perf(model): make insertMany() lean option skip hydrating Mongoos…

…e docs

Fix #14372

lib/model.js

@@ -3430,6 +3430,13 @@ Model.$__insertMany = function(arr, options, callback) {
  const results = ordered ? null : new Array(arr.length);
  const toExecute = arr.map((doc, index) =>
  callback => {
+ // If option `lean` is set to true bypass validation and hydration
+ if (lean) {
+ // we have to execute callback at the nextTick to be compatible
+ // with parallelLimit, as `results` variable has TDZ issue if we
+ // execute the callback synchronously
+ return immediate(() => callback(null, doc));
+ }
  if (!(doc instanceof _this)) {
  try {
  doc = new _this(doc);
@@ -3440,13 +3447,6 @@ Model.$__insertMany = function(arr, options, callback) {
  if (options.session != null) {
  doc.$session(options.session);
  }
- // If option `lean` is set to true bypass validation
- if (lean) {
- // we have to execute callback at the nextTick to be compatible
- // with parallelLimit, as `results` variable has TDZ issue if we
- // execute the callback synchronously
- return immediate(() => callback(null, doc));
- }
  doc.$validate({ __noPromise: true }, function(error) {
  if (error) {
  // Option `ordered` signals that insert should be continued after reaching
@@ -3510,7 +3510,7 @@ Model.$__insertMany = function(arr, options, callback) {
  callback(null, []);
  return;
  }
- const docObjects = docAttributes.map(function(doc) {
+ const docObjects = lean ? docAttributes : docAttributes.map(function(doc) {
  if (doc.$__schema.options.versionKey) {
  doc[doc.$__schema.options.versionKey] = 0;
  }
@@ -3572,6 +3572,9 @@ Model.$__insertMany = function(arr, options, callback) {
  return !isErrored;
  }).
  map(function setIsNewForInsertedDoc(doc) {
+ if (lean) {
+ return doc;
+ }
  doc.$__reset();
  _setIsNew(doc, false);
  return doc;
@@ -3588,9 +3591,11 @@ Model.$__insertMany = function(arr, options, callback) {
  return;
  }
 
- for (const attribute of docAttributes) {
- attribute.$__reset();
- _setIsNew(attribute, false);
+ if (!lean) {
+ for (const attribute of docAttributes) {
+ attribute.$__reset();
+ _setIsNew(attribute, false);
+ }
  }
 
  if (rawResult) {