Hawkin
/
arangodb
mirror of https://gitee.com/bigwinds/arangodb
1
0
Fork 0
Code Issues Projects Releases Wiki Activity
arangodb/arangod/Aql/OptimizerRules.cpp

1242 lines
42 KiB
C++
Raw Blame History

////////////////////////////////////////////////////////////////////////////////
/// @brief rules for the query optimizer
///
/// @file arangod/Aql/OptimizerRules.cpp
///
/// DISCLAIMER
///
/// Copyright 2010-2014 triagens GmbH, Cologne, Germany
///
/// Licensed under the Apache License, Version 2.0 (the "License");
/// you may not use this file except in compliance with the License.
/// You may obtain a copy of the License at
///
/// http://www.apache.org/licenses/LICENSE-2.0
///
/// Unless required by applicable law or agreed to in writing, software
/// distributed under the License is distributed on an "AS IS" BASIS,
/// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
/// See the License for the specific language governing permissions and
/// limitations under the License.
///
/// Copyright holder is triAGENS GmbH, Cologne, Germany
///
/// @author Max Neunhoeffer
/// @author Copyright 2014, triagens GmbH, Cologne, Germany
////////////////////////////////////////////////////////////////////////////////
#include "Aql/OptimizerRules.h"
#include "Aql/ExecutionNode.h"
#include "Aql/Indexes.h"
#include "Aql/Variable.h"
using namespace triagens::aql;
using Json = triagens::basics::Json;
using EN = triagens::aql::ExecutionNode;
// -----------------------------------------------------------------------------
// --SECTION-- rules for the optimizer
// -----------------------------------------------------------------------------
////////////////////////////////////////////////////////////////////////////////
/// @brief remove redundant sorts
/// this rule modifies the plan in place:
/// - sorts that are covered by earlier sorts will be removed
////////////////////////////////////////////////////////////////////////////////
int triagens::aql::removeRedundantSorts (Optimizer* opt,
ExecutionPlan* plan,
Optimizer::Rule const* rule) {
std::vector<ExecutionNode*> nodes = plan->findNodesOfType(triagens::aql::ExecutionNode::SORT, true);
std::unordered_set<ExecutionNode*> toUnlink;
for (auto n : nodes) {
if (toUnlink.find(n) != toUnlink.end()) {
// encountered a sort node that we already deleted
continue;
}
auto const sortNode = static_cast<SortNode*>(n);
auto sortInfo = sortNode->getSortInformation(plan);
if (sortInfo.isValid && ! sortInfo.criteria.empty()) {
// we found a sort that we can understand
std::vector<ExecutionNode*> stack;
for (auto dep : sortNode->getDependencies()) {
stack.push_back(dep);
}
int nodesRelyingOnSort = 0;
while (! stack.empty()) {
auto current = stack.back();
stack.pop_back();
if (current->getType() == triagens::aql::ExecutionNode::SORT) {
// we found another sort. now check if they are compatible!
auto other = static_cast<SortNode*>(current)->getSortInformation(plan);
switch (sortInfo.isCoveredBy(other)) {
case SortInformation::unequal: {
// different sort criteria
if (nodesRelyingOnSort == 0) {
// a sort directly followed by another sort: now remove one of them
if (other.canThrow) {
// if the sort can throw, we must not remove it
break;
}
if (sortNode->isStable()) {
// we should not optimize predecessors of a stable sort (used in a COLLECT node)
// the stable sort is for a reason, and removing any predecessors sorts might
// change the result
break;
}
// remove sort that is a direct predecessor of a sort
toUnlink.insert(current);
}
break;
}
case SortInformation::otherLessAccurate: {
toUnlink.insert(current);
break;
}
case SortInformation::ourselvesLessAccurate: {
// the sort at the start of the pipeline makes the sort at the end
// superfluous, so we'll remove it
toUnlink.insert(n);
break;
}
case SortInformation::allEqual: {
// the sort at the end of the pipeline makes the sort at the start
// superfluous, so we'll remove it
toUnlink.insert(current);
break;
}
}
}
else if (current->getType() == triagens::aql::ExecutionNode::FILTER) {
// ok: a filter does not depend on sort order
}
else if (current->getType() == triagens::aql::ExecutionNode::CALCULATION) {
// ok: a filter does not depend on sort order only if it does not throw
if (current->canThrow()) {
++nodesRelyingOnSort;
}
}
else if (current->getType() == triagens::aql::ExecutionNode::ENUMERATE_LIST ||
current->getType() == triagens::aql::ExecutionNode::ENUMERATE_COLLECTION) {
// ok, but we cannot remove two different sorts if one of these node types is between them
// example: in the following query, the one sort will be optimized away:
// FOR i IN [ { a: 1 }, { a: 2 } , { a: 3 } ] SORT i.a ASC SORT i.a DESC RETURN i
// but in the following query, the sorts will stay:
// FOR i IN [ { a: 1 }, { a: 2 } , { a: 3 } ] SORT i.a ASC LET a = i.a SORT i.a DESC RETURN i
++nodesRelyingOnSort;
}
else {
// abort at all other type of nodes. we cannot remove a sort beyond them
// this include COLLECT and LIMIT
break;
}
auto deps = current->getDependencies();
if (deps.size() != 1) {
// node either has no or more than one dependency. we don't know what to do and must abort
// note: this will also handle Singleton nodes
break;
}
for (auto dep : deps) {
stack.push_back(dep);
}
}
}
}
if (! toUnlink.empty()) {
plan->unlinkNodes(toUnlink);
plan->findVarUsage();
}
opt->addPlan(plan, rule->level, ! toUnlink.empty());
return TRI_ERROR_NO_ERROR;
}
////////////////////////////////////////////////////////////////////////////////
/// @brief remove all unnecessary filters
/// this rule modifies the plan in place:
/// - filters that are always true are removed completely
/// - filters that are always false will be replaced by a NoResults node
////////////////////////////////////////////////////////////////////////////////
int triagens::aql::removeUnnecessaryFiltersRule (Optimizer* opt,
ExecutionPlan* plan,
Optimizer::Rule const* rule) {
bool modified = false;
std::unordered_set<ExecutionNode*> toUnlink;
// should we enter subqueries??
