queue,
const double priority,
ABT child,
properties::PhysProps props) {
auto nodePtr = std::make_unique<ABT>(std::move(child));
ChildPropsType childProps{{nodePtr.get(), std::move(props)}};
optimizeChildrenNoAssert(
queue, priority, rule, std::move(nodePtr), std::move(childProps), {} /*nodeCEMap*/);
}
template <class T, PhysicalRewriteType rule>
static void optimizeChildren(PhysRewriteQueue& queue,
double priority,
ABT node,
properties::PhysProps leftProps,
properties::PhysProps rightProps) {
ABT& leftChildRef = node.cast<T>()->getLeftChild();
ABT& rightChildRef = node.cast<T>()->getRightChild();
optimizeChildren<T, rule>(
queue,
priority,
std::move(node),
{{&leftChildRef, std::move(leftProps)}, {&rightChildRef, std::move(rightProps)}});
}
} // namespace mongo::optimizer::cascades
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