/**
 *    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.
 */

/**
 * This file tests db/exec/and_*.cpp and DiskLoc invalidation.  DiskLoc invalidation forces a fetch
 * so we cannot test it outside of a dbtest.
 */

#include <boost/shared_ptr.hpp>

#include "mongo/client/dbclientcursor.h"
#include "mongo/db/catalog/database.h"
#include "mongo/db/exec/and_hash.h"
#include "mongo/db/exec/and_sorted.h"
#include "mongo/db/exec/fetch.h"
#include "mongo/db/exec/index_scan.h"
#include "mongo/db/exec/plan_stage.h"
#include "mongo/db/instance.h"
#include "mongo/db/json.h"
#include "mongo/db/matcher/expression_parser.h"
#include "mongo/db/pdfile.h"
#include "mongo/db/catalog/collection.h"
#include "mongo/db/structure/collection_iterator.h"
#include "mongo/dbtests/dbtests.h"
#include "mongo/util/mongoutils/str.h"

namespace QueryStageAnd {

    class QueryStageAndBase {
    public:
        QueryStageAndBase() { }

        virtual ~QueryStageAndBase() {
            _client.dropCollection(ns());
        }

        void addIndex(const BSONObj& obj) {
            _client.ensureIndex(ns(), obj);
        }

        IndexDescriptor* getIndex(const BSONObj& obj, Collection* coll) {
            IndexDescriptor* descriptor = coll->getIndexCatalog()->findIndexByKeyPattern( obj );
            if (NULL == descriptor) {
                FAIL(mongoutils::str::stream() << "Unable to find index with key pattern " << obj);
            }
            return descriptor;
        }

        void getLocs(set<DiskLoc>* out, Collection* coll) {
            CollectionIterator* it = coll->getIterator(DiskLoc(), false,
                                                       CollectionScanParams::FORWARD);
            while (!it->isEOF()) {
                DiskLoc nextLoc = it->getNext();
                out->insert(nextLoc);
            }
            delete it;
        }

        void insert(const BSONObj& obj) {
            _client.insert(ns(), obj);
        }

        void remove(const BSONObj& obj) {
            _client.remove(ns(), obj);
        }

        /**
         * Executes plan stage until EOF.
         * Returns number of results seen if execution reaches EOF successfully.
         * Otherwise, returns -1 on stage failure.
         */
        int countResults(PlanStage* stage) {
            int count = 0;
            while (!stage->isEOF()) {
                WorkingSetID id = WorkingSet::INVALID_ID;
                PlanStage::StageState status = stage->work(&id);
                if (PlanStage::FAILURE == status) {
                    return -1;
                }
                if (PlanStage::ADVANCED != status) { continue; }
                ++count;
            }
            return count;
        }

        /**
         * Gets the next result from 'stage'.
         *
         * Fails if the stage fails or returns DEAD, if the returned working
         * set member is not fetched, or if there are no more results.
         */
        BSONObj getNext(PlanStage* stage, WorkingSet* ws) {
            while (!stage->isEOF()) {
                WorkingSetID id = WorkingSet::INVALID_ID;
                PlanStage::StageState status = stage->work(&id);

                // We shouldn't fail or be dead.
                ASSERT(PlanStage::FAILURE != status);
                ASSERT(PlanStage::DEAD != status);

                if (PlanStage::ADVANCED != status) { continue; }

                WorkingSetMember* member = ws->get(id);
                ASSERT(member->hasObj());
                return member->obj;
            }

            // We failed to produce a result.
            ASSERT(false);
            return BSONObj();
        }

        static const char* ns() { return "unittests.QueryStageAnd"; }

    private:
        static DBDirectClient _client;
    };

    DBDirectClient QueryStageAndBase::_client;

    //
    // Hash AND tests
    //

    /**
     * Invalidate a DiskLoc held by a hashed AND before the AND finishes evaluating.  The AND should
     * process all other data just fine and flag the invalidated DiskLoc in the WorkingSet.
     */
    class QueryStageAndHashInvalidation : public QueryStageAndBase {
    public:
        void run() {
            Client::WriteContext ctx(ns());
            Database* db = ctx.ctx().db();
            Collection* coll = db->getCollection(ns());
            if (!coll) {
                coll = db->createCollection(ns());
            }

            for (int i = 0; i < 50; ++i) {
                insert(BSON("foo" << i << "bar" << i));
            }

            addIndex(BSON("foo" << 1));
            addIndex(BSON("bar" << 1));

            WorkingSet ws;
            scoped_ptr<AndHashStage> ah(new AndHashStage(&ws, NULL));

            // Foo <= 20
            IndexScanParams params;
            params.descriptor = getIndex(BSON("foo" << 1), coll);
            params.bounds.isSimpleRange = true;
            params.bounds.startKey = BSON("" << 20);
            params.bounds.endKey = BSONObj();
            params.bounds.endKeyInclusive = true;
            params.direction = -1;
            ah->addChild(new IndexScan(params, &ws, NULL));

            // Bar >= 10
            params.descriptor = getIndex(BSON("bar" << 1), coll);
            params.bounds.startKey = BSON("" << 10);
            params.bounds.endKey = BSONObj();
            params.bounds.endKeyInclusive = true;
            params.direction = 1;
            ah->addChild(new IndexScan(params, &ws, NULL));

            // ah reads the first child into its hash table.
            // ah should read foo=20, foo=19, ..., foo=0 in that order.
            // Read half of them...
            for (int i = 0; i < 10; ++i) {
                WorkingSetID out;
                PlanStage::StageState status = ah->work(&out);
                ASSERT_EQUALS(PlanStage::NEED_TIME, status);
            }

            // ...yield
            ah->prepareToYield();
            // ...invalidate one of the read objects
            set<DiskLoc> data;
            getLocs(&data, coll);
            size_t memUsageBefore = ah->getMemUsage();
            for (set<DiskLoc>::const_iterator it = data.begin(); it != data.end(); ++it) {
                if (it->obj()["foo"].numberInt() == 15) {
                    ah->invalidate(*it, INVALIDATION_DELETION);
                    remove(it->obj());
                    break;
                }
            }
            size_t memUsageAfter = ah->getMemUsage();
            ah->recoverFromYield();