std::vector<ExecutionNode*> nodes = plan->findNodesOfType(triagens::aql::ExecutionNode::FILTER, true);
for (auto n : nodes) {
// filter nodes always have one input variable
auto varsUsedHere = n->getVariablesUsedHere();
TRI_ASSERT(varsUsedHere.size() == 1);
// now check who introduced our variable
auto variable = varsUsedHere[0];
auto setter = plan->getVarSetBy(variable->id);
if (setter == nullptr ||
setter->getType() != triagens::aql::ExecutionNode::CALCULATION) {
// filter variable was not introduced by a calculation.
continue;
}
// filter variable was introduced a CalculationNode. now check the expression
auto s = static_cast<CalculationNode*>(setter);
auto root = s->expression()->node();
if (! root->isConstant()) {
// filter expression can only be evaluated at runtime
continue;
}
// filter expression is constant and thus cannot throw
// we can now evaluate it safely
TRI_ASSERT(! s->expression()->canThrow());
if (root->toBoolean()) {
// filter is always true
// remove filter node and merge with following node
toUnlink.insert(n);
modified = true;
}
else {
// filter is always false
// now insert a NoResults node below it
auto noResults = new NoResultsNode(plan->nextId());
plan->registerNode(noResults);
plan->replaceNode(n, noResults);
modified = true;
}
}
if (! toUnlink.empty()) {
plan->unlinkNodes(toUnlink);
plan->findVarUsage();
}
opt->addPlan(plan, rule->level, modified);
return TRI_ERROR_NO_ERROR;
}
////////////////////////////////////////////////////////////////////////////////
/// @brief move calculations up in the plan
/// this rule modifies the plan in place
/// it aims to move up calculations as far up in the plan as possible, to
/// avoid redundant calculations in inner loops
////////////////////////////////////////////////////////////////////////////////
int triagens::aql::moveCalculationsUpRule (Optimizer* opt,
ExecutionPlan* plan,
Optimizer::Rule const* rule) {
std::vector<ExecutionNode*> nodes = plan->findNodesOfType(triagens::aql::ExecutionNode::CALCULATION, true);
bool modified = false;
for (auto n : nodes) {
auto nn = static_cast<CalculationNode*>(n);
if (nn->expression()->canThrow()) {
// we will only move expressions up that cannot throw
continue;
}
auto const neededVars = n->getVariablesUsedHere();
std::vector<ExecutionNode*> stack;
for (auto dep : n->getDependencies()) {
stack.push_back(dep);
}
while (! stack.empty()) {
auto current = stack.back();
stack.pop_back();
bool found = false;
auto&& varsSet = current->getVariablesSetHere();
for (auto v : varsSet) {
for (auto it = neededVars.begin(); it != neededVars.end(); ++it) {
if ((*it)->id == v->id) {
// shared variable, cannot move up any more
found = true;
break;
}
}
}
if (found) {
// done with optimizing this calculation node
break;
}
auto deps = current->getDependencies();
if (deps.size() != 1) {
// node either has no or more than one dependency. we don't know what to do and must abort
// note: this will also handle Singleton nodes
break;
}
for (auto dep : deps) {
stack.push_back(dep);
}
// first, unlink the calculation from the plan
plan->unlinkNode(n);
// and re-insert into before the current node
plan->insertDependency(current, n);
modified = true;
}
}
if (modified) {
plan->findVarUsage();
}
opt->addPlan(plan, rule->level, modified);
return TRI_ERROR_NO_ERROR;
}
////////////////////////////////////////////////////////////////////////////////
/// @brief move filters up in the plan
/// this rule modifies the plan in place
/// filters are moved as far up in the plan as possible to make result sets
/// as small as possible as early as possible
/// filters are not pushed beyond limits
