title: PouchDB: warning: "no matching index found, create an index to optimize query time"
body: <p>I'm using pouchdb module and I have a warning when I search database. Warning message is like this. 
  warning: "no matching index found, create an index to optimize query time"</p>
  
  <p>Why do I have such warning? If someone knows a reason and solution could you tell me it?</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-js lang-js prettyprint-override"><code>var querySentenceDoc = {
      _id: '_design/query_sentence',
      views: {
          by_query_id: {
              map: function (doc, ctx) {
                  ctx.emit(doc.query_id, doc.sentnece_id);
              }.toString()
          }
      }
  };
  
  _this.query_sentence.put(querySentenceDoc).then(function () {
      _this.query_sentence.query('query_sentence/by_query_id', { stale: 'update_after' }).then(function () {
          if (proceedCb) {
              proceedCb();
          }
          return;
      });
  }).catch(function (err) {
      console.log('Sentences views maybe a 409, because it already exists?', err);
  });
  
  
  
  
  showSentenceIds: function (ids) {
      var param = { keys: ids, limit: 15, include_docs: true};
      return this.query_sentence.query('query_sentence/by_query_id', param);
  },
  
  models.showSentenceIds(ids).then(function (_s_ids) {
      sentenceIds = _s_ids;
      callback(null, 0);
  });</code></pre>
  </div>
  </div>
  </p>
  
  <h2>Heading</h2>