            // Invalidating a read object should decrease memory usage.
            ASSERT_LESS_THAN(memUsageAfter, memUsageBefore);

            // And expect to find foo==15 it flagged for review.
            const unordered_set<WorkingSetID>& flagged = ws.getFlagged();
            ASSERT_EQUALS(size_t(1), flagged.size());

            // Expect to find the right value of foo in the flagged item.
            WorkingSetMember* member = ws.get(*flagged.begin());
            ASSERT_TRUE(NULL != member);
            ASSERT_EQUALS(WorkingSetMember::OWNED_OBJ, member->state);
            BSONElement elt;
            ASSERT_TRUE(member->getFieldDotted("foo", &elt));
            ASSERT_EQUALS(15, elt.numberInt());

            // Now, finish up the AND.  Since foo == bar, we would have 11 results, but we subtract
            // one because of a mid-plan invalidation, so 10.
            int count = 0;
            while (!ah->isEOF()) {
                WorkingSetID id = WorkingSet::INVALID_ID;
                PlanStage::StageState status = ah->work(&id);
                if (PlanStage::ADVANCED != status) { continue; }

                ++count;
                member = ws.get(id);

                ASSERT_TRUE(member->getFieldDotted("foo", &elt));
                ASSERT_LESS_THAN_OR_EQUALS(elt.numberInt(), 20);
                ASSERT_NOT_EQUALS(15, elt.numberInt());
                ASSERT_TRUE(member->getFieldDotted("bar", &elt));
                ASSERT_GREATER_THAN_OR_EQUALS(elt.numberInt(), 10);
            }

            ASSERT_EQUALS(10, count);
        }
    };

    // Invalidate one of the "are we EOF?" lookahead results.
    class QueryStageAndHashInvalidateLookahead : public QueryStageAndBase {
    public:
        void run() {
            Client::WriteContext ctx(ns());
            Database* db = ctx.ctx().db();
            Collection* coll = db->getCollection(ns());
            if (!coll) {
                coll = db->createCollection(ns());
            }

            for (int i = 0; i < 50; ++i) {
                insert(BSON("_id" << i << "foo" << i << "bar" << i << "baz" << i));
            }

            addIndex(BSON("foo" << 1));
            addIndex(BSON("bar" << 1));
            addIndex(BSON("baz" << 1));

            WorkingSet ws;
            scoped_ptr<AndHashStage> ah(new AndHashStage(&ws, NULL));

            // Foo <= 20 (descending)
            IndexScanParams params;
            params.descriptor = getIndex(BSON("foo" << 1), coll);
            params.bounds.isSimpleRange = true;
            params.bounds.startKey = BSON("" << 20);
            params.bounds.endKey = BSONObj();
            params.bounds.endKeyInclusive = true;
            params.direction = -1;
            ah->addChild(new IndexScan(params, &ws, NULL));

            // Bar <= 19 (descending)
            params.descriptor = getIndex(BSON("bar" << 1), coll);
            params.bounds.startKey = BSON("" << 19);
            ah->addChild(new IndexScan(params, &ws, NULL));

            // First call to work reads the first result from the children.
            // The first result is for the first scan over foo is {foo: 20, bar: 20, baz: 20}.
            // The first result is for the second scan over bar is {foo: 19, bar: 19, baz: 19}.
            WorkingSetID id = WorkingSet::INVALID_ID;
            PlanStage::StageState status = ah->work(&id);
            ASSERT_EQUALS(PlanStage::NEED_TIME, status);

            const unordered_set<WorkingSetID>& flagged = ws.getFlagged();
            ASSERT_EQUALS(size_t(0), flagged.size());

            // "delete" deletedObj (by invalidating the DiskLoc of the obj that matches it).
            BSONObj deletedObj = BSON("_id" << 20 << "foo" << 20 << "bar" << 20 << "baz" << 20);
            ah->prepareToYield();
            set<DiskLoc> data;
            getLocs(&data, coll);

            size_t memUsageBefore = ah->getMemUsage();
            for (set<DiskLoc>::const_iterator it = data.begin(); it != data.end(); ++it) {
                if (0 == deletedObj.woCompare(it->obj())) {
                    ah->invalidate(*it, INVALIDATION_DELETION);
                    break;
                }
            }

            size_t memUsageAfter = ah->getMemUsage();
            // Look ahead results do not count towards memory usage.
            ASSERT_EQUALS(memUsageBefore, memUsageAfter);

            ah->recoverFromYield();

            // The deleted obj should show up in flagged.
            ASSERT_EQUALS(size_t(1), flagged.size());

            // And not in our results.
            int count = 0;
            while (!ah->isEOF()) {
                WorkingSetID id = WorkingSet::INVALID_ID;
                PlanStage::StageState status = ah->work(&id);
                if (PlanStage::ADVANCED != status) { continue; }
                WorkingSetMember* wsm = ws.get(id);
                ASSERT_NOT_EQUALS(0, deletedObj.woCompare(wsm->loc.obj()));
                ++count;
            }

            ASSERT_EQUALS(count, 20);
        }
    };

    // An AND with two children.
    class QueryStageAndHashTwoLeaf : public QueryStageAndBase {
    public:
        void run() {
            Client::WriteContext ctx(ns());
            Database* db = ctx.ctx().db();
            Collection* coll = db->getCollection(ns());
            if (!coll) {
                coll = db->createCollection(ns());
            }

            for (int i = 0; i < 50; ++i) {
                insert(BSON("foo" << i << "bar" << i));
            }

            addIndex(BSON("foo" << 1));
            addIndex(BSON("bar" << 1));

            WorkingSet ws;
            scoped_ptr<AndHashStage> ah(new AndHashStage(&ws, NULL));

            // Foo <= 20
            IndexScanParams params;
            params.descriptor = getIndex(BSON("foo" << 1), coll);
            params.bounds.isSimpleRange = true;
            params.bounds.startKey = BSON("" << 20);
            params.bounds.endKey = BSONObj();
            params.bounds.endKeyInclusive = true;
            params.direction = -1;
            ah->addChild(new IndexScan(params, &ws, NULL));

            // Bar >= 10
            params.descriptor = getIndex(BSON("bar" << 1), coll);
            params.bounds.startKey = BSON("" << 10);
            params.bounds.endKey = BSONObj();
            params.bounds.endKeyInclusive = true;
            params.direction = 1;
            ah->addChild(new IndexScan(params, &ws, NULL));

