SERVER-32189 Delete dead SubplanStage handling for contained $or queries.

3 files changed, 2 insertions, 196 deletions

diff --git a/src/mongo/db/exec/subplan.cpp b/src/mongo/db/exec/subplan.cpp
index f8b30a6a7a3..0d3ee99ffc4 100644
--- a/src/mongo/db/exec/subplan.cpp
+++ b/src/mongo/db/exec/subplan.cpp
@@ -71,30 +71,9 @@ SubplanStage::SubplanStage(OperationContext* opCtx,
       _plannerParams(params),
       _query(cq) {
     invariant(_collection);
+    invariant(_query->root()->matchType() == MatchExpression::OR);
 }
 
-namespace {
-
-/**
- * Returns true if 'expr' is an AND that contains a single OR child.
- */
-bool isContainedOr(const MatchExpression* expr) {
-    if (MatchExpression::AND != expr->matchType()) {
-        return false;
-    }
-
-    size_t numOrs = 0;
-    for (size_t i = 0; i < expr->numChildren(); ++i) {
-        if (MatchExpression::OR == expr->getChild(i)->matchType()) {
-            ++numOrs;
-        }
-    }
-
-    return (numOrs == 1U);
-}
-
-}  // namespace
-
 bool SubplanStage::canUseSubplanning(const CanonicalQuery& query) {
     const QueryRequest& qr = query.getQueryRequest();
     const MatchExpression* expr = query.root();
@@ -126,54 +105,12 @@ bool SubplanStage::canUseSubplanning(const CanonicalQuery& query) {
         return false;
     }
 
-    // TODO: For now we only allow rooted OR. We should consider also allowing contained OR that
-    // does not have a TEXT or GEO_NEAR node.
+    // We can only subplan rooted $or queries.
     return MatchExpression::OR == expr->matchType();
 }
 
-std::unique_ptr<MatchExpression> SubplanStage::rewriteToRootedOr(
-    std::unique_ptr<MatchExpression> root) {
-    dassert(isContainedOr(root.get()));
-
-    // Detach the OR from the root.
-    std::vector<MatchExpression*>& rootChildren = *root->getChildVector();
-    std::unique_ptr<MatchExpression> orChild;
-    for (size_t i = 0; i < rootChildren.size(); ++i) {
-        if (MatchExpression::OR == rootChildren[i]->matchType()) {
-            orChild.reset(rootChildren[i]);
-            rootChildren.erase(rootChildren.begin() + i);
-            break;
-        }
-    }
-
-    // We should have found an OR, and the OR should have at least 2 children.
-    invariant(orChild);
-    invariant(orChild->getChildVector());
-    invariant(orChild->getChildVector()->size() > 1U);
-
-    // AND the existing root with each OR child.
-    std::vector<MatchExpression*>& orChildren = *orChild->getChildVector();
-    for (size_t i = 0; i < orChildren.size(); ++i) {
-        std::unique_ptr<AndMatchExpression> ama = stdx::make_unique<AndMatchExpression>();
-        ama->add(orChildren[i]);
-        ama->add(root->shallowClone().release());
-        orChildren[i] = ama.release();
-    }
-
-    // Normalize and sort the resulting match expression.
-    orChild = MatchExpression::optimize(std::move(orChild));
-    CanonicalQuery::sortTree(orChild.get());
-
-    return orChild;
-}
-
 Status SubplanStage::planSubqueries() {
     _orExpression = _query->root()->shallowClone();
-    if (isContainedOr(_orExpression.get())) {
-        _orExpression = rewriteToRootedOr(std::move(_orExpression));
-        invariant(CanonicalQuery::isValid(_orExpression.get(), _query->getQueryRequest()).isOK());
-    }
-
     for (size_t i = 0; i < _plannerParams.indices.size(); ++i) {
         const IndexEntry& ie = _plannerParams.indices[i];
         _indexMap[ie.name] = i;
diff --git a/src/mongo/db/exec/subplan.h b/src/mongo/db/exec/subplan.h
index 315e79b93ca..c61fb3201d4 100644
--- a/src/mongo/db/exec/subplan.h
+++ b/src/mongo/db/exec/subplan.h
@@ -107,19 +107,6 @@ public:
      */
     Status pickBestPlan(PlanYieldPolicy* yieldPolicy);
 