////////////////////////////////////////////////////////////////////////////////
int triagens::aql::moveFiltersUpRule (Optimizer* opt,
ExecutionPlan* plan,
Optimizer::Rule const* rule) {
std::vector<ExecutionNode*> nodes = plan->findNodesOfType(triagens::aql::ExecutionNode::FILTER, true);
bool modified = false;
for (auto n : nodes) {
auto neededVars = n->getVariablesUsedHere();
TRI_ASSERT(neededVars.size() == 1);
std::vector<ExecutionNode*> stack;
for (auto dep : n->getDependencies()) {
stack.push_back(dep);
}
while (! stack.empty()) {
auto current = stack.back();
stack.pop_back();
if (current->getType() == triagens::aql::ExecutionNode::LIMIT) {
// cannot push a filter beyond a LIMIT node
break;
}
bool found = false;
auto&& varsSet = current->getVariablesSetHere();
for (auto v : varsSet) {
for (auto it = neededVars.begin(); it != neededVars.end(); ++it) {
if ((*it)->id == v->id) {
// shared variable, cannot move up any more
found = true;
break;
}
}
}
if (found) {
// done with optimizing this calculation node
break;
}
auto deps = current->getDependencies();
if (deps.size() != 1) {
// node either has no or more than one dependency. we don't know what to do and must abort
// note: this will also handle Singleton nodes
break;
}
for (auto dep : deps) {
stack.push_back(dep);
}
// first, unlink the filter from the plan
plan->unlinkNode(n);
// and re-insert into plan in front of the current node
plan->insertDependency(current, n);
modified = true;
}
}
if (modified) {
plan->findVarUsage();
}
opt->addPlan(plan, rule->level, modified);
return TRI_ERROR_NO_ERROR;
}
////////////////////////////////////////////////////////////////////////////////
/// @brief remove CalculationNode(s) that are never needed
/// this modifies an existing plan in place
////////////////////////////////////////////////////////////////////////////////
int triagens::aql::removeUnnecessaryCalculationsRule (Optimizer* opt,
ExecutionPlan* plan,
Optimizer::Rule const* rule) {
std::vector<ExecutionNode*> nodes
= plan->findNodesOfType(triagens::aql::ExecutionNode::CALCULATION, true);
std::unordered_set<ExecutionNode*> toUnlink;
for (auto n : nodes) {
auto nn = static_cast<CalculationNode*>(n);
if (nn->expression()->canThrow() ||
! nn->expression()->isDeterministic()) {
// If this node can throw or is non-deterministic, we must not optimize it away!
continue;
}
auto outvar = n->getVariablesSetHere();
TRI_ASSERT(outvar.size() == 1);
auto varsUsedLater = n->getVarsUsedLater();
if (varsUsedLater.find(outvar[0]) == varsUsedLater.end()) {
// The variable whose value is calculated here is not used at
// all further down the pipeline! We remove the whole
// calculation node,
toUnlink.insert(n);
}
}
if (! toUnlink.empty()) {
plan->unlinkNodes(toUnlink);
plan->findVarUsage();
}
opt->addPlan(plan, rule->level, ! toUnlink.empty());
return TRI_ERROR_NO_ERROR;
}
////////////////////////////////////////////////////////////////////////////////
/// @brief prefer IndexRange nodes over EnumerateCollection nodes
////////////////////////////////////////////////////////////////////////////////
class FilterToEnumCollFinder : public WalkerWorker<ExecutionNode> {
RangesInfo* _ranges;
Optimizer* _opt;
ExecutionPlan* _plan;
std::unordered_set<VariableId> _varIds;
bool _canThrow;
Optimizer::RuleLevel _level;
public:
FilterToEnumCollFinder (Optimizer* opt,
ExecutionPlan* plan,
Variable const* var,
Optimizer::RuleLevel level)
: _opt(opt),
_plan(plan),
_canThrow(false),
_level(level) {
_ranges = new RangesInfo();
_varIds.insert(var->id);
};
~FilterToEnumCollFinder () {
delete _ranges;
}
bool before (ExecutionNode* en) {
_canThrow = (_canThrow || en->canThrow()); // can any node walked over throw?