            // foo == bar == baz, and foo<=20, bar>=10, so our values are:
            // foo == 10, 11, 12, 13, 14, 15. 16, 17, 18, 19, 20
            ASSERT_EQUALS(11, countResults(ah.get()));
        }
    };

    // An AND with two children.
    // Add large keys (512 bytes) to index of first child to cause
    // internal buffer within hashed AND to exceed threshold (32MB)
    // before gathering all requested results.
    class QueryStageAndHashTwoLeafFirstChildLargeKeys : public QueryStageAndBase {
    public:
        void run() {
            Client::WriteContext ctx(ns());
            Database* db = ctx.ctx().db();
            Collection* coll = db->getCollection(ns());
            if (!coll) {
                coll = db->createCollection(ns());
            }

            // Generate large keys for {foo: 1, big: 1} index.
            std::string big(512, 'a');
            for (int i = 0; i < 50; ++i) {
                insert(BSON("foo" << i << "bar" << i << "big" << big));
            }

            addIndex(BSON("foo" << 1 << "big" << 1));
            addIndex(BSON("bar" << 1));

            // Lower buffer limit to 20 * sizeof(big) to force memory error
            // before hashed AND is done reading the first child (stage has to
            // hold 21 keys in buffer for Foo <= 20).
            WorkingSet ws;
            scoped_ptr<AndHashStage> ah(new AndHashStage(&ws, NULL, 20 * big.size()));

            // Foo <= 20
            IndexScanParams params;
            params.descriptor = getIndex(BSON("foo" << 1 << "big" << 1), coll);
            params.bounds.isSimpleRange = true;
            params.bounds.startKey = BSON("" << 20 << "" << big);
            params.bounds.endKey = BSONObj();
            params.bounds.endKeyInclusive = true;
            params.direction = -1;
            ah->addChild(new IndexScan(params, &ws, NULL));

            // Bar >= 10
            params.descriptor = getIndex(BSON("bar" << 1), coll);
            params.bounds.startKey = BSON("" << 10);
            params.bounds.endKey = BSONObj();
            params.bounds.endKeyInclusive = true;
            params.direction = 1;
            ah->addChild(new IndexScan(params, &ws, NULL));

            // Stage execution should fail.
            ASSERT_EQUALS(-1, countResults(ah.get()));
        }
    };

    // An AND with three children.
    // Add large keys (512 bytes) to index of last child to verify that
    // keys in last child are not buffered
    class QueryStageAndHashTwoLeafLastChildLargeKeys : public QueryStageAndBase {
    public:
        void run() {
            Client::WriteContext ctx(ns());
            Database* db = ctx.ctx().db();
            Collection* coll = db->getCollection(ns());
            if (!coll) {
                coll = db->createCollection(ns());
            }

            // Generate large keys for {baz: 1, big: 1} index.
            std::string big(512, 'a');
            for (int i = 0; i < 50; ++i) {
                insert(BSON("foo" << i << "bar" << i << "big" << big));
            }

            addIndex(BSON("foo" << 1));
            addIndex(BSON("bar" << 1 << "big" << 1));

            // Lower buffer limit to 5 * sizeof(big) to ensure that
            // keys in last child's index are not buffered. There are 6 keys
            // that satisfy the criteria Foo <= 20 and Bar >= 10 and 5 <= baz <= 15.
            WorkingSet ws;
            scoped_ptr<AndHashStage> ah(new AndHashStage(&ws, NULL, 5 * big.size()));

            // Foo <= 20
            IndexScanParams params;
            params.descriptor = getIndex(BSON("foo" << 1), coll);
            params.bounds.isSimpleRange = true;
            params.bounds.startKey = BSON("" << 20);
            params.bounds.endKey = BSONObj();
            params.bounds.endKeyInclusive = true;
            params.direction = -1;
            ah->addChild(new IndexScan(params, &ws, NULL));

            // Bar >= 10
            params.descriptor = getIndex(BSON("bar" << 1 << "big" << 1), coll);
            params.bounds.startKey = BSON("" << 10 << "" << big);
            params.bounds.endKey = BSONObj();
            params.bounds.endKeyInclusive = true;
            params.direction = 1;
            ah->addChild(new IndexScan(params, &ws, NULL));

            // foo == bar == baz, and foo<=20, bar>=10, so our values are:
            // foo == 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20.
            ASSERT_EQUALS(11, countResults(ah.get()));
        }
    };

    // An AND with three children.
    class QueryStageAndHashThreeLeaf : public QueryStageAndBase {
    public:
        void run() {
            Client::WriteContext ctx(ns());
            Database* db = ctx.ctx().db();
            Collection* coll = db->getCollection(ns());
            if (!coll) {
                coll = db->createCollection(ns());
            }

            for (int i = 0; i < 50; ++i) {
                insert(BSON("foo" << i << "bar" << i << "baz" << i));
            }

            addIndex(BSON("foo" << 1));
            addIndex(BSON("bar" << 1));
            addIndex(BSON("baz" << 1));

            WorkingSet ws;
            scoped_ptr<AndHashStage> ah(new AndHashStage(&ws, NULL));

            // Foo <= 20
            IndexScanParams params;
            params.descriptor = getIndex(BSON("foo" << 1), coll);
            params.bounds.isSimpleRange = true;
            params.bounds.startKey = BSON("" << 20);
            params.bounds.endKey = BSONObj();
            params.bounds.endKeyInclusive = true;
            params.direction = -1;
            ah->addChild(new IndexScan(params, &ws, NULL));

            // Bar >= 10
            params.descriptor = getIndex(BSON("bar" << 1), coll);
            params.bounds.startKey = BSON("" << 10);
            params.bounds.endKey = BSONObj();
            params.bounds.endKeyInclusive = true;
            params.direction = 1;
            ah->addChild(new IndexScan(params, &ws, NULL));

            // 5 <= baz <= 15
            params.descriptor = getIndex(BSON("baz" << 1), coll);
            params.bounds.startKey = BSON("" << 5);
            params.bounds.endKey = BSON("" << 15);
            params.bounds.endKeyInclusive = true;
            params.direction = 1;
            ah->addChild(new IndexScan(params, &ws, NULL));