-    /**
-     * Takes a match expression, 'root', which has a single "contained OR". This means that
-     * 'root' is an AND with exactly one OR child.
-     *
-     * Returns a logically equivalent query after rewriting so that the contained OR is at the
-     * root of the expression tree.
-     *
-     * Used internally so that the subplanner can be used for contained OR type queries, but
-     * exposed for testing.
-     */
-    static std::unique_ptr<MatchExpression> rewriteToRootedOr(
-        std::unique_ptr<MatchExpression> root);
-
     //
     // For testing.
     //
diff --git a/src/mongo/dbtests/query_stage_subplan.cpp b/src/mongo/dbtests/query_stage_subplan.cpp
index 279eafac9c7..c15f0fc6e71 100644
--- a/src/mongo/dbtests/query_stage_subplan.cpp
+++ b/src/mongo/dbtests/query_stage_subplan.cpp
@@ -402,8 +402,6 @@ TEST_F(QueryStageSubplanTest, QueryStageSubplanCanUseSubplanning) {
     }
 
     // Can't use subplanning for a single contained $or.
-    //
-    // TODO: Consider allowing this to use subplanning (see SERVER-13732).
     {
         std::string findCmd =
             "{find: 'testns',"
@@ -413,8 +411,6 @@ TEST_F(QueryStageSubplanTest, QueryStageSubplanCanUseSubplanning) {
     }
 
     // Can't use subplanning if the contained $or query has a geo predicate.
-    //
-    // TODO: Consider allowing this to use subplanning (see SERVER-13732).
     {
         std::string findCmd =
             "{find: 'testns',"
@@ -446,120 +442,6 @@ TEST_F(QueryStageSubplanTest, QueryStageSubplanCanUseSubplanning) {
 }
 
