arangodb · KVS85 · Sep 22, 2021 · Aug 26, 2021 · Aug 26, 2021 · Aug 26, 2021
diff --git a/CHANGELOG b/CHANGELOG
@@ -1,6 +1,8 @@
 v3.8.2 (XXXX-XX-XX)
 -------------------
 
+* Fixed a bug for array indexes on update of documents (BTS-548).
+
 * Fixed BTS-562: reduce-extraction-to-projection optimization returns null for
   one attribute if nested attributes are named the same.
 
@@ -14,8 +16,8 @@ v3.8.2 (XXXX-XX-XX)
   trying to modify the list of collections (very unlikely and never observed
   until now).
 
-* Fix active failover, so that the new host actually has working
-  foxx services. (BTS-558)
+* Fix active failover, so that the new host actually has working foxx services
+  (BTS-558).
 
 * Fixed issue #14720: Bulk import ignores onDuplicate in 3.8.0.
   The "onDuplicate" attribute was ignored by the `/_api/import` REST API when

diff --git a/arangod/RocksDBEngine/RocksDBVPackIndex.cpp b/arangod/RocksDBEngine/RocksDBVPackIndex.cpp
@@ -989,6 +989,15 @@ namespace {
 
       if (begin->shouldExpand &&
           first.isArray() && second.isArray()) {
+        if (first.length() != second.length()) {
+          // Nonequal length, so there is a difference!
+          // We have to play this carefully here. It is possible that the
+          // set of values found is the same, but we must err on the side
+          // of caution in this case and use the slow path. Note in
+          // particular that the following code returns `true`, if one
+          // of the arrays is empty, which is not correct!
+          return false;
+        }
         auto next = begin + 1;
         VPackArrayIterator it1(first), it2(second);
         while (it1.valid() && it2.valid()) {

diff --git a/tests/js/server/shell/shell-array-index-noncluster.js b/tests/js/server/shell/shell-array-index-noncluster.js
@@ -275,7 +275,75 @@ function arraySkiplistIndexSuite () {
       catch (err) {
         assertEqual(errors.ERROR_ARANGO_UNIQUE_CONSTRAINT_VIOLATED.code, err.errorNum);
       }
-    }
+    },
+
+////////////////////////////////////////////////////////////////////////////////
+/// @brief test: Test update of an array index where entries are removed:
+////////////////////////////////////////////////////////////////////////////////
+
+    testPersistentArrayIndexUpdates : function () {
+      collection.ensureIndex({type:"persistent", fields: ["a[*].b"], unique: true});
+
+      let meta = collection.insert({a: [{b:"xyz"}]});
+
+      try {
+        collection.insert({a: [{b:"xyz"}]});
+        fail();
+      }
+      catch (err) {
+        assertEqual(errors.ERROR_ARANGO_UNIQUE_CONSTRAINT_VIOLATED.code, err.errorNum);
+      }
+
+      collection.update(meta._key, {a: []});
+
+      let meta2 = collection.insert({a: [{b:"xyz"}]});  // must work again
+
+      try {
+        collection.insert({a: [{b:"xyz"}]});
+        fail();
+      }
+      catch (err) {
+        assertEqual(errors.ERROR_ARANGO_UNIQUE_CONSTRAINT_VIOLATED.code, err.errorNum);
+      }
+
+      collection.replace(meta2._key, {a: []});
+
+      collection.insert({a: [{b:"xyz"}]});  // must work again
+    },
+
+////////////////////////////////////////////////////////////////////////////////
+/// @brief test: Test update of an array index where entries are changed:
+////////////////////////////////////////////////////////////////////////////////
+
+    testPersistentArrayIndexUpdates2 : function () {
+      collection.ensureIndex({type:"persistent", fields: ["a[*].b"], unique: true});
+
+      let meta = collection.insert({a: [{b:"xyz"}]});
+
+      try {
+        collection.insert({a: [{b:"xyz"}]});
+        fail();
+      }
+      catch (err) {
+        assertEqual(errors.ERROR_ARANGO_UNIQUE_CONSTRAINT_VIOLATED.code, err.errorNum);
+      }
+
+      collection.update(meta._key, {a: [{b:"123"}]});
+
+      let meta2 = collection.insert({a: [{b:"xyz"}]});  // must work again
+
+      try {
+        collection.insert({a: [{b:"xyz"}]});
+        fail();
+      }
+      catch (err) {
+        assertEqual(errors.ERROR_ARANGO_UNIQUE_CONSTRAINT_VIOLATED.code, err.errorNum);
+      }
+
+      collection.replace(meta2._key, {a: [{b:"456"}]});
+
+      collection.insert({a: [{b:"xyz"}]});  // must work again
+    },
 
   };
 }