            // foo == bar == baz, and foo<=20, bar>=10, 5<=baz<=15, so our values are:
            // foo == 10, 11, 12, 13, 14, 15.
            ASSERT_EQUALS(6, countResults(ah.get()));
        }
    };

    // An AND with three children.
    // Add large keys (512 bytes) to index of second child to cause
    // internal buffer within hashed AND to exceed threshold (32MB)
    // before gathering all requested results.
    // We need 3 children because the hashed AND stage buffered data for
    // N-1 of its children. If the second child is the last child, it will not
    // be buffered.
    class QueryStageAndHashThreeLeafMiddleChildLargeKeys : public QueryStageAndBase {
    public:
        void run() {
            Client::WriteContext ctx(ns());
            Database* db = ctx.ctx().db();
            Collection* coll = db->getCollection(ns());
            if (!coll) {
                coll = db->createCollection(ns());
            }

            // Generate large keys for {bar: 1, big: 1} index.
            std::string big(512, 'a');
            for (int i = 0; i < 50; ++i) {
                insert(BSON("foo" << i << "bar" << i << "baz" << i << "big" << big));
            }

            addIndex(BSON("foo" << 1));
            addIndex(BSON("bar" << 1 << "big" << 1));
            addIndex(BSON("baz" << 1));

            // Lower buffer limit to 10 * sizeof(big) to force memory error
            // before hashed AND is done reading the second child (stage has to
            // hold 11 keys in buffer for Foo <= 20 and Bar >= 10).
            WorkingSet ws;
            scoped_ptr<AndHashStage> ah(new AndHashStage(&ws, NULL, 10 * big.size()));

            // Foo <= 20
            IndexScanParams params;
            params.descriptor = getIndex(BSON("foo" << 1), coll);
            params.bounds.isSimpleRange = true;
            params.bounds.startKey = BSON("" << 20);
            params.bounds.endKey = BSONObj();
            params.bounds.endKeyInclusive = true;
            params.direction = -1;
            ah->addChild(new IndexScan(params, &ws, NULL));

            // Bar >= 10
            params.descriptor = getIndex(BSON("bar" << 1 << "big" << 1), coll);
            params.bounds.startKey = BSON("" << 10 << "" << big);
            params.bounds.endKey = BSONObj();
            params.bounds.endKeyInclusive = true;
            params.direction = 1;
            ah->addChild(new IndexScan(params, &ws, NULL));

            // 5 <= baz <= 15
            params.descriptor = getIndex(BSON("baz" << 1), coll);
            params.bounds.startKey = BSON("" << 5);
            params.bounds.endKey = BSON("" << 15);
            params.bounds.endKeyInclusive = true;
            params.direction = 1;
            ah->addChild(new IndexScan(params, &ws, NULL));

            // Stage execution should fail.
            ASSERT_EQUALS(-1, countResults(ah.get()));
        }
    };

    // An AND with an index scan that returns nothing.
    class QueryStageAndHashWithNothing : public QueryStageAndBase {
    public:
        void run() {
            Client::WriteContext ctx(ns());
            Database* db = ctx.ctx().db();
            Collection* coll = db->getCollection(ns());
            if (!coll) {
                coll = db->createCollection(ns());
            }

            for (int i = 0; i < 50; ++i) {
                insert(BSON("foo" << i << "bar" << 20));
            }

            addIndex(BSON("foo" << 1));
            addIndex(BSON("bar" << 1));

            WorkingSet ws;
            scoped_ptr<AndHashStage> ah(new AndHashStage(&ws, NULL));

            // Foo <= 20
            IndexScanParams params;
            params.descriptor = getIndex(BSON("foo" << 1), coll);
            params.bounds.isSimpleRange = true;
            params.bounds.startKey = BSON("" << 20);
            params.bounds.endKey = BSONObj();
            params.bounds.endKeyInclusive = true;
            params.direction = -1;
            ah->addChild(new IndexScan(params, &ws, NULL));

            // Bar == 5.  Index scan should be eof.
            params.descriptor = getIndex(BSON("bar" << 1), coll);
            params.bounds.startKey = BSON("" << 5);
            params.bounds.endKey = BSON("" << 5);
            params.bounds.endKeyInclusive = true;
            params.direction = 1;
            ah->addChild(new IndexScan(params, &ws, NULL));

            int count = 0;
            int works = 0;
            while (!ah->isEOF()) {
                WorkingSetID id = WorkingSet::INVALID_ID;
                ++works;
                PlanStage::StageState status = ah->work(&id);
                if (PlanStage::ADVANCED != status) { continue; }
                ++count;
            }

            ASSERT_EQUALS(0, count);

            // We check the "look ahead for EOF" here by examining the number of works required to
            // hit EOF.  Our first call to work will pick up that bar==5 is EOF and the AND will EOF
            // immediately.
            ASSERT_EQUALS(works, 1);
        }
    };

    // An AND that scans data but returns nothing.
    class QueryStageAndHashProducesNothing : public QueryStageAndBase {
    public:
        void run() {
            Client::WriteContext ctx(ns());
            Database* db = ctx.ctx().db();
            Collection* coll = db->getCollection(ns());
            if (!coll) {
                coll = db->createCollection(ns());
            }

            for (int i = 0; i < 10; ++i) {
                insert(BSON("foo" << (100 + i)));
                insert(BSON("bar" << i));
            }

            addIndex(BSON("foo" << 1));
            addIndex(BSON("bar" << 1));

            WorkingSet ws;
            scoped_ptr<AndHashStage> ah(new AndHashStage(&ws, NULL));

            // Foo >= 100
            IndexScanParams params;
            params.descriptor = getIndex(BSON("foo" << 1), coll);
            params.bounds.isSimpleRange = true;
            params.bounds.startKey = BSON("" << 100);
            params.bounds.endKey = BSONObj();
            params.bounds.endKeyInclusive = true;
            params.direction = 1;
            ah->addChild(new IndexScan(params, &ws, NULL));

            // Bar <= 100
            params.descriptor = getIndex(BSON("bar" << 1), coll);
            params.bounds.startKey = BSON("" << 100);
            // This is subtle and confusing.  We couldn't extract any keys from the elements with
            // 'foo' in them so we would normally index them with the "nothing found" key.  We don't
            // want to include that in our scan.
            params.bounds.endKey = BSON("" << "");
            params.bounds.endKeyInclusive = false;
            params.direction = -1;
            ah->addChild(new IndexScan(params, &ws, NULL));

