In progress

lib/datastore.js

@@ -489,10 +489,11 @@ Datastore.prototype.remove = function () {
   this.executor.push({ this: this, fn: this._remove, arguments: arguments });
 };
 
+
 /*
 var db = new Datastore({ inMemoryOnly: true })
 
-//db.ensureIndex({ fieldName: 'tag' });
+db.ensureIndex({ fieldName: 'tag' });
 
 db.insert({ tag: ['a', 'b', 'c'] }, function () {
   db.find({ tag: 'b' }, function (err, item) {

lib/indexes.js

@@ -14,6 +14,8 @@ function checkValueEquality (a, b) {
 
 /**
  * Create a new index
+ * All methods on an index guarantee that either the whole operation was successful and the index changed
+ * or the operation was unsuccessful and an error is thrown while the index is unchanged
  * @param {String} options.fieldName On which field should the index apply (can use dot notation to index on sub fields)
  * @param {Boolean} options.unique Optional, enforce a unique constraint (default: false)
  * @param {Boolean} options.sparse Optional, allow a sparse index (we can have documents for which fieldName is undefined) (default: false)

test/indexes.test.js

@@ -121,6 +121,19 @@ describe('Indexes', function () {
       assert.deepEqual(idx.tree.search('bloup'), []);
     });
 	
+	describe.only('Array fields', function () {
+	
+	  it('Inserts one entry per unique array element in the index', function () {
+		var obj = { arr: [], really: 'yeah' }
+		  , idx = new Index({ fieldName: 'tf' })
+		  ;
+		
+		idx.insert(obj);
+		
+	  });
+	
+	});   // ==== End of 'Array fields' ==== //
+
   });   // ==== End of 'Insertion' ==== //