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author | James Wahlin <james@mongodb.com> | 2020-12-08 11:39:25 -0500 |
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committer | Evergreen Agent <no-reply@evergreen.mongodb.com> | 2020-12-08 23:25:34 +0000 |
commit | ab521227f18b94f546fa3e23d99de4b080739a9c (patch) | |
tree | 8770303942a900b7a74e4f1000abbb72bd1248c4 | |
parent | f3e9474a1482f4de4454480150ec77139c6e626f (diff) | |
download | mongo-ab521227f18b94f546fa3e23d99de4b080739a9c.tar.gz |
SERVER-52618
-rw-r--r-- | jstests/core/hashed_partial_and_sparse_index.js | 93 | ||||
-rw-r--r-- | src/mongo/db/query/planner_ixselect.cpp | 33 | ||||
-rw-r--r-- | src/mongo/db/query/planner_ixselect_test.cpp | 28 |
3 files changed, 147 insertions, 7 deletions
diff --git a/jstests/core/hashed_partial_and_sparse_index.js b/jstests/core/hashed_partial_and_sparse_index.js new file mode 100644 index 00000000000..2e412ce1b0c --- /dev/null +++ b/jstests/core/hashed_partial_and_sparse_index.js @@ -0,0 +1,93 @@ +/** + * Tests to verify that the queries return correct results in the presence of partial hashed + * index and sparse index. + * @tags: [ + * requires_fcv_42, + * ] + */ +(function() { +"use strict"; + +load("jstests/aggregation/extras/utils.js"); // For arrayEq(). +load("jstests/libs/analyze_plan.js"); // For assertStagesForExplainOfCommand(). + +const coll = db.hashed_partial_index; +coll.drop(); +assert.commandWorked(coll.insert({})); +assert.commandWorked(coll.insert({a: null})); +assert.commandWorked(coll.insert({a: 1})); +assert.commandWorked(coll.insert({b: 4})); +assert.commandWorked(coll.insert({a: 1, b: 6})); + +/** + * Runs explain() operation on 'cmdObj' and verifies that all the stages in 'expectedStages' are + * present exactly once in the plan returned. When 'stagesNotExpected' array is passed, also + * verifies that none of those stages are present in the explain() plan. + */ +function assertStagesForExplainOfCommand({coll, cmdObj, expectedStages, stagesNotExpected}) { + const plan = assert.commandWorked(coll.runCommand({explain: cmdObj})); + const winningPlan = plan.queryPlanner.winningPlan; + for (let expectedStage of expectedStages) { + assert(planHasStage(coll.getDB(), winningPlan, expectedStage), + "Could not find stage " + expectedStage + ". Plan: " + tojson(plan)); + } + for (let stage of (stagesNotExpected || [])) { + assert(!planHasStage(coll.getDB(), winningPlan, stage), + "Found stage " + stage + " when not expected. Plan: " + tojson(plan)); + } + return plan; +} + +/** + * Runs find command with the 'filter' and validates that the output returned matches + * 'expectedOutput'. Also runs explain() command on the same find command and validates that all + * the 'expectedStages' are present in the plan returned. + */ +function validateFindCmdOutputAndPlan({filter, expectedStages, expectedOutput}) { + const cmdObj = {find: coll.getName(), filter: filter, projection: {_id: 0}}; + if (expectedOutput) { + const res = assert.commandWorked(coll.runCommand(cmdObj)); + const ouputArray = new DBCommandCursor(coll.getDB(), res).toArray(); + + // We ignore the order since hashed index order is not predictable. + assert(arrayEq(expectedOutput, ouputArray), ouputArray); + } + assertStagesForExplainOfCommand({coll: coll, cmdObj: cmdObj, expectedStages: expectedStages}); +} + +function testSparseHashedIndex(indexSpec) { + assert.commandWorked(coll.dropIndexes()); + assert.commandWorked(coll.createIndex(indexSpec, {sparse: true})); + + // Verify index not used for null/missing queries with sparse index. + validateFindCmdOutputAndPlan({filter: {a: null}, expectedStages: ["COLLSCAN"]}); + validateFindCmdOutputAndPlan({filter: {a: {$exists: false}}, expectedStages: ["COLLSCAN"]}); + + // Test {$exists: false} when hashed field is not a prefix and index is sparse. + validateFindCmdOutputAndPlan({ + filter: {a: {$exists: false}}, + expectedOutput: [{b: 4}, {}], + expectedStages: ["COLLSCAN"], + stagesNotExpected: ["IXSCAN"] + }); +} + +/** + * Test sparse indexes with hashed prefix. + */ +testSparseHashedIndex({a: "hashed"}); + +/** + * Tests for partial indexes. + */ +assert.commandWorked(coll.dropIndexes()); +assert.commandWorked(coll.createIndex({b: "hashed"}, {partialFilterExpression: {b: {$gt: 5}}})); + +// Verify that index is not used if the query predicate doesn't match the +// 'partialFilterExpression'. +validateFindCmdOutputAndPlan({filter: {b: 4}, expectedStages: ["COLLSCAN"]}); + +// Verify that index is used if the query predicate matches the 'partialFilterExpression'. +validateFindCmdOutputAndPlan( + {filter: {b: 