            ASSERT_EQUALS(0, countResults(ah.get()));
        }
    };

    // An AND that would return more data but the matcher filters it.
    class QueryStageAndHashWithMatcher : public QueryStageAndBase {
    public:
        void run() {
            Client::WriteContext ctx(ns());
            Database* db = ctx.ctx().db();
            Collection* coll = db->getCollection(ns());
            if (!coll) {
                coll = db->createCollection(ns());
            }

            for (int i = 0; i < 50; ++i) {
                insert(BSON("foo" << i << "bar" << (100 - i)));
            }

            addIndex(BSON("foo" << 1));
            addIndex(BSON("bar" << 1));

            WorkingSet ws;
            BSONObj filter = BSON("bar" << 97);
            StatusWithMatchExpression swme = MatchExpressionParser::parse(filter);
            verify(swme.isOK());
            auto_ptr<MatchExpression> filterExpr(swme.getValue());
            scoped_ptr<AndHashStage> ah(new AndHashStage(&ws, filterExpr.get()));

            // Foo <= 20
            IndexScanParams params;
            params.descriptor = getIndex(BSON("foo" << 1), coll);
            params.bounds.isSimpleRange = true;
            params.bounds.startKey = BSON("" << 20);
            params.bounds.endKey = BSONObj();
            params.bounds.endKeyInclusive = true;
            params.direction = -1;
            ah->addChild(new IndexScan(params, &ws, NULL));

            // Bar >= 95
            params.descriptor = getIndex(BSON("bar" << 1), coll);
            params.bounds.startKey = BSON("" << 10);
            params.bounds.endKey = BSONObj();
            params.bounds.endKeyInclusive = true;
            params.direction = 1;
            ah->addChild(new IndexScan(params, &ws, NULL));

            // Bar == 97
            ASSERT_EQUALS(1, countResults(ah.get()));
        }
    };

    /**
     * SERVER-14607: Check that hash-based intersection works when the first
     * child returns fetched docs but the second child returns index keys.
     */
    class QueryStageAndHashFirstChildFetched : public QueryStageAndBase {
    public:
        void run() {
            Client::WriteContext ctx(ns());
            Database* db = ctx.ctx().db();
            Collection* coll = db->getCollection(ns());
            if (!coll) {
                coll = db->createCollection(ns());
            }

            for (int i = 0; i < 50; ++i) {
                insert(BSON("foo" << i << "bar" << i));
            }

            addIndex(BSON("foo" << 1));
            addIndex(BSON("bar" << 1));

            WorkingSet ws;
            scoped_ptr<AndHashStage> ah(new AndHashStage(&ws, NULL));

            // Foo <= 20
            IndexScanParams params;
            params.descriptor = getIndex(BSON("foo" << 1), coll);
            params.bounds.isSimpleRange = true;
            params.bounds.startKey = BSON("" << 20);
            params.bounds.endKey = BSONObj();
            params.bounds.endKeyInclusive = true;
            params.direction = -1;
            IndexScan* firstScan = new IndexScan(params, &ws, NULL);

            // First child of the AND_HASH stage is a Fetch. The NULL in the
            // constructor means there is no filter.
            FetchStage* fetch = new FetchStage(&ws, firstScan, NULL);
            ah->addChild(fetch);

            // Bar >= 10
            params.descriptor = getIndex(BSON("bar" << 1), coll);
            params.bounds.startKey = BSON("" << 10);
            params.bounds.endKey = BSONObj();
            params.bounds.endKeyInclusive = true;
            params.direction = 1;
            ah->addChild(new IndexScan(params, &ws, NULL));

            // Check that the AndHash stage returns docs {foo: 10, bar: 10}
            // through {foo: 20, bar: 20}.
            for (int i = 10; i <= 20; i++) {
                BSONObj obj = getNext(ah.get(), &ws);
                ASSERT_EQUALS(i, obj["foo"].numberInt());
                ASSERT_EQUALS(i, obj["bar"].numberInt());
            }
        }
    };

    /**
     * SERVER-14607: Check that hash-based intersection works when the first
     * child returns index keys but the second returns fetched docs.
     */
    class QueryStageAndHashSecondChildFetched : public QueryStageAndBase {
    public:
        void run() {
            Client::WriteContext ctx(ns());
            Database* db = ctx.ctx().db();
            Collection* coll = db->getCollection(ns());
            if (!coll) {
                coll = db->createCollection(ns());
            }

            for (int i = 0; i < 50; ++i) {
                insert(BSON("foo" << i << "bar" << i));
            }

            addIndex(BSON("foo" << 1));
            addIndex(BSON("bar" << 1));

            WorkingSet ws;
            scoped_ptr<AndHashStage> ah(new AndHashStage(&ws, NULL));

            // Foo <= 20
            IndexScanParams params;
            params.descriptor = getIndex(BSON("foo" << 1), coll);
            params.bounds.isSimpleRange = true;
            params.bounds.startKey = BSON("" << 20);
            params.bounds.endKey = BSONObj();
            params.bounds.endKeyInclusive = true;
            params.direction = -1;
            ah->addChild(new IndexScan(params, &ws, NULL));

            // Bar >= 10
            params.descriptor = getIndex(BSON("bar" << 1), coll);
            params.bounds.startKey = BSON("" << 10);
            params.bounds.endKey = BSONObj();
            params.bounds.endKeyInclusive = true;
            params.direction = 1;
            IndexScan* secondScan = new IndexScan(params, &ws, NULL);

            // Second child of the AND_HASH stage is a Fetch. The NULL in the
            // constructor means there is no filter.
            FetchStage* fetch = new FetchStage(&ws, secondScan, NULL);
            ah->addChild(fetch);

            // Check that the AndHash stage returns docs {foo: 10, bar: 10}
            // through {foo: 20, bar: 20}.
            for (int i = 10; i <= 20; i++) {
                BSONObj obj = getNext(ah.get(), &ws);
                ASSERT_EQUALS(i, obj["foo"].numberInt());
                ASSERT_EQUALS(i, obj["bar"].numberInt());
            }
        }
    };


