fixed issue #11275

jsteemann · jsteemann · commit b303e3302c83 · 2020-03-18T14:19:36.000+01:00
diff --git a/CHANGELOG b/CHANGELOG
@@ -53,6 +53,8 @@ devel
 * Supervision to clean up zombie servers after 24h, if no
   responsibility for shards.
 
+* Fixed issue #11275: indexes backward compatibility broken in 3.5+.
+
 * Fix SORT RAND() LIMIT 1 optimization for RocksDB when only a projection of the
   attributes was used. When a projection was used and that projection was
   covered by an index (e.g. `_key` via the primary index), then the access
diff --git a/arangod/RocksDBEngine/RocksDBVPackIndex.cpp b/arangod/RocksDBEngine/RocksDBVPackIndex.cpp
@@ -750,13 +750,16 @@ namespace {
   bool attributesEqual(VPackSlice first, VPackSlice second,
                        std::vector<arangodb::basics::AttributeName>::const_iterator begin,
                        std::vector<arangodb::basics::AttributeName>::const_iterator end) {
+    TRI_ASSERT(first.isObject());
+    TRI_ASSERT(second.isObject());
+
     for (; begin != end; ++begin) {
       // fetch subattribute
       first = first.get(begin->name);
-      second = second.get(begin->name);
       if (first.isExternal()) {
         first = first.resolveExternal();
       }
+      second = second.get(begin->name);
       if (second.isExternal()) {
         second = second.resolveExternal();
       }
@@ -784,6 +787,17 @@ namespace {
       if (notF1 || notF2) { // one of the paths was not found
         break;
       }
+   
+      // check if, after fetching the subattribute, we are point to a non-object.
+      // e.g. if the index is on field ["a.b"], the first iteration of this loop
+      // will look for subattribute "a" in the original document. this will always
+      // work. however, when looking for "b", we have to make sure that "a" was
+      // an object. otherwise we must not call Slice::get() on it. In case one of
+      // the subattributes we found so far is not an object, we fall back to the
+      // regular comparison
+      if (!first.isObject() || !second.isObject()) {
+        break;
+      }
     }
 
     return basics::VelocyPackHelper::equal(first, second, true);