6}, expectedOutput: [{a: 1, b: 6}], expectedStages: ["IXSCAN", "FETCH"]}); +})(); diff --git a/src/mongo/db/query/planner_ixselect.cpp b/src/mongo/db/query/planner_ixselect.cpp index 685e1485cc9..60e83488d8a 100644 --- a/src/mongo/db/query/planner_ixselect.cpp +++ b/src/mongo/db/query/planner_ixselect.cpp @@ -526,6 +526,10 @@ bool QueryPlannerIXSelect::_compatible(const BSONElement& keyPatternElt, // above. MONGO_UNREACHABLE; } else if (IndexNames::HASHED == indexedFieldType) { + if (index.sparse && !nodeIsSupportedBySparseIndex(node, isChildOfElemMatchValue)) { + return false; + } + if (ComparisonMatchExpressionBase::isEquality(exprtype)) { return true; } @@ -600,11 +604,6 @@ bool QueryPlannerIXSelect::nodeIsSupportedBySparseIndex(const MatchExpression* q // cannot answer), so this function only needs to check if the query performs an equality to // null. - // Equality to null inside an $elemMatch implies a match on literal 'null'. - if (isInElemMatch) { - return true; - } - // Otherwise, we can't use a sparse index for $eq (or $lte, or $gte) with a null element. // // We can use a sparse index for $_internalExprEq with a null element. Expression language @@ -613,10 +612,30 @@ bool QueryPlannerIXSelect::nodeIsSupportedBySparseIndex(const MatchExpression* q const auto typ = queryExpr->matchType(); if (typ == MatchExpression::EQ) { const auto* queryExprEquality = static_cast<const EqualityMatchExpression*>(queryExpr); - return !queryExprEquality->getData().isNull(); + // Equality to null inside an $elemMatch implies a match on literal 'null'. + return isInElemMatch || !queryExprEquality->getData().isNull(); } else if (queryExpr->matchType() == MatchExpression::MATCH_IN) { const auto* queryExprIn = static_cast<const InMatchExpression*>(queryExpr); - return !queryExprIn->hasNull(); + // Equality to null inside an $elemMatch implies a match on literal 'null'. + return isInElemMatch || !queryExprIn->hasNull(); + } else if (queryExpr->matchType() == MatchExpression::NOT) { + const auto* child = queryExpr->getChild(0); + const MatchExpression::MatchType childtype = child->matchType(); + const bool isNotEqualsNull = + (childtype == MatchExpression::EQ && + static_cast<const ComparisonMatchExpression*>(child)->getData().type() == + BSONType::jstNULL); + + // Prevent negated predicates from using sparse indices. Doing so would cause us to + // miss documents which do not contain the indexed fields. The only case where we may + // use a sparse index for a negation is when the query is {$ne: null}. This is due to + // the behavior of {$eq: null} matching documents where the field does not exist OR the + // field is equal to literal null. The negation of {$eq: null} therefore matches + // documents where the field does exist AND the field is not equal to literal + // null. Since the field must exist, it is safe to use a sparse index. + if (!isNotEqualsNull) { + return false; + } } return true; diff --git a/src/mongo/db/query/planner_ixselect_test.cpp b/src/mongo/db/query/planner_ixselect_test.cpp index e1018a87944..cf30e1fc452 100644 --- a/src/mongo/db/query/planner_ixselect_test.cpp +++ b/src/mongo/db/query/planner_ixselect_test.cpp @@ -1290,6 +1290,34 @@ TEST(QueryPlannerIXSelectTest, HashedIndexShouldNotBeRelevantForNotEqualsNullPre testRateIndices("{a: {$ne: null}}", "", kSimpleCollator, {entry}, "a,a", expectedIndices); } +TEST(QueryPlannerIXSelectTest, HashedSparseIndexShouldNotBeRelevantForNotEqualsNullPredicate) { + auto entry = buildSimpleIndexEntry(BSON("a" + << "hashed")); + entry.type = IndexType::INDEX_HASHED; + entry.sparse = true; + std::set<size_t> expectedIndices = {}; + testRateIndices("{a: {$ne: null}}", "", kSimpleCollator, {entry}, "a,a", expectedIndices); +} + +TEST(QueryPlannerIXSelectTest, HashedSparseIndexShouldNotBeRelevantForEqualsNull) { + auto entry = buildSimpleIndexEntry(BSON("a" + << "hashed")); + entry.type = IndexType::INDEX_HASHED; + entry.sparse = true; + std::set<size_t> expectedIndices = {}; + testRateIndices("{a: {$eq: null}}", "", kSimpleCollator, {entry}, "a", expectedIndices); +} + +TEST(QueryPlannerIXSelectTest, HashedSparseIndexShouldNotBeRelevantForInWithNull) { + auto entry = buildSimpleIndexEntry(BSON("a" + << "hashed")); + entry.type = IndexType::INDEX_HASHED; + entry.sparse = true; + std::set<size_t> expectedIndices = {}; + // A non-null value must be included as well to prevent rewrite to {$eq: null}. + testRateIndices("{a: {$in: [1, null]}}", "", kSimpleCollator, {entry}, "a", expectedIndices); +} + /* * Will compare 'keyPatterns' with 'entries'. As part of comparing, it will sort both of them. */ |