switch (en->getType()) {
case EN::ENUMERATE_LIST:
break;
case EN::CALCULATION: {
auto outvar = en->getVariablesSetHere();
TRI_ASSERT(outvar.size() == 1);
if (_varIds.find(outvar[0]->id) != _varIds.end()) {
auto node = static_cast<CalculationNode*>(en);
std::string attr;
std::string enumCollVar;
buildRangeInfo(node->expression()->node(), enumCollVar, attr);
}
break;
}
case EN::SUBQUERY:
break;
case EN::FILTER:{
std::vector<Variable const*> inVar = en->getVariablesUsedHere();
TRI_ASSERT(inVar.size() == 1);
_varIds.insert(inVar[0]->id);
break;
}
case EN::INTERSECTION:
case EN::AGGREGATE:
case EN::LOOKUP_JOIN:
case EN::MERGE_JOIN:
case EN::LOOKUP_INDEX_UNIQUE:
case EN::LOOKUP_INDEX_RANGE:
case EN::LOOKUP_FULL_COLLECTION:
case EN::CONCATENATION:
case EN::MERGE:
case EN::REMOTE:
// in these cases we simply ignore the intermediate nodes, note
// that we have taken care of nodes that could throw exceptions
// above.
break;
case EN::SINGLETON:
case EN::INSERT:
case EN::REMOVE:
case EN::REPLACE:
case EN::UPDATE:
case EN::RETURN:
case EN::NORESULTS:
case EN::ILLEGAL:
// in all these cases something is seriously wrong and we better abort
return true;
case EN::LIMIT:
// if we meet a limit node between a filter and an enumerate
// collection, we abort . . .
return true;
case EN::SORT:
case EN::INDEX_RANGE:
break;
case EN::ENUMERATE_COLLECTION:{
auto node = static_cast<EnumerateCollectionNode*>(en);
auto var = node->getVariablesSetHere()[0]; // should only be 1
auto map = _ranges->find(var->name); // check if we have any ranges with this var
if (map != nullptr) {
// check the first components of <map> against indexes of <node>...
std::unordered_set<std::string> attrs;
bool valid = true; // are all the range infos valid?
for(auto x: *map) {
valid &= x.second.isValid();
if (!valid) {
break;
}
attrs.insert(x.first);
}
if (! _canThrow) {
if (! valid) { // ranges are not valid . . .
auto newPlan = _plan->clone();
try {
auto parents = newPlan->getNodeById(node->id())->getParents();
for (auto x: parents) {
auto noRes = new NoResultsNode(newPlan->nextId());
newPlan->registerNode(noRes);
newPlan->insertDependency(x, noRes);
_opt->addPlan(newPlan, _level, true);
}
}
catch (...) {
delete newPlan;
throw;
}
}
else {
std::vector<TRI_index_t*> idxs;
std::vector<size_t> prefixes;
// {idxs.at(i)->_fields[0]..idxs.at(i)->_fields[prefixes.at(i)]}
// is a subset of <attrs>
// note: prefixes are only used for skiplist indexes
// for all other index types, the prefix value will always be 0
node->getIndexesForIndexRangeNode(attrs, idxs, prefixes);
// make one new plan for every index in <idxs> that replaces the
// enumerate collection node with a IndexRangeNode ...
for (size_t i = 0; i < idxs.size(); i++) {
std::vector<std::vector<RangeInfo>> rangeInfo;
rangeInfo.push_back(std::vector<RangeInfo>());
// ranges must be valid and all comparisons == if hash index or ==
// followed by a single <, >, >=, or <= if a skip index in the
// order of the fields of the index.
auto idx = idxs.at(i);
if (idx->_type == TRI_IDX_TYPE_HASH_INDEX ||
idx->_type == TRI_IDX_TYPE_PRIMARY_INDEX) {
for (size_t j = 0; j < idx->_fields._length; j++) {
auto range = map->find(std::string(idx->_fields._buffer[j]));
if (! range->second.is1ValueRangeInfo()) {
rangeInfo.at(0).clear(); // not usable
break;
}
rangeInfo.at(0).push_back(range->second);
}
}
else if (idx->_type == TRI_IDX_TYPE_EDGE_INDEX) {
for (size_t j = 0; j < idx->_fields._length; j++) {
auto range = map->find(std::string(idx->_fields._buffer[j]));
if (range == map->end()) {
continue;
}
if (! range->second.is1ValueRangeInfo()) {
rangeInfo.at(0).clear(); // not usable
break;
}
rangeInfo.at(0).push_back(range->second);
}
}
else if (idx->_type == TRI_IDX_TYPE_SKIPLIST_INDEX) {
size_t j = 0;
auto range = map->find(std::string(idx->_fields._buffer[0]));
rangeInfo.at(0).push_back(range->second);
