SERVER-65665 Disallow the use of indexes with partial filter expressions in INLJ (cherry picked from commit b02798f3032ff6df56a45b4bcb9296b247c37be4)

2 files changed, 11 insertions, 1 deletions

diff --git a/jstests/noPassthrough/lookup_pushdown.js b/jstests/noPassthrough/lookup_pushdown.js
index 1f91a4abecf..b14ab066437 100644
--- a/jstests/noPassthrough/lookup_pushdown.js
+++ b/jstests/noPassthrough/lookup_pushdown.js
@@ -306,6 +306,16 @@ function setLookupPushdownDisabled(value) {
     assert.commandWorked(foreignColl.dropIndexes());
 })();
 
+// Construct an index with a partial filter expression. In this case, we should NOT use INLJ.
+(function testPartialFilterExpressionIndexesAreIgnored() {
+    assert.commandWorked(foreignColl.dropIndexes());
+    assert.commandWorked(foreignColl.createIndex({b: 1}, {partialFilterExpression: {b: 1}}));
+    runTest(coll,
+            [{$lookup: {from: foreignCollName, localField: "a", foreignField: "b", as: "out"}}],
+            JoinAlgorithm.NLJ /* expectedJoinAlgorithm */);
+    assert.commandWorked(foreignColl.dropIndexes());
+})();
+
 // Build a hashed index on the foreign collection that matches the foreignField. Indexed nested loop
 // join strategy should be used.
 (function testIndexNestedLoopJoinHashedIndex() {
diff --git a/src/mongo/db/query/planner_analysis.cpp b/src/mongo/db/query/planner_analysis.cpp
index 654fa0f56ca..af4777dc0e2 100644
--- a/src/mongo/db/query/planner_analysis.cpp
+++ b/src/mongo/db/query/planner_analysis.cpp
@@ -662,7 +662,7 @@ void QueryPlannerAnalysis::determineLookupStrategy(
             if ((index.type == INDEX_BTREE || index.type == INDEX_HASHED) &&
                 index.keyPattern.firstElement().fieldName() ==
                     eqLookupNode->joinFieldForeign.fullPath() &&
-                CollatorInterface::collatorsMatch(collator, index.collator)) {
+                !index.filterExpr && CollatorInterface::collatorsMatch(collator, index.collator)) {
                 return index;
             }
         }