Able to use indexes for matches

lib/datastore.js

@@ -178,9 +178,10 @@ Datastore.prototype.updateIndexes = function (oldDoc, newDoc) {
 
 /**
  * Return the list of candidates for a given query
- * Very crude implementation for now, we return the candidates given by the first usable index if any
- * Also indexes can only be used for direct matches (no $lt, $gt or array yet)
- * This still gives a huge performance boost to finds (800x on a collection with 10k documents)
+ * Crude implementation for now, we return the candidates given by the first usable index if any
+ * We try the following query types, in this order: basic match, $in match, comparison match
+ * One way to make it better would be to enable the use of multiple indexes if the first usable index
+ * returns too much data. I may do it in the future.
  */
 Datastore.prototype.getCandidates = function (query) {
   var indexNames = Object.keys(this.indexes)
@@ -188,21 +189,32 @@ Datastore.prototype.getCandidates = function (query) {
 
   if (indexNames.length <= 1) { return this.getAllData(); }   // No index defined (except _id), no specific candidate
 
-  // Usable query keys are the ones corresponding to a basic query (no use of $operators or arrays)
+  // For a basic match
   usableQueryKeys = [];
   Object.keys(query).forEach(function (k) {
     if (typeof query[k] === 'string' || typeof query[k] === 'number' || typeof query[k] === 'boolean' || util.isDate(query[k]) || query[k] === null) {
       usableQueryKeys.push(k);
     }
   });
-
   usableQueryKeys = _.intersection(usableQueryKeys, indexNames);
-
   if (usableQueryKeys.length > 0) {
     return this.indexes[usableQueryKeys[0]].getMatching(query[usableQueryKeys[0]]);
-  } else {
-    return this.getAllData();
   }
+
+  // For a $in match
+  usableQueryKeys = [];
+  Object.keys(query).forEach(function (k) {
+    if (query[k].hasOwnProperty('$in')) {
+      usableQueryKeys.push(k);
+    }
+  });
+  usableQueryKeys = _.intersection(usableQueryKeys, indexNames);
+  if (usableQueryKeys.length > 0) {
+    return this.indexes[usableQueryKeys[0]].getMatching(query[usableQueryKeys[0]].$in);
+  }
+
+  // By default, return all the DB data
+    return this.getAllData();
 };
 
 

lib/executor.js

@@ -1,7 +1,5 @@
 /**
  * Responsible for sequentially executing actions on the database
- * async.queue is actually slowing down the code (10% hit on inserts, 3% on updates/removes)
- * That's not critical for the intended uses but I may reimplement this in the future
  */
 
 var async = require('async')
@@ -46,6 +44,5 @@ Executor.prototype.push = function () {
 
 
 
-
 // Interface
 module.exports = Executor;

lib/indexes.js

@@ -182,15 +182,31 @@ Index.prototype.revertUpdate = function (oldDoc, newDoc) {
 };
 
 
+// Append all elements in toAppend to array
+function append (array, toAppend) {
+  var i;
+
+  for (i = 0; i < toAppend.length; i += 1) {
+    array.push(toAppend[i]);
+  }
+}
+
+
 /**
- * Get all documents in index that match the query on fieldName
- * For now only works with field equality (i.e. can't use the index for $lt query for example)
- * And doesn't return non indexed docs
+ * Get all documents in index whose key match value (if it is a Thing) or one of the elements of value (if it is an array of Things)
  * @param {Thing} value Value to match the key against
  * @return {Array of documents}
  */
 Index.prototype.getMatching = function (value) {
-  return this.tree.search(value);
+  var res, self = this;
+
+  if (!util.isArray(value)) {
+    return this.tree.search(value);
+  } else {
+    res = [];
+    value.forEach(function (v) { append(res, self.getMatching(v)); });
+    return res;
+  }
 };
 
 

package.json

@@ -22,7 +22,7 @@
   "dependencies": {
     "async": "~0.2.8",
     "underscore": "~1.4.4",
-    "binary-search-tree": "0.2.2"
+    "binary-search-tree": "0.2.3"
   },
   "devDependencies": {
     "chai": "1.0.x",

test/db.test.js

@@ -449,6 +449,84 @@ describe('Database', function () {
   });   // ==== End of 'Insert' ==== //
 
