1 files changed, 107 insertions, 0 deletions
diff --git a/jstests/sharding/lookup_change_stream_post_image_compound_shard_key.js b/jstests/sharding/lookup_change_stream_post_image_compound_shard_key.js
new file mode 100644
index 00000000000..022d5dd6172
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+++ b/jstests/sharding/lookup_change_stream_post_image_compound_shard_key.js
@@ -0,0 +1,107 @@
+// Tests the behavior of looking up the post image for change streams on collections which are
+// sharded with a compound shard key.
+(function() {
+    "use strict";
+
+    // For supportsMajorityReadConcern().
+    load("jstests/multiVersion/libs/causal_consistency_helpers.js");
+
+    if (!supportsMajorityReadConcern()) {
+        jsTestLog("Skipping test since storage engine doesn't support majority read concern.");
+        return;
+    }
+
+    const st = new ShardingTest({
+        shards: 2,
+        rs: {
+            nodes: 1,
+            enableMajorityReadConcern: '',
+            // Use a higher frequency for periodic noops to speed up the test.
+            setParameter: {writePeriodicNoops: true, periodicNoopIntervalSecs: 1}
+        }
+    });
+
+    const mongosDB = st.s0.getDB(jsTestName());
+    const mongosColl = mongosDB[jsTestName()];
+
+    assert.commandWorked(mongosDB.dropDatabase());
+
+    // Enable sharding on the test DB and ensure its primary is shard0000.
+    assert.commandWorked(mongosDB.adminCommand({enableSharding: mongosDB.getName()}));
+    st.ensurePrimaryShard(mongosDB.getName(), st.rs0.getURL());
+
+    // Shard the test collection with a compound shard key: a, b, c. Then split it into two chunks,
+    // and put one chunk on each shard.
+    assert.commandWorked(mongosDB.adminCommand(
+        {shardCollection: mongosColl.getFullName(), key: {a: 1, b: 1, c: 1}}));
+
+    // Split the collection into 2 chunks:
+    // [{a: MinKey, b: MinKey, c: MinKey}, {a: 1,      b: MinKey, c: MinKey})
+    // and
+    // [{a: 1,      b: MinKey, c: MinKey}, {a: MaxKey, b: MaxKey, c: MaxKey}).
+    assert.commandWorked(mongosDB.adminCommand(
+        {split: mongosColl.getFullName(), middle: {a: 1, b: MinKey, c: MinKey}}));
+
+    // Move the upper chunk to shard 1.
+    assert.commandWorked(mongosDB.adminCommand({
+        moveChunk: mongosColl.getFullName(),
+        find: {a: 1, b: MinKey, c: MinKey},
+        to: st.rs1.getURL()
+    }));
+
+    const changeStream = mongosColl.aggregate([{$changeStream: {fullDocument: "updateLookup"}}]);
+
+    const nDocs = 6;
+    const bValues = ["one", "two", "three", "four", "five", "six"];
+
+    // This shard key function results in 1/3rd of documents on shard0 and 2/3rds on shard1.
+    function shardKeyFromId(id) {
+        return {a: id % 3, b: bValues[id], c: id % 2};
+    }
+
+    // Do some writes.
+    for (let id = 0; id < nDocs; ++id) {
+        const documentKey = Object.merge({_id: id}, shardKeyFromId(id));
+        assert.writeOK(mongosColl.insert(documentKey));
+        assert.writeOK(mongosColl.update(documentKey, {$set: {updatedCount: 1}}));
+    }
+
+    for (let id = 0; id < nDocs; ++id) {
+        assert.soon(() => changeStream.hasNext());
+        let next = changeStream.next();
+        assert.eq(next.operationType, "insert");
+        assert.eq(next.documentKey, {_id: id});
+
+        assert.soon(() => changeStream.hasNext());
+        next = changeStream.next();
+        assert.eq(next.operationType, "update");
+        assert.eq(next.documentKey, Object.merge(shardKeyFromId(id), {_id: id}));
+        assert.docEq(next.fullDocument,
+                     Object.merge(shardKeyFromId(id), {_id: id, updatedCount: 1}));
+    }
+
+    // Test that the change stream can still see the updated post image, even if a chunk is
+    // migrated.
+    for (let id = 0; id < nDocs; ++id) {
+        const documentKey = Object.merge({_id: id}, shardKeyFromId(id));
+        assert.writeOK(mongosColl.update(documentKey, {$set: {updatedCount: 2}}));
+    }
+
+    // Move the upper chunk back to shard 0.
+    assert.commandWorked(mongosDB.adminCommand({
+        moveChunk: mongosColl.getFullName(),
+        find: {a: 1, b: MinKey, c: MinKey},
+        to: st.rs0.getURL()
+    }));
+
+    for (let id = 0; id < nDocs; ++id) {
+        assert.soon(() => changeStream.hasNext());
+        let next = changeStream.next();
+        assert.eq(next.operationType, "update");
+        assert.eq(next.documentKey, Object.merge(shardKeyFromId(id), {_id: id}));
+        assert.docEq(next.fullDocument,
+                     Object.merge(shardKeyFromId(id), {_id: id, updatedCount: 2}));
+    }
+
+    st.stop();
+})();