Pimcore\Cache\Backend\Mongodb::getTags PHP Method

    public function getTags()
    {
        $cmd['mapreduce'] = $this->_options['collection'];
        $cmd['map'] = 'function(){
                                this.t.forEach(
                                    function(z){
                                        emit( z , { count : 1 } );
                                    }
                                );
                            };';
        $cmd['reduce'] = 'function( key , values ){
                                var total = 0;
                                for ( var i=0; i<values.length; i++ )
                                    total += values[i].count;
                                return { count : total };
                            };';
        $cmd['out'] = ['replace' => 'getTagsCollection'];
        $res2 = $this->_db->command($cmd);
        $res3 = $this->_db->selectCollection('getTagsCollection')->find();
        $res = [];
        foreach ($res3 as $key => $val) {
            $res[] = $key;
        }
        $this->_db->dropCollection($res2['result']);
        return $res;
    }