 
+  describe('#getCandidates', function () {
+
+    it('Can use an index to get docs with a basic match', function (done) {
+      d.ensureIndex({ fieldName: 'tf' }, function (err) {
+        d.insert({ tf: 4 }, function (err, _doc1) {
+          d.insert({ tf: 6 }, function () {
+            d.insert({ tf: 4, an: 'other' }, function (err, _doc2) {
+              d.insert({ tf: 9 }, function () {
+                var data = d.getCandidates({ r: 6, tf: 4 })
+                  , doc1 = _.find(data, function (d) { return d._id === _doc1._id; })
+                  , doc2 = _.find(data, function (d) { return d._id === _doc2._id; })
+                  ;
+
+                data.length.should.equal(2);
+                assert.deepEqual(doc1, { _id: doc1._id, tf: 4 });
+                assert.deepEqual(doc2, { _id: doc2._id, tf: 4, an: 'other' });
+
+                done();
+              });
+            });
+          });
+        });
+      });
+    });
+
+    it('Can use an index to get docs with a $in match', function (done) {
+      d.ensureIndex({ fieldName: 'tf' }, function (err) {
+        d.insert({ tf: 4 }, function (err) {
+          d.insert({ tf: 6 }, function (err, _doc1) {
+            d.insert({ tf: 4, an: 'other' }, function (err) {
+              d.insert({ tf: 9 }, function (err, _doc2) {
+                var data = d.getCandidates({ r: 6, tf: { $in: [6, 9, 5] } })
+                  , doc1 = _.find(data, function (d) { return d._id === _doc1._id; })
+                  , doc2 = _.find(data, function (d) { return d._id === _doc2._id; })
+                  ;
+
+                data.length.should.equal(2);
+                assert.deepEqual(doc1, { _id: doc1._id, tf: 6 });
+                assert.deepEqual(doc2, { _id: doc2._id, tf: 9 });
+
+                done();
+              });
+            });
+          });
+        });
+      });
+    });
+
+    it('If no index can be used, return the whole database', function (done) {
+      d.ensureIndex({ fieldName: 'tf' }, function (err) {
+        d.insert({ tf: 4 }, function (err, _doc1) {
+          d.insert({ tf: 6 }, function (err, _doc2) {
+            d.insert({ tf: 4, an: 'other' }, function (err, _doc3) {
+              d.insert({ tf: 9 }, function (err, _doc4) {
+                var data = d.getCandidates({ r: 6, notf: { $in: [6, 9, 5] } })
+                  , doc1 = _.find(data, function (d) { return d._id === _doc1._id; })
+                  , doc2 = _.find(data, function (d) { return d._id === _doc2._id; })
+                  , doc3 = _.find(data, function (d) { return d._id === _doc3._id; })
+                  , doc4 = _.find(data, function (d) { return d._id === _doc4._id; })
+                  ;
+
+                data.length.should.equal(4);
+                assert.deepEqual(doc1, { _id: doc1._id, tf: 4 });
+                assert.deepEqual(doc2, { _id: doc2._id, tf: 6 });
+                assert.deepEqual(doc3, { _id: doc3._id, tf: 4, an: 'other' });
+                assert.deepEqual(doc4, { _id: doc4._id, tf: 9 });
+
+                done();
+              });
+            });
+          });
+        });
+      });
+    });
+
+  });   // ==== End of '#getCandidates' ==== //
+
+
   describe('Find', function () {
 
     it('Can find all documents if an empty query is used', function (done) {

test/indexes.test.js

@@ -526,6 +526,28 @@ describe('Indexes', function () {
       assert.deepEqual(idx.getMatching(undefined), []);
     });
 
+    it('Can get all documents whose key is in an array of keys', function () {
+      var idx = new Index({ fieldName: 'tf' })
+        , doc1 = { a: 5, tf: 'hello' }
+        , doc2 = { a: 2, tf: 'bloup' }
+        , doc3 = { a: 8, tf: 'world' }
+        , doc4 = { a: 7, tf: 'yes' }
+        , doc5 = { a: 7, tf: 'yes' }
+        ;
+
+      idx.insert(doc1);
+      idx.insert(doc2);
+      idx.insert(doc3);
+      idx.insert(doc4);
+      idx.insert(doc5);
+
+      assert.deepEqual(idx.getMatching([]), []);
+      assert.deepEqual(idx.getMatching(['bloup']), [doc2]);
+      assert.deepEqual(idx.getMatching(['bloup', 'yes']), [doc2, doc4, doc5]);
+      assert.deepEqual(idx.getMatching(['hello', 'no']), [doc1]);
+      assert.deepEqual(idx.getMatching(['nope', 'no']), []);
+    });
+
   });   // ==== End of 'Get matching documents' ==== //