SERVER-21011 Fix query correctness problem related to covered matching for 2d/text indexes.

The fix ensures that the tightness predicates over the
trailing fields of 2d/text indexes is checked. Predicates
which are INEXACT_FETCH will then get affixed to the FETCH
stage of the plan rather than incorrectly affixed to the
IXSCAN.

1 files changed, 50 insertions, 0 deletions

diff --git a/src/mongo/db/query/index_bounds_builder_test.cpp b/src/mongo/db/query/index_bounds_builder_test.cpp
index f7d0e23794e..264972d017f 100644
--- a/src/mongo/db/query/index_bounds_builder_test.cpp
+++ b/src/mongo/db/query/index_bounds_builder_test.cpp
@@ -2209,4 +2209,54 @@ TEST(IndexBoundsBuilderTest, RedundantTypeNumberHasCorrectBounds) {
     ASSERT(tightness == IndexBoundsBuilder::INEXACT_FETCH);
 }
 
+TEST(IndexBoundsBuilderTest, CanUseCoveredMatchingForEqualityPredicate) {
+    IndexEntry testIndex = IndexEntry(BSONObj());
+    BSONObj obj = fromjson("{a: {$eq: 3}}");
+    unique_ptr<MatchExpression> expr(parseMatchExpression(obj));
+    ASSERT_TRUE(IndexBoundsBuilder::canUseCoveredMatching(expr.get(), testIndex));
+}
+
+TEST(IndexBoundsBuilderTest, CannotUseCoveredMatchingForEqualityToArrayPredicate) {
+    IndexEntry testIndex = IndexEntry(BSONObj());
+    BSONObj obj = fromjson("{a: {$eq: [1, 2, 3]}}");
+    unique_ptr<MatchExpression> expr(parseMatchExpression(obj));
+    ASSERT_FALSE(IndexBoundsBuilder::canUseCoveredMatching(expr.get(), testIndex));
+}
+
+TEST(IndexBoundsBuilderTest, CannotUseCoveredMatchingForEqualityToNullPredicate) {
+    IndexEntry testIndex = IndexEntry(BSONObj());
+    BSONObj obj = fromjson("{a: null}");
+    unique_ptr<MatchExpression> expr(parseMatchExpression(obj));
+    ASSERT_FALSE(IndexBoundsBuilder::canUseCoveredMatching(expr.get(), testIndex));
+}
+
+TEST(IndexBoundsBuilderTest, CannotUseCoveredMatchingForTypeArrayPredicate) {
+    IndexEntry testIndex = IndexEntry(BSONObj());
+    BSONObj obj = fromjson("{a: {$type: 'array'}}");
+    unique_ptr<MatchExpression> expr(parseMatchExpression(obj));
+    ASSERT_FALSE(IndexBoundsBuilder::canUseCoveredMatching(expr.get(), testIndex));
+}
+
+TEST(IndexBoundsBuilderTest, CannotUseCoveredMatchingForExistsTruePredicate) {
+    IndexEntry testIndex = IndexEntry(BSONObj());
+    BSONObj obj = fromjson("{a: {$exists: true}}");
+    unique_ptr<MatchExpression> expr(parseMatchExpression(obj));
+    ASSERT_FALSE(IndexBoundsBuilder::canUseCoveredMatching(expr.get(), testIndex));
+}
+
+TEST(IndexBoundsBuilderTest, CannotUseCoveredMatchingForExistsFalsePredicate) {
+    IndexEntry testIndex = IndexEntry(BSONObj());
+    BSONObj obj = fromjson("{a: {$exists: false}}");
+    unique_ptr<MatchExpression> expr(parseMatchExpression(obj));
+    ASSERT_FALSE(IndexBoundsBuilder::canUseCoveredMatching(expr.get(), testIndex));
+}
+
+TEST(IndexBoundsBuilderTest, CanUseCoveredMatchingForExistsTrueWithSparseIndex) {
+    IndexEntry testIndex = IndexEntry(BSONObj());
+    testIndex.sparse = true;
+    BSONObj obj = fromjson("{a: {$exists: true}}");
+    unique_ptr<MatchExpression> expr(parseMatchExpression(obj));
+    ASSERT_TRUE(IndexBoundsBuilder::canUseCoveredMatching(expr.get(), testIndex));
+}
+
 }  // namespace