Don't load full query results in findOne()

History.md

@@ -1,6 +1,9 @@
 
 ## vNEXT
 
+* Calling `findOne()` on the server no longer loads the full query result
+  into memory.
+
 * Fix Spark memory leak.  #1157
 
 * Upgraded dependencies:

docs/client/api.html

@@ -655,7 +655,8 @@ disable this behavior, pass `{reactive: false}` as an option to
 
 {{> api_box findone}}
 
-Equivalent to `find(selector, options).fetch()[0]`.
+Equivalent to `find(selector, options).fetch()[0]` with
+`options.limit = 1`.
 
 {{> api_box insert}}
 

packages/mongo-livedata/mongo_driver.js

@@ -288,7 +288,8 @@ _Mongo.prototype.findOne = function (collection_name, selector, options) {
   if (arguments.length === 1)
     selector = {};
 
-  // XXX use limit=1 instead?
+  options = options || {};
+  options.limit = 1;
   return self.find(collection_name, selector, options).fetch()[0];
 };