To provide crossdatabase tools for manipulating all major databases without having to worry about each vendors specific implementation.
提供跨数据库的工具，处理所有主流数据库，而不必担心每个开发商特定的实现。
2
Partitioning across multiple databases wouldn’t be a big deal if it were not for the fact that cross-database queries are not supported, forcing any unions or joins to be done in memory.