bool equality = range->second.is1ValueRangeInfo();
while (++j < prefixes.at(i) && equality) {
range = map->find(std::string(idx->_fields._buffer[j]));
rangeInfo.at(0).push_back(range->second);
equality = equality && range->second.is1ValueRangeInfo();
}
}
if (! rangeInfo.at(0).empty()) {
auto newPlan = _plan->clone();
try {
ExecutionNode* newNode = new IndexRangeNode(newPlan->nextId(), node->vocbase(),
node->collection(), node->outVariable(), idx, rangeInfo);
newPlan->registerNode(newNode);
newPlan->replaceNode(newPlan->getNodeById(node->id()), newNode);
_opt->addPlan(newPlan, _level, true);
}
catch (...) {
delete newPlan;
throw;
}
}
}
}
}
}
break;
}
}
return false;
}
void buildRangeInfo (AstNode const* node, std::string& enumCollVar, std::string& attr) {
if (node->type == NODE_TYPE_REFERENCE) {
auto x = static_cast<Variable*>(node->getData());
auto setter = _plan->getVarSetBy(x->id);
if (setter != nullptr &&
setter->getType() == triagens::aql::ExecutionNode::ENUMERATE_COLLECTION) {
enumCollVar = x->name;
}
return;
}
if (node->type == NODE_TYPE_ATTRIBUTE_ACCESS) {
char const* attributeName = node->getStringValue();
buildRangeInfo(node->getMember(0), enumCollVar, attr);
if (! enumCollVar.empty()) {
attr.append(attributeName);
attr.push_back('.');
}
return;
}
if (node->type == NODE_TYPE_OPERATOR_BINARY_EQ) {
auto lhs = node->getMember(0);
auto rhs = node->getMember(1);
bool found = false;
AstNode const* val = nullptr;
if(rhs->type == NODE_TYPE_ATTRIBUTE_ACCESS) {
buildRangeInfo(rhs, enumCollVar, attr);
if (! enumCollVar.empty()) {
// Found a multiple attribute access of a variable
if (lhs->type == NODE_TYPE_VALUE) {
val = lhs;
found = true;
}
else {
enumCollVar.clear();
}
}
}
if (! found && lhs->type == NODE_TYPE_ATTRIBUTE_ACCESS) {
buildRangeInfo(lhs, enumCollVar, attr);
if (! enumCollVar.empty()) {
// Found a multiple attribute access of a variable
if (rhs->type == NODE_TYPE_VALUE) {
val = rhs;
found = true;
}
else {
enumCollVar.clear();
}
}
}
if (found) {
_ranges->insert(enumCollVar, attr.substr(0, attr.size() - 1),
RangeInfoBound(val, true), RangeInfoBound(val, true), true);
}
attr.clear();
enumCollVar.clear();
return;
}
if(node->type == NODE_TYPE_OPERATOR_BINARY_LT ||
node->type == NODE_TYPE_OPERATOR_BINARY_GT ||
node->type == NODE_TYPE_OPERATOR_BINARY_LE ||
node->type == NODE_TYPE_OPERATOR_BINARY_GE) {
bool include = (node->type == NODE_TYPE_OPERATOR_BINARY_LE ||
node->type == NODE_TYPE_OPERATOR_BINARY_GE);
auto lhs = node->getMember(0);
auto rhs = node->getMember(1);
RangeInfoBound low;
RangeInfoBound high;
if (rhs->type == NODE_TYPE_ATTRIBUTE_ACCESS) {
// Attribute access on the right:
// First find out whether there is a multiple attribute access
// of a variable on the right:
buildRangeInfo(rhs, enumCollVar, attr);
if (! enumCollVar.empty()) {
// Constant value on the left, so insert a constant condition:
if (node->type == NODE_TYPE_OPERATOR_BINARY_GE ||
node->type == NODE_TYPE_OPERATOR_BINARY_GT) {
high.assign(lhs, include);
}
else {
low.assign(lhs, include);
}
_ranges->insert(enumCollVar, attr.substr(0, attr.size()-1),
low, high, false);
}
}
else if (lhs->type == NODE_TYPE_ATTRIBUTE_ACCESS) {
// Attribute access on the left:
// First find out whether there is a multiple attribute access
// of a variable on the left:
buildRangeInfo(lhs, enumCollVar, attr);
if (! enumCollVar.empty()) {
// Constant value on the right, so insert a constant condition:
if (node->type == NODE_TYPE_OPERATOR_BINARY_GE ||
node->type == NODE_TYPE_OPERATOR_BINARY_GT) {
low.assign(rhs, include);
}
else {
high.assign(rhs, include);
}
_ranges->insert(enumCollVar, attr.substr(0, attr.size()-1),
low, high, false);
}
}
}
if (node->type == NODE_TYPE_OPERATOR_BINARY_AND) {
buildRangeInfo(node->getMember(0), enumCollVar, attr);
buildRangeInfo(node->getMember(1), enumCollVar, attr);
}
/* TODO: or isn't implemented yet.