 /**
- * Unit test the subplan stage's rewriteToRootedOr() method.
- */
-TEST_F(QueryStageSubplanTest, QueryStageSubplanRewriteToRootedOr) {
-    // Rewrite (AND (OR a b) e) => (OR (AND a e) (AND b e))
-    {
-        BSONObj queryObj = fromjson("{$or:[{a:1}, {b:1}], e:1}");
-        boost::intrusive_ptr<ExpressionContextForTest> expCtx(new ExpressionContextForTest());
-        StatusWithMatchExpression expr = MatchExpressionParser::parse(queryObj, expCtx);
-        ASSERT_OK(expr.getStatus());
-        std::unique_ptr<MatchExpression> rewrittenExpr =
-            SubplanStage::rewriteToRootedOr(std::move(expr.getValue()));
-
-        std::string findCmdRewritten =
-            "{find: 'testns',"
-            "filter: {$or:[{a:1,e:1}, {b:1,e:1}]}}";
-        std::unique_ptr<CanonicalQuery> cqRewritten = cqFromFindCommand(findCmdRewritten);
-
-        ASSERT(rewrittenExpr->equivalent(cqRewritten->root()));
-    }
-
-    // Rewrite (AND (OR a b) e f) => (OR (AND a e f) (AND b e f))
-    {
-        BSONObj queryObj = fromjson("{$or:[{a:1}, {b:1}], e:1, f:1}");
-        boost::intrusive_ptr<ExpressionContextForTest> expCtx(new ExpressionContextForTest());
-        StatusWithMatchExpression expr = MatchExpressionParser::parse(queryObj, expCtx);
-        ASSERT_OK(expr.getStatus());
-        std::unique_ptr<MatchExpression> rewrittenExpr =
-            SubplanStage::rewriteToRootedOr(std::move(expr.getValue()));
-
-        std::string findCmdRewritten =
-            "{find: 'testns',"
-            "filter: {$or:[{a:1,e:1,f:1}, {b:1,e:1,f:1}]}}";
-        std::unique_ptr<CanonicalQuery> cqRewritten = cqFromFindCommand(findCmdRewritten);
-
-        ASSERT(rewrittenExpr->equivalent(cqRewritten->root()));
-    }
-
-    // Rewrite (AND (OR (AND a b) (AND c d) e f) => (OR (AND a b e f) (AND c d e f))
-    {
-        BSONObj queryObj = fromjson("{$or:[{a:1,b:1}, {c:1,d:1}], e:1,f:1}");
-        boost::intrusive_ptr<ExpressionContextForTest> expCtx(new ExpressionContextForTest());
-        StatusWithMatchExpression expr = MatchExpressionParser::parse(queryObj, expCtx);
-        ASSERT_OK(expr.getStatus());
-        std::unique_ptr<MatchExpression> rewrittenExpr =
-            SubplanStage::rewriteToRootedOr(std::move(expr.getValue()));
-
-        std::string findCmdRewritten =
-            "{find: 'testns',"
-            "filter: {$or:[{a:1,b:1,e:1,f:1},"
-            "{c:1,d:1,e:1,f:1}]}}";
-        std::unique_ptr<CanonicalQuery> cqRewritten = cqFromFindCommand(findCmdRewritten);
-
-        ASSERT(rewrittenExpr->equivalent(cqRewritten->root()));
-    }
-}
-
-/**
- * Test the subplan stage's ability to answer a contained $or query.
- */
-TEST_F(QueryStageSubplanTest, QueryStageSubplanPlanContainedOr) {
-    OldClientWriteContext ctx(opCtx(), nss.ns());
-    addIndex(BSON("b" << 1 << "a" << 1));
-    addIndex(BSON("c" << 1 << "a" << 1));
-
-    BSONObj query = fromjson("{a: 1, $or: [{b: 2}, {c: 3}]}");
-
-    // Two of these documents match.
-    insert(BSON("_id" << 1 << "a" << 1 << "b" << 2));
-    insert(BSON("_id" << 2 << "a" << 2 << "b" << 2));
-    insert(BSON("_id" << 3 << "a" << 1 << "c" << 3));
-    insert(BSON("_id" << 4 << "a" << 1 << "c" << 4));
-
-    auto qr = stdx::make_unique<QueryRequest>(nss);
-    qr->setFilter(query);
-    auto cq = unittest::assertGet(CanonicalQuery::canonicalize(opCtx(), std::move(qr)));
-
-    Collection* collection = ctx.getCollection();
-
-    // Get planner params.
-    QueryPlannerParams plannerParams;
-    fillOutPlannerParams(opCtx(), collection, cq.get(), &plannerParams);
-
-    WorkingSet ws;
-    std::unique_ptr<SubplanStage> subplan(
-        new SubplanStage(opCtx(), collection, &ws, plannerParams, cq.get()));
-
-    // Plan selection should succeed due to falling back on regular planning.
-    PlanYieldPolicy yieldPolicy(PlanExecutor::NO_YIELD, _clock);
-    ASSERT_OK(subplan->pickBestPlan(&yieldPolicy));
-
-    // Work the stage until it produces all results.
-    size_t numResults = 0;
-    PlanStage::StageState stageState = PlanStage::NEED_TIME;
-    while (stageState != PlanStage::IS_EOF) {
-        WorkingSetID id = WorkingSet::INVALID_ID;
-        stageState = subplan->work(&id);
-        ASSERT_NE(stageState, PlanStage::DEAD);
-        ASSERT_NE(stageState, PlanStage::FAILURE);
-
-        if (stageState == PlanStage::ADVANCED) {
-            ++numResults;
-            WorkingSetMember* member = ws.get(id);
-            ASSERT(member->hasObj());
-            ASSERT(SimpleBSONObjComparator::kInstance.evaluate(
-                       member->obj.value() == BSON("_id" << 1 << "a" << 1 << "b" << 2)) ||
-                   SimpleBSONObjComparator::kInstance.evaluate(
-                       member->obj.value() == BSON("_id" << 3 << "a" << 1 << "c" << 3)));
-        }
-    }
-
-    ASSERT_EQ(numResults, 2U);
-}
-
-/**
  * Test the subplan stage's ability to answer a rooted $or query with a $ne and a sort.
  *
  * Regression test for SERVER-19388.