SERVER-38164 $or pushdown optimization does not correctly handle $not within an $elemMatch

(cherry picked from commit 94d0e046baa64d1aa1a6af97e2d19bb466cc1ff5)

1 files changed, 44 insertions, 1 deletions

diff --git a/jstests/core/elemmatch_or_pushdown.js b/jstests/core/elemmatch_or_pushdown.js
index f1a1dacd7ad..b33afcc23b8 100644
--- a/jstests/core/elemmatch_or_pushdown.js
+++ b/jstests/core/elemmatch_or_pushdown.js
@@ -1,5 +1,6 @@
 /**
- * Tests that an $elemMatch-$or query is evaluated correctly. Designed to reproduce SERVER-33005.
+ * Tests that an $elemMatch-$or query is evaluated correctly. Designed to reproduce SERVER-33005 and
+ * SERVER-38164.
  */
 (function() {
     "use strict";
@@ -38,4 +39,46 @@
                   .sort({_id: 1})
                   .toArray(),
               [{_id: 0, a: 5, b: [{c: [{f: 8}], d: 6}]}, {_id: 4, a: 5, b: [{c: [{f: 8}], e: 7}]}]);
+
+    // Test that $not predicates in $elemMatch can be pushed into an $or sibling of the $elemMatch.
+    coll.drop();
+    assert.writeOK(coll.insert({_id: 0, arr: [{a: 0, b: 2}], c: 4, d: 5}));
+    assert.writeOK(coll.insert({_id: 1, arr: [{a: 1, b: 2}], c: 4, d: 5}));
+    assert.writeOK(coll.insert({_id: 2, arr: [{a: 0, b: 3}], c: 4, d: 5}));
+    assert.writeOK(coll.insert({_id: 3, arr: [{a: 1, b: 3}], c: 4, d: 5}));
+    assert.writeOK(coll.insert({_id: 4, arr: [{a: 0, b: 2}], c: 6, d: 7}));
+    assert.writeOK(coll.insert({_id: 5, arr: [{a: 1, b: 2}], c: 6, d: 7}));
+    assert.writeOK(coll.insert({_id: 6, arr: [{a: 0, b: 3}], c: 6, d: 7}));
+    assert.writeOK(coll.insert({_id: 7, arr: [{a: 1, b: 3}], c: 6, d: 7}));
+
+    const keyPattern = {"arr.a": 1, "arr.b": 1, c: 1, d: 1};
+    assert.commandWorked(coll.createIndex(keyPattern));
+
+    const elemMatchOr = {
+        arr: {$elemMatch: {a: {$ne: 1}, $or: [{b: 2}, {b: 3}]}},
+        $or: [
+            {c: 4, d: 5},
+            {c: 6, d: 7},
+        ],
+    };
+
+    // Confirm that we get the same results using the index and a COLLSCAN.
+    for (let hint of[keyPattern, {$natural: 1}]) {
+        assert.eq(coll.find(elemMatchOr, {_id: 1}).sort({_id: 1}).hint(hint).toArray(),
+                  [{_id: 0}, {_id: 2}, {_id: 4}, {_id: 6}]);
+
+        assert.eq(
+            coll.aggregate(
+                    [
+                      {
+                        $match:
+                            {arr: {$elemMatch: {a: {$ne: 1}}}, $or: [{c: 4, d: 5}, {c: 6, d: 7}]}
+                      },
+                      {$project: {_id: 1}},
+                      {$sort: {_id: 1}}
+                    ],
+                    {hint: hint})
+                .toArray(),
+            [{_id: 0}, {_id: 2}, {_id: 4}, {_id: 6}]);
+    }
 }());