if (node->type == NODE_TYPE_OPERATOR_BINARY_OR) {
buildRangeInfo(node->getMember(0), enumCollVar, attr);
buildRangeInfo(node->getMember(1), enumCollVar, attr);
}
*/
attr = "";
enumCollVar = "";
return;
}
};
////////////////////////////////////////////////////////////////////////////////
/// @brief useIndexRange, try to use an index for filtering
////////////////////////////////////////////////////////////////////////////////
int triagens::aql::useIndexRange (Optimizer* opt,
ExecutionPlan* plan,
Optimizer::Rule const* rule) {
std::vector<ExecutionNode*> nodes
= plan->findNodesOfType(triagens::aql::ExecutionNode::FILTER, true);
for (auto n : nodes) {
auto nn = static_cast<FilterNode*>(n);
auto invars = nn->getVariablesUsedHere();
TRI_ASSERT(invars.size() == 1);
FilterToEnumCollFinder finder(opt, plan, invars[0], rule->level);
nn->walk(&finder);
}
opt->addPlan(plan, rule->level, false);
return TRI_ERROR_NO_ERROR;
}
////////////////////////////////////////////////////////////////////////////////
/// @brief analyse the sortnode and its calculation nodes
////////////////////////////////////////////////////////////////////////////////
class SortAnalysis {
using ECN = triagens::aql::EnumerateCollectionNode;
typedef std::pair<ECN::IndexMatchVec, IndexOrCondition> Range_IndexPair;
struct sortNodeData {
bool ASC;
size_t calculationNodeID;
std::string variableName;
std::string attributevec;
};
std::vector<sortNodeData*> _sortNodeData;
public:
size_t const sortNodeID;
////////////////////////////////////////////////////////////////////////////////
/// @brief constructor; fetches the referenced calculation nodes and builds
/// _sortNodeData for later use.
////////////////////////////////////////////////////////////////////////////////
SortAnalysis (SortNode* node)
: sortNodeID(node->id())
{
auto sortParams = node->getCalcNodePairs();
for (size_t n = 0; n < sortParams.size(); n++) {
auto d = new sortNodeData;
try {
d->ASC = sortParams[n].second;
d->calculationNodeID = sortParams[n].first->id();
if (sortParams[n].first->getType() == EN::CALCULATION) {
auto cn = static_cast<triagens::aql::CalculationNode*>(sortParams[n].first);
auto oneSortExpression = cn->expression();
if (oneSortExpression->isAttributeAccess()) {
auto simpleExpression = oneSortExpression->getMultipleAttributes();
d->variableName = simpleExpression.first;
d->attributevec = simpleExpression.second;
}
}
_sortNodeData.push_back(d);
}
catch (...) {
delete d;
throw;
}
}
}
~SortAnalysis () {
for (auto x : _sortNodeData){
delete x;
}
}
////////////////////////////////////////////////////////////////////////////////
/// @brief checks the whether we only have simple calculation nodes
////////////////////////////////////////////////////////////////////////////////
bool isAnalyzeable () {
if (_sortNodeData.size() == 0) {
return false;
}
size_t j;
for (j = 0; j < _sortNodeData.size(); j ++) {
if (_sortNodeData[j]->variableName.length() == 0) {
return false;
}
}
/* are we all from one variable? * /
int j = 0;
for (; (j < _sortNodeData.size() &&
sortNodeData[j]->variableName.length() == 0);
j ++);
last = sortNodeData[j];
j ++;
for (j < _sortNodeData.size(); j++) {
if (sortNodeData[j]->variableName.length)
if (last->variableName != sortNodeData[j]->variableName) {
return false;
}
last = sortNodeData[j];
}
alle nodes gesetzt, ja.
*/
return true;
}
////////////////////////////////////////////////////////////////////////////////
/// @brief checks whether our calculation nodes reference variableName;
/// @returns pair used for further processing with the indices.
////////////////////////////////////////////////////////////////////////////////
Range_IndexPair getAttrsForVariableName (std::string &variableName) {
ECN::IndexMatchVec v;
IndexOrCondition rangeInfo;
for (size_t j = 0; j < _sortNodeData.size(); j ++) {
if (_sortNodeData[j]->variableName != variableName) {
return std::make_pair(v, rangeInfo); // for now, no mixed support.
}
}
// Collect the right data for the sorting:
for (size_t j = 0; j < _sortNodeData.size(); j ++) {
v.push_back(std::make_pair(_sortNodeData[j]->attributevec,
_sortNodeData[j]->ASC));
}
// We only need one or-condition (because this is mandatory) which
// refers to 0 of the attributes:
rangeInfo.push_back(std::vector<RangeInfo>());
return std::make_pair(v, rangeInfo);
}
////////////////////////////////////////////////////////////////////////////////
/// @brief removes the sortNode and its referenced Calculationnodes from
/// the plan.
