For years,RDBMS vendors have offered proprietary add-ons which gave users incremental capabilities but did not let them extend the database to understand the data formats,functions or complex queries of their own industries or even their own enterprises.

• 多年来，RDBMS公司提供专有的附加功能，让用户增加功能，但又不让他们扩展数据库以理解各自行业、甚至他们自己企业的多种数据格式、功能或复杂查询。