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+/**
+ *    Copyright (C) 2014 MongoDB 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
+
+namespace mongo {
+
+    //
+    // multi-plan ranking
+    //
+
+    // Max number of times we call work() on plans before comparing them,
+    // for small collections.
+    extern int internalQueryPlanEvaluationWorks;
+
+    // For large collections, the number times we work() candidate plans is
+    // taken as this fraction of the collection size.
+    extern double internalQueryPlanEvaluationCollFraction;
+
+    // Stop working plans once a plan returns this many results.
+    extern int internalQueryPlanEvaluationMaxResults;
+
+    // Do we give a big ranking bonus to intersection plans?
+    extern bool internalQueryForceIntersectionPlans;
+
+    // Do we have ixisect on at all?
+    extern bool internalQueryPlannerEnableIndexIntersection;
+
+    // Do we use hash-based intersection for rooted $and queries?
+    extern bool internalQueryPlannerEnableHashIntersection;
+
+    //
+    // plan cache
+    //
+
+    // How many entries in the cache?
+    extern int internalQueryCacheSize;
+
+    // How many feedback entries do we collect before possibly evicting from the cache based on bad
+    // performance?
+    extern int internalQueryCacheFeedbacksStored;
+
+    // How many stddevs must a feedback be from the 'reference' performance for us to evict the
+    // entry from the cache?
+    extern double internalQueryCacheStdDeviations;
+
+    // How many write ops should we allow in a collection before tossing all cache entries?
+    extern int internalQueryCacheWriteOpsBetweenFlush;
+
+    //
+    // Planning and enumeration.
+    //
+
+    // How many indexed solutions will QueryPlanner::plan output?
+    extern int internalQueryPlannerMaxIndexedSolutions;
+
+    // How many solutions will the enumerator consider at each OR?
+    extern int internalQueryEnumerationMaxOrSolutions;
+
+    // How many intersections will the enumerator consider at each AND?
+    extern int internalQueryEnumerationMaxIntersectPerAnd;
+
+    // Do we want to plan each child of the OR independently?
+    extern bool internalQueryPlanOrChildrenIndependently;
+
+    // How many index scans are we willing to produce in order to obtain a sort order
+    // during explodeForSort?
+    extern int internalQueryMaxScansToExplode;
+
+}  // namespace mongo