////////////////////////////////////////////////////////////////////////////////
void removeSortNodeFromPlan (ExecutionPlan *newPlan) {
newPlan->unlinkNode(newPlan->getNodeById(sortNodeID));
}
};
class sortToIndexNode : public WalkerWorker<ExecutionNode> {
using ECN = triagens::aql::EnumerateCollectionNode;
Optimizer* _opt;
ExecutionPlan* _plan;
SortAnalysis* _sortNode;
Optimizer::RuleLevel _level;
public:
bool planModified;
sortToIndexNode (Optimizer* opt,
ExecutionPlan* plan,
SortAnalysis* Node,
Optimizer::RuleLevel level)
: _opt(opt),
_plan(plan),
_sortNode(Node),
_level(level) {
planModified = false;
}
////////////////////////////////////////////////////////////////////////////////
/// @brief if the sort is already done by an indexrange, remove the sort.
////////////////////////////////////////////////////////////////////////////////
bool handleIndexRangeNode (IndexRangeNode* node) {
auto variableName = node->getVariablesSetHere()[0]->name;
auto result = _sortNode->getAttrsForVariableName(variableName);
if (node->MatchesIndex(result.first)) {
_sortNode->removeSortNodeFromPlan(_plan);
planModified = true;
}
return true;
}
////////////////////////////////////////////////////////////////////////////////
/// @brief check whether we can sort via an index.
////////////////////////////////////////////////////////////////////////////////
bool handleEnumerateCollectionNode (EnumerateCollectionNode* node, Optimizer::RuleLevel level) {
auto variableName = node->getVariablesSetHere()[0]->name;
auto result = _sortNode->getAttrsForVariableName(variableName);
if (result.first.size() == 0) {
return true; // we didn't find anything replaceable by indice
}
for (auto idx: node->getIndicesOrdered(result.first)) {
// make one new plan for each index that replaces this
// EnumerateCollectionNode with an IndexRangeNode
// can only use the index if it is a skip list or (a hash and we
// are checking equality)
auto newPlan = _plan->clone();
try {
ExecutionNode* newNode = new IndexRangeNode( newPlan->nextId(),
node->vocbase(),
node->collection(),
node->outVariable(),
idx.index,/// TODO: estimate cost on match quality
result.second);
newPlan->registerNode(newNode);
newPlan->replaceNode(newPlan->getNodeById(node->id()), newNode);
if (idx.fullmatch) { // if the index superseedes the sort, remove it.
_sortNode->removeSortNodeFromPlan(newPlan);
_opt->addPlan(newPlan, Optimizer::RuleLevel::pass5, true);
}
else {
_opt->addPlan(newPlan, level, true);
}
}
catch (...) {
delete newPlan;
throw;
}
}
return true;
}
bool enterSubQuery () { return false; }
bool before (ExecutionNode* en) {
switch (en->getType()) {
case EN::ENUMERATE_LIST:
case EN::CALCULATION:
case EN::SUBQUERY: /// TODO: find out whether it may throw
case EN::FILTER:
return false; // skip. we don't care.
case EN::INTERSECTION:
case EN::SINGLETON:
case EN::AGGREGATE:
case EN::LOOKUP_JOIN:
case EN::MERGE_JOIN:
case EN::LOOKUP_INDEX_UNIQUE:
case EN::LOOKUP_INDEX_RANGE:
case EN::LOOKUP_FULL_COLLECTION:
case EN::CONCATENATION:
case EN::MERGE:
case EN::REMOTE:
case EN::INSERT:
case EN::REMOVE:
case EN::REPLACE:
case EN::UPDATE:
case EN::RETURN:
case EN::NORESULTS:
case EN::ILLEGAL:
case EN::LIMIT: // LIMIT is criterion to stop
return true; // abort.
case EN::SORT: // pulling two sorts together is done elsewhere.
return en->id() != _sortNode->sortNodeID; // ignore ourselves.
case EN::INDEX_RANGE:
return handleIndexRangeNode(static_cast<IndexRangeNode*>(en));
case EN::ENUMERATE_COLLECTION:
return handleEnumerateCollectionNode(static_cast<EnumerateCollectionNode*>(en), _level);
}
return true;
}
};
int triagens::aql::useIndexForSort (Optimizer* opt,
ExecutionPlan* plan,
Optimizer::Rule const* rule) {
bool planModified = false;
std::vector<ExecutionNode*> nodes
= plan->findNodesOfType(triagens::aql::ExecutionNode::SORT, true);
for (auto n : nodes) {
auto thisSortNode = static_cast<SortNode*>(n);
SortAnalysis node(thisSortNode);
if (node.isAnalyzeable()) {
sortToIndexNode finder(opt, plan, &node, rule->level);
thisSortNode->walk(&finder);/// todo auf der dependency anfangen
if (finder.planModified) {
planModified = true;
}
}
}
opt->addPlan(plan,
planModified ? Optimizer::RuleLevel::pass5 : rule->level,
planModified);
return TRI_ERROR_NO_ERROR;
}
////////////////////////////////////////////////////////////////////////////////
/// @brief helper to compute lots of permutation tuples
/// a permutation tuple is represented as a single vector together with
/// another vector describing the boundaries of the tuples.
