1 files changed, 93 insertions, 0 deletions
diff --git a/jstests/core/timeseries/timeseries_lookup.js b/jstests/core/timeseries/timeseries_lookup.js
index 75a80a48177..d95bf137f5a 100644
--- a/jstests/core/timeseries/timeseries_lookup.js
+++ b/jstests/core/timeseries/timeseries_lookup.js
@@ -85,6 +85,99 @@ TimeseriesTest.run((insert) => {
             assert.eq({host: "host_" + i, matchedB: entryCountPerHost[i]}, results[i], results);
         }
 
+        // Equality Match With Let (uncorrelated)
+        // Make sure injected $sequentialDocumentCache (right after unpack bucket stage)
+        // in the inner pipeline is removed.
+        results = collA.aggregate([
+            {
+                $lookup: {
+                    from: collB.getName(),
+                    let: {"outer_hostname": "$tags.hostname"},
+                    pipeline: [
+                        // $match will be pushed before unpack bucket stage
+                        {$match: {$expr: {$eq: ["$$outer_hostname", hosts[0].tags.hostname]}}},
+                    ],
+                    as: "matchedB"
+                }
+            }, {
+                $project: {
+                    _id: 0,
+                    host: "$tags.hostname",
+                    matchedB: {
+                        $size: "$matchedB"
+                    }
+                }
+            },
+            {$sort: {host: 1}}
+        ]).toArray();
+        assert.eq(numHosts, results.length, results);
+        for (let i = 0; i < numHosts; i++) {
+            const matched = i === 0 ? numDocs : 0;
+            assert.eq({host: "host_" + i, matchedB: matched}, results[i], results);
+        }
+
+        // Equality Match With Let (uncorrelated)
+        // Make sure injected $sequentialDocumentCache in the inner pipeline is removed.
+        // $sequentialDocumentCache is not located right after unpack bucket stage.
+        results = collA.aggregate([
+                    {
+                        $lookup: {
+                            from: collB.getName(),
+                            let: {"outer_hostname": "$tags.hostname"},
+                            pipeline: [
+                                {$match: {$expr: {$eq: ["$$outer_hostname", hosts[0].tags.hostname]}}},
+                                {$set: {foo: {$const: 123}}},  // uncorrelated
+                            ],
+                            as: "matchedB"
+                        }
+                    }, {
+                        $project: {
+                            _id: 0,
+                            host: "$tags.hostname",
+                            matchedB: {
+                                $size: "$matchedB"
+                            }
+                        }
+                    },
+                    {$sort: {host: 1}}
+                ]).toArray();
+        assert.eq(numHosts, results.length, results);
+        for (let i = 0; i < numHosts; i++) {
+            const matched = i === 0 ? numDocs : 0;
+            assert.eq({host: "host_" + i, matchedB: matched}, results[i], results);
+        }
+
+        // Equality Match With Let (correlated, no $match re-order)
+        // Make sure injected $sequentialDocumentCache in the inner pipeline is removed.
+        // $sequentialDocumentCache is located at the very end of pipeline.
+        results = collA.aggregate([
+            {
+                $lookup: {
+                    from: collB.getName(),
+                    let: {"outer_hostname": "$tags.hostname"},
+                    pipeline: [
+                        {$match: {$expr: {$eq: ["$$outer_hostname", hosts[0].tags.hostname]}}},
+                        {$set: {foo: "$$outer_hostname"}},  // correlated
+                    ],
+                    as: "matchedB"
+                }
+            }, {
+                $project: {
+                    _id: 0,
+                    host: "$tags.hostname",
+                    matchedB: {
+                        $size: "$matchedB"
+                    }
+                }
+            },
+            {$sort: {host: 1}}
+        ]).toArray();
+        assert.eq(numHosts, results.length, results);
+        for (let i = 0; i < numHosts; i++) {
+            const matched = i === 0 ? numDocs : 0;
+            assert.eq({host: "host_" + i, matchedB: matched}, results[i], results);
+        }
+
         // Unequal joins
         results = collA.aggregate([
             {