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/**
* Copyright (C) 2013 10gen Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License, version 3,
* as published by the Free Software Foundation.
*
* 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
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
* 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 GNU Affero General 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 "mongo/db/query/canonical_query.h"
#include "mongo/db/query/query_planner_params.h"
#include "mongo/db/query/query_solution.h"
namespace mongo {
class CachedSolution;
class Collection;
/**
* QueryPlanner's job is to provide an entry point to the query planning and optimization
* process.
*/
class QueryPlanner {
public:
// Identifies the version of the query planner module. Reported in explain.
static const int kPlannerVersion;
/**
* Outputs a series of possible solutions for the provided 'query' into 'out'. Uses the
* indices and other data in 'params' to plan with.
*
* Caller owns pointers in *out.
*/
static Status plan(const CanonicalQuery& query,
const QueryPlannerParams& params,
std::vector<QuerySolution*>* out);
/**
* Attempt to generate a query solution, given data retrieved
* from the plan cache.
*
* @param query -- query for which we are generating a plan
* @param params -- planning parameters
* @param cachedSoln -- the CachedSolution retrieved from the plan cache.
* @param out -- an out-parameter which will be filled in with the solution
* generated from the cache data
*
* On success, the caller is responsible for deleting *out.
*/
static Status planFromCache(const CanonicalQuery& query,
const QueryPlannerParams& params,
const CachedSolution& cachedSoln,
QuerySolution** out);
/**
* Used to generated the index tag tree that will be inserted
* into the plan cache. This data gets stashed inside a QuerySolution
* until it can be inserted into the cache proper.
*
* @param taggedTree -- a MatchExpression with index tags that has been
* produced by the enumerator.
* @param relevantIndices -- a list of the index entries used to tag
* the tree (i.e. index numbers in the tags refer to entries in this vector)
*
* On success, a new tagged tree is returned through the out-parameter 'out'.
* The caller has ownership of both taggedTree and *out.
*
* On failure, 'out' is set to NULL.
*/
static Status cacheDataFromTaggedTree(const MatchExpression* const taggedTree,
const std::vector<IndexEntry>& relevantIndices,
PlanCacheIndexTree** out);
/**
* @param filter -- an untagged MatchExpression
* @param indexTree -- a tree structure retrieved from the
* cache with index tags that indicates how 'filter' should
* be tagged.
* @param indexMap -- needed in order to put the proper index
* numbers inside the index tags
*
* On success, 'filter' is mutated so that it has all the
* index tags needed in order for the access planner to recreate
* the cached plan.
*
* On failure, the tag state attached to the nodes of 'filter'
* is invalid. Planning from the cache should be aborted.
*
* Does not take ownership of either filter or indexTree.
*/
static Status tagAccordingToCache(MatchExpression* filter,
const PlanCacheIndexTree* const indexTree,
const std::map<BSONObj, size_t>& indexMap);
};
} // namespace mongo
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