/// Example:
/// data: 0,1,2, 3,4, 5,6
/// starts: 0, 3, 5, (indices of starts of sections)
/// means a tuple of 3 permutations of 3, 2 and 2 points respectively
/// This function computes the next permutation tuple among the
/// lexicographically sorted list of all such tuples. It returns true
/// if it has successfully computed this and false if the tuple is already
/// the lexicographically largest one. If false is returned, the permutation
/// tuple is back to the beginning.
////////////////////////////////////////////////////////////////////////////////
static bool nextPermutationTuple (std::vector<size_t>& data,
std::vector<size_t>& starts) {
auto begin = data.begin(); // a random access iterator
for (size_t i = starts.size(); i-- != 0; ) {
std::vector<size_t>::iterator from = begin + starts[i];
std::vector<size_t>::iterator to;
if (i == starts.size()-1) {
to = data.end();
}
else {
to = begin + starts[i+1];
}
if (std::next_permutation(from, to)) {
return true;
}
}
return false;
}
////////////////////////////////////////////////////////////////////////////////
/// @brief interchange adjacent EnumerateCollectionNodes in all possible ways
////////////////////////////////////////////////////////////////////////////////
int triagens::aql::interchangeAdjacentEnumerations (Optimizer* opt,
ExecutionPlan* plan,
Optimizer::Rule const* rule) {
std::vector<ExecutionNode*> nodes
= plan->findNodesOfType(triagens::aql::ExecutionNode::ENUMERATE_COLLECTION,
true);
std::unordered_set<ExecutionNode*> nodesSet;
for (auto n : nodes) {
TRI_ASSERT(nodesSet.find(n) == nodesSet.end());
nodesSet.insert(n);
}
std::vector<ExecutionNode*> nodesToPermute;
std::vector<size_t> permTuple;
std::vector<size_t> starts;
// We use that the order of the nodes is such that a node B that is among the
// recursive dependencies of a node A is later in the vector.
for (auto n : nodes) {
if (nodesSet.find(n) != nodesSet.end()) {
std::vector<ExecutionNode*> nn;
nn.push_back(n);
nodesSet.erase(n);
// Now follow the dependencies as long as we see further such nodes:
auto nwalker = n;
while (true) {
auto deps = nwalker->getDependencies();
if (deps.size() == 0) {
break;
}
if (deps[0]->getType() !=
triagens::aql::ExecutionNode::ENUMERATE_COLLECTION) {
break;
}
nwalker = deps[0];
nn.push_back(nwalker);
nodesSet.erase(nwalker);
}
if (nn.size() > 1) {
// Move it into the permutation tuple:
starts.push_back(permTuple.size());
for (auto nnn : nn) {
nodesToPermute.push_back(nnn);
permTuple.push_back(permTuple.size());
}
}
}
}
// Now we have collected all the runs of EnumerateCollectionNodes in the
// plan, we need to compute all possible permutations of all of them,
// independently. This is why we need to compute all permutation tuples.
opt->addPlan(plan, rule->level, false);
if (! starts.empty()) {
nextPermutationTuple(permTuple, starts); // will never return false
do {
// Clone the plan:
auto newPlan = plan->clone();
try { // get rid of plan if any of this fails
// Find the nodes in the new plan corresponding to the ones in the
// old plan that we want to permute:
std::vector<ExecutionNode*> newNodes;
for (size_t j = 0; j < nodesToPermute.size(); j++) {
newNodes.push_back(newPlan->getNodeById(nodesToPermute[j]->id()));
}
// Now get going with the permutations:
for (size_t i = 0; i < starts.size(); i++) {
size_t lowBound = starts[i];
size_t highBound = (i < starts.size()-1)
? starts[i+1]
: permTuple.size();
// We need to remove the nodes
// newNodes[lowBound..highBound-1] in newPlan and replace
// them by the same ones in a different order, given by
// permTuple[lowBound..highBound-1].
auto parents = newNodes[lowBound]->getParents();
TRI_ASSERT(parents.size() == 1);
auto parent = parents[0]; // needed for insertion later
// Unlink all those nodes:
for (size_t j = lowBound; j < highBound; j++) {
newPlan->unlinkNode(newNodes[j]);
}
// And insert them in the new order:
for (size_t j = highBound; j-- != lowBound; ) {
newPlan->insertDependency(parent, newNodes[permTuple[j]]);
}
}
// OK, the new plan is ready, let's report it:
if (! opt->addPlan(newPlan, rule->level, true)) {
break;
}
}
catch (...) {
delete newPlan;
throw;
}
}
while (nextPermutationTuple(permTuple, starts));
}
return TRI_ERROR_NO_ERROR;
}
// Local Variables:
// mode: outline-minor
// outline-regexp: "^\\(/// @brief\\|/// {@inheritDoc}\\|/// @addtogroup\\|// --SECTION--\\|/// @\\}\\)"
// End:
Reference in New Issue View Git Blame Copy Permalink