public function getSchemaCollection()
    {
        if ($this->_schemaCollection !== null) {
            return $this->_schemaCollection;
        }

        if (!empty($this->_config['cacheMetadata'])) {
            return $this->_schemaCollection = new CachedCollection($this, $this->_config['cacheMetadata']);
        }

        return $this->_schemaCollection = new SchemaCollection($this);
    }