    //
    // Sorted AND tests
    //

    /**
     * Invalidate a DiskLoc held by a sorted AND before the AND finishes evaluating.  The AND should
     * process all other data just fine and flag the invalidated DiskLoc in the WorkingSet.
     */
    class QueryStageAndSortedInvalidation : public QueryStageAndBase {
    public:
        void run() {
            Client::WriteContext ctx(ns());
            Database* db = ctx.ctx().db();
            Collection* coll = db->getCollection(ns());
            if (!coll) {
                coll = db->createCollection(ns());
            }

            // Insert a bunch of data
            for (int i = 0; i < 50; ++i) {
                insert(BSON("foo" << 1 << "bar" << 1));
            }
            addIndex(BSON("foo" << 1));
            addIndex(BSON("bar" << 1));

            WorkingSet ws;
            scoped_ptr<AndSortedStage> ah(new AndSortedStage(&ws, NULL));

            // Scan over foo == 1
            IndexScanParams params;
            params.descriptor = getIndex(BSON("foo" << 1), coll);
            params.bounds.isSimpleRange = true;
            params.bounds.startKey = BSON("" << 1);
            params.bounds.endKey = BSON("" << 1);
            params.bounds.endKeyInclusive = true;
            params.direction = 1;
            ah->addChild(new IndexScan(params, &ws, NULL));

            // Scan over bar == 1
            params.descriptor = getIndex(BSON("bar" << 1), coll);
            ah->addChild(new IndexScan(params, &ws, NULL));

            // Get the set of disklocs in our collection to use later.
            set<DiskLoc> data;
            getLocs(&data, coll);

            // We're making an assumption here that happens to be true because we clear out the
            // collection before running this: increasing inserts have increasing DiskLocs.
            // This isn't true in general if the collection is not dropped beforehand.
            WorkingSetID id = WorkingSet::INVALID_ID;

            // Sorted AND looks at the first child, which is an index scan over foo==1.
            ah->work(&id);

            // The first thing that the index scan returns (due to increasing DiskLoc trick) is the
            // very first insert, which should be the very first thing in data.  Let's invalidate it
            // and make sure it shows up in the flagged results.
            ah->prepareToYield();
            ah->invalidate(*data.begin(), INVALIDATION_DELETION);
            remove(data.begin()->obj());
            ah->recoverFromYield();

            // Make sure the nuked obj is actually in the flagged data.
            ASSERT_EQUALS(ws.getFlagged().size(), size_t(1));
            WorkingSetMember* member = ws.get(*ws.getFlagged().begin());
            ASSERT_EQUALS(WorkingSetMember::OWNED_OBJ, member->state);
            BSONElement elt;
            ASSERT_TRUE(member->getFieldDotted("foo", &elt));
            ASSERT_EQUALS(1, elt.numberInt());
            ASSERT_TRUE(member->getFieldDotted("bar", &elt));
            ASSERT_EQUALS(1, elt.numberInt());

            set<DiskLoc>::iterator it = data.begin();

            // Proceed along, AND-ing results.
            int count = 0;
            while (!ah->isEOF() && count < 10) {
                WorkingSetID id = WorkingSet::INVALID_ID;
                PlanStage::StageState status = ah->work(&id);
                if (PlanStage::ADVANCED != status) { continue; }

                ++count;
                ++it;
                member = ws.get(id);

                ASSERT_TRUE(member->getFieldDotted("foo", &elt));
                ASSERT_EQUALS(1, elt.numberInt());
                ASSERT_TRUE(member->getFieldDotted("bar", &elt));
                ASSERT_EQUALS(1, elt.numberInt());
                ASSERT_EQUALS(member->loc, *it);
            }

            // Move 'it' to a result that's yet to show up.
            for (int i = 0; i < count + 10; ++i) { ++it; }
            // Remove a result that's coming up.  It's not the 'target' result of the AND so it's
            // not flagged.
            ah->prepareToYield();
            ah->invalidate(*it, INVALIDATION_DELETION);
            remove(it->obj());
            ah->recoverFromYield();

            // Get all results aside from the two we killed.
            while (!ah->isEOF()) {
                WorkingSetID id = WorkingSet::INVALID_ID;
                PlanStage::StageState status = ah->work(&id);
                if (PlanStage::ADVANCED != status) { continue; }

                ++count;
                member = ws.get(id);

                ASSERT_TRUE(member->getFieldDotted("foo", &elt));
                ASSERT_EQUALS(1, elt.numberInt());
                ASSERT_TRUE(member->getFieldDotted("bar", &elt));
                ASSERT_EQUALS(1, elt.numberInt());
            }

            ASSERT_EQUALS(count, 48);

            ASSERT_EQUALS(size_t(1), ws.getFlagged().size());
        }
    };


    // An AND with three children.
    class QueryStageAndSortedThreeLeaf : public QueryStageAndBase {
    public:
        void run() {
            Client::WriteContext ctx(ns());
            Database* db = ctx.ctx().db();
            Collection* coll = db->getCollection(ns());
            if (!coll) {
                coll = db->createCollection(ns());
            }

            // Insert a bunch of data
            for (int i = 0; i < 50; ++i) {
                // Some data that'll show up but not be in all.
                insert(BSON("foo" << 1 << "baz" << 1));
                insert(BSON("foo" << 1 << "bar" << 1));
                // The needle in the haystack.  Only these should be returned by the AND.
                insert(BSON("foo" << 1 << "bar" << 1 << "baz" << 1));
                insert(BSON("foo" << 1));
                insert(BSON("bar" << 1));
                insert(BSON("baz" << 1));
            }

            addIndex(BSON("foo" << 1));
            addIndex(BSON("bar" << 1));
            addIndex(BSON("baz" << 1));

            WorkingSet ws;
            scoped_ptr<AndSortedStage> ah(new AndSortedStage(&ws, NULL));

            // Scan over foo == 1
            IndexScanParams params;
            params.descriptor = getIndex(BSON("foo" << 1), coll);
            params.bounds.isSimpleRange = true;
            params.bounds.startKey = BSON("" << 1);
            params.bounds.endKey = BSON("" << 1);
            params.bounds.endKeyInclusive = true;
            params.direction = 1;
            ah->addChild(new IndexScan(params, &ws, NULL));

