perf: avoid adding all doc array subpaths when 1 path is modified

Author: vkarpov15

lib/document.js

@@ -2682,15 +2682,9 @@ function _getPathsToValidate(doc, pathsToValidate, pathsToSkip) {
       }
     }
 
-    // If underneath a document array, may need to re-validate the parent
-    // array re: gh-6818
-    if (_pathType.$parentSchemaDocArray && typeof _pathType.$parentSchemaDocArray.path === 'string') {
-      paths.add(_pathType.$parentSchemaDocArray.path);
-    }
-
     // Optimization: if primitive path with no validators, or array of primitives
     // with no validators, skip validating this path entirely.
-    if (!_pathType.caster && _pathType.validators.length === 0) {
+    if (!_pathType.caster && _pathType.validators.length === 0 && !_pathType.$parentSchemaDocArray) {
       paths.delete(path);
     } else if (_pathType.$isMongooseArray &&
       !_pathType.$isMongooseDocumentArray && // Skip document arrays...
@@ -2777,7 +2771,19 @@ function _getPathsToValidate(doc, pathsToValidate, pathsToSkip) {
 
   for (const path of paths) {
     const _pathType = doc.$__schema.path(path);
-    if (!_pathType || !_pathType.$isSchemaMap) {
+
+    if (!_pathType) {
+      continue;
+    }
+
+    // If underneath a document array, may need to re-validate the parent
+    // array re: gh-6818. Do this _after_ adding subpaths, because
+    // we don't want to add every array subpath.
+    if (_pathType.$parentSchemaDocArray && typeof _pathType.$parentSchemaDocArray.path === 'string') {
+      paths.add(_pathType.$parentSchemaDocArray.path);
+    }
+
+    if (!_pathType.$isSchemaMap) {
       continue;
     }