            // bar == 1
            params.descriptor = getIndex(BSON("bar" << 1), coll);
            ah->addChild(new IndexScan(params, &ws, NULL));

            // baz == 1
            params.descriptor = getIndex(BSON("baz" << 1), coll);
            ah->addChild(new IndexScan(params, &ws, NULL));

            ASSERT_EQUALS(50, countResults(ah.get()));
        }
    };

    // An AND with an index scan that returns nothing.
    class QueryStageAndSortedWithNothing : public QueryStageAndBase {
    public:
        void run() {
            Client::WriteContext ctx(ns());
            Database* db = ctx.ctx().db();
            Collection* coll = db->getCollection(ns());
            if (!coll) {
                coll = db->createCollection(ns());
            }


            for (int i = 0; i < 50; ++i) {
                insert(BSON("foo" << 8 << "bar" << 20));
            }

            addIndex(BSON("foo" << 1));
            addIndex(BSON("bar" << 1));

            WorkingSet ws;
            scoped_ptr<AndSortedStage> ah(new AndSortedStage(&ws, NULL));

            // Foo == 7.  Should be EOF.
            IndexScanParams params;
            params.descriptor = getIndex(BSON("foo" << 1), coll);
            params.bounds.isSimpleRange = true;
            params.bounds.startKey = BSON("" << 7);
            params.bounds.endKey = BSON("" << 7);
            params.bounds.endKeyInclusive = true;
            params.direction = 1;
            ah->addChild(new IndexScan(params, &ws, NULL));

            // Bar == 20, not EOF.
            params.descriptor = getIndex(BSON("bar" << 1), coll);
            params.bounds.startKey = BSON("" << 20);
            params.bounds.endKey = BSON("" << 20);
            params.bounds.endKeyInclusive = true;
            params.direction = 1;
            ah->addChild(new IndexScan(params, &ws, NULL));

            ASSERT_EQUALS(0, countResults(ah.get()));
        }
    };

    // An AND that scans data but returns nothing.
    class QueryStageAndSortedProducesNothing : public QueryStageAndBase {
    public:
        void run() {
            Client::WriteContext ctx(ns());
            Database* db = ctx.ctx().db();
            Collection* coll = db->getCollection(ns());
            if (!coll) {
                coll = db->createCollection(ns());
            }

            for (int i = 0; i < 50; ++i) {
                // Insert data with foo=7, bar==20, but nothing with both.
                insert(BSON("foo" << 8 << "bar" << 20));
                insert(BSON("foo" << 7 << "bar" << 21));
                insert(BSON("foo" << 7));
                insert(BSON("bar" << 20));
            }

            addIndex(BSON("foo" << 1));
            addIndex(BSON("bar" << 1));

            WorkingSet ws;
            scoped_ptr<AndSortedStage> ah(new AndSortedStage(&ws, NULL));

            // foo == 7.
            IndexScanParams params;
            params.descriptor = getIndex(BSON("foo" << 1), coll);
            params.bounds.isSimpleRange = true;
            params.bounds.startKey = BSON("" << 7);
            params.bounds.endKey = BSON("" << 7);
            params.bounds.endKeyInclusive = true;
            params.direction = 1;
            ah->addChild(new IndexScan(params, &ws, NULL));

            // bar == 20.
            params.descriptor = getIndex(BSON("bar" << 1), coll);
            params.bounds.startKey = BSON("" << 20);
            params.bounds.endKey = BSON("" << 20);
            params.bounds.endKeyInclusive = true;
            params.direction = 1;
            ah->addChild(new IndexScan(params, &ws, NULL));

            ASSERT_EQUALS(0, countResults(ah.get()));
        }
    };

    // An AND that would return data but the matcher prevents it.
    class QueryStageAndSortedWithMatcher : public QueryStageAndBase {
    public:
        void run() {
            Client::WriteContext ctx(ns());
            Database* db = ctx.ctx().db();
            Collection* coll = db->getCollection(ns());
            if (!coll) {
                coll = db->createCollection(ns());
            }

            for (int i = 0; i < 50; ++i) {
                insert(BSON("foo" << 1 << "bar" << 1));
            }

            addIndex(BSON("foo" << 1));
            addIndex(BSON("bar" << 1));

            WorkingSet ws;
            BSONObj filterObj = BSON("foo" << BSON("$ne" << 1));
            StatusWithMatchExpression swme = MatchExpressionParser::parse(filterObj);
            verify(swme.isOK());
            auto_ptr<MatchExpression> filterExpr(swme.getValue());
            scoped_ptr<AndSortedStage> ah(new AndSortedStage(&ws, filterExpr.get()));

            // Scan over foo == 1
            IndexScanParams params;
            params.descriptor = getIndex(BSON("foo" << 1), coll);
            params.bounds.isSimpleRange = true;
            params.bounds.startKey = BSON("" << 1);
            params.bounds.endKey = BSON("" << 1);
            params.bounds.endKeyInclusive = true;
            params.direction = 1;
            ah->addChild(new IndexScan(params, &ws, NULL));

            // bar == 1
            params.descriptor = getIndex(BSON("bar" << 1), coll);
            ah->addChild(new IndexScan(params, &ws, NULL));

            // Filter drops everything.
            ASSERT_EQUALS(0, countResults(ah.get()));
        }
    };

    // Verify that AND preserves the order of the last child.
    class QueryStageAndSortedByLastChild : public QueryStageAndBase {
    public:
        void run() {
            Client::WriteContext ctx(ns());
            Database* db = ctx.ctx().db();
            Collection* coll = db->getCollection(ns());
            if (!coll) {
                coll = db->createCollection(ns());
            }

            for (int i = 0; i < 50; ++i) {
                insert(BSON("foo" << 1 << "bar" << i));
            }

            addIndex(BSON("foo" << 1));
            addIndex(BSON("bar" << 1));

            WorkingSet ws;
            scoped_ptr<AndHashStage> ah(new AndHashStage(&ws, NULL));

            // Scan over foo == 1
            IndexScanParams params;
            params.descriptor = getIndex(BSON("foo" << 1), coll);
            params.bounds.isSimpleRange = true;
            params.bounds.startKey = BSON("" << 1);
            params.bounds.endKey = BSON("" << 1);
            params.bounds.endKeyInclusive = true;
            params.direction = 1;
            ah->addChild(new IndexScan(params, &ws, NULL));

            // Intersect with 7 <= bar < 10000
            params.descriptor = getIndex(BSON("bar" << 1), coll);
            params.bounds.startKey = BSON("" << 7);
            params.bounds.endKey = BSON("" << 10000);
            ah->addChild(new IndexScan(params, &ws, NULL));

            WorkingSetID lastId = WorkingSet::INVALID_ID;

            int count = 0;
            while (!ah->isEOF()) {
                WorkingSetID id = WorkingSet::INVALID_ID;
                PlanStage::StageState status = ah->work(&id);
                if (PlanStage::ADVANCED != status) { continue; }
                BSONObj thisObj = ws.get(id)->loc.obj();
                ASSERT_EQUALS(7 + count, thisObj["bar"].numberInt());
                ++count;
                if (WorkingSet::INVALID_ID != lastId) {
                    BSONObj lastObj = ws.get(lastId)->loc.obj();
                    ASSERT_LESS_THAN(lastObj["bar"].woCompare(thisObj["bar"]), 0);
                }
                lastId = id;
            }

            ASSERT_EQUALS(count, 43);
        }
    };

    /**
     * SERVER-14607: Check that sort-based intersection works when the first
     * child returns fetched docs but the second child returns index keys.
     */
    class QueryStageAndSortedFirstChildFetched : public QueryStageAndBase {
    public:
        void run() {
            Client::WriteContext ctx(ns());
            Database* db = ctx.ctx().db();
            Collection* coll = db->getCollection(ns());
            if (!coll) {
                coll = db->createCollection(ns());
            }

            // Insert a bunch of data
            for (int i = 0; i < 50; ++i) {
                insert(BSON("foo" << 1 << "bar" << 1));
            }

            addIndex(BSON("foo" << 1));
            addIndex(BSON("bar" << 1));

            WorkingSet ws;
            scoped_ptr<AndSortedStage> as(new AndSortedStage(&ws, NULL));

            // Scan over foo == 1
            IndexScanParams params;
            params.descriptor = getIndex(BSON("foo" << 1), coll);
            params.bounds.isSimpleRange = true;
            params.bounds.startKey = BSON("" << 1);
            params.bounds.endKey = BSON("" << 1);
            params.bounds.endKeyInclusive = true;
            params.direction = 1;
            IndexScan* firstScan = new IndexScan(params, &ws, NULL);

            // First child of the AND_SORTED stage is a Fetch. The NULL in the
            // constructor means there is no filter.
            FetchStage* fetch = new FetchStage(&ws, firstScan, NULL);
            as->addChild(fetch);

            // bar == 1
            params.descriptor = getIndex(BSON("bar" << 1), coll);
            as->addChild(new IndexScan(params, &ws, NULL));

            for (int i = 0; i < 50; i++) {
                BSONObj obj = getNext(as.get(), &ws);
                ASSERT_EQUALS(1, obj["foo"].numberInt());
                ASSERT_EQUALS(1, obj["bar"].numberInt());
            }
        }
    };

    /**
     * SERVER-14607: Check that sort-based intersection works when the first
     * child returns index keys but the second returns fetched docs.
     */
    class QueryStageAndSortedSecondChildFetched : public QueryStageAndBase {
    public:
        void run() {
            Client::WriteContext ctx(ns());
            Database* db = ctx.ctx().db();
            Collection* coll = db->getCollection(ns());
            if (!coll) {
                coll = db->createCollection(ns());
            }

            // Insert a bunch of data
            for (int i = 0; i < 50; ++i) {
                insert(BSON("foo" << 1 << "bar" << 1));
            }

            addIndex(BSON("foo" << 1));
            addIndex(BSON("bar" << 1));

            WorkingSet ws;
            scoped_ptr<AndSortedStage> as(new AndSortedStage(&ws, NULL));

            // Scan over foo == 1
            IndexScanParams params;
            params.descriptor = getIndex(BSON("foo" << 1), coll);
            params.bounds.isSimpleRange = true;
            params.bounds.startKey = BSON("" << 1);
            params.bounds.endKey = BSON("" << 1);
            params.bounds.endKeyInclusive = true;
            params.direction = 1;
            as->addChild(new IndexScan(params, &ws, NULL));

            // bar == 1
            params.descriptor = getIndex(BSON("bar" << 1), coll);
            IndexScan* secondScan = new IndexScan(params, &ws, NULL);

            // Second child of the AND_SORTED stage is a Fetch. The NULL in the
            // constructor means there is no filter.
            FetchStage* fetch = new FetchStage(&ws, secondScan, NULL);
            as->addChild(fetch);

            for (int i = 0; i < 50; i++) {
                BSONObj obj = getNext(as.get(), &ws);
                ASSERT_EQUALS(1, obj["foo"].numberInt());
                ASSERT_EQUALS(1, obj["bar"].numberInt());
            }
        }
    };


    class All : public Suite {
    public:
        All() : Suite( "query_stage_and" ) { }

        void setupTests() {
            add<QueryStageAndHashInvalidation>();
            add<QueryStageAndHashTwoLeaf>();
            add<QueryStageAndHashTwoLeafFirstChildLargeKeys>();
            add<QueryStageAndHashTwoLeafLastChildLargeKeys>();
            add<QueryStageAndHashThreeLeaf>();
            add<QueryStageAndHashThreeLeafMiddleChildLargeKeys>();
            add<QueryStageAndHashWithNothing>();
            add<QueryStageAndHashProducesNothing>();
            add<QueryStageAndHashWithMatcher>();
            add<QueryStageAndHashInvalidateLookahead>();
            add<QueryStageAndHashFirstChildFetched>();
            add<QueryStageAndHashSecondChildFetched>();
            add<QueryStageAndSortedInvalidation>();
            add<QueryStageAndSortedThreeLeaf>();
            add<QueryStageAndSortedWithNothing>();
            add<QueryStageAndSortedProducesNothing>();
            add<QueryStageAndSortedWithMatcher>();
            add<QueryStageAndSortedByLastChild>();
            add<QueryStageAndSortedFirstChildFetched>();
            add<QueryStageAndSortedSecondChildFetched>();
        }
    }  queryStageAndAll;

}  // namespace QueryStageAnd
