Cross joins(交叉连接) 一个cross join 相当于对两个表执行了一次完全的笛卡尔乘积。也就是说,它会用其中一个表里的每一行来匹配另 外一个表的每一行。
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...rr Sean Chai Sean Chai Eva Corets Eva Corets Mary O’Melia Mary O’Melia 1 Adam Barr 交叉联接(Cross Joins) 得到所连接表的所有组合(笛卡尔积) 交叉联接 得到所连接表的所有组合(笛卡儿积 ) 其联接结果会产生一些没有意义的记录。
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Cross-Product Joins 交叉连接
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.
由于跨数据库查询不被支持,所以跨多个数据库的分区是个棘手的问题,任何union或join操作都需要在内存中完成。
SimpleDB also doesn't support the notion of cross-domain joins, so you can't query for items in multiple domains.
SimpleDB 也不支持跨域联接的概念,因此您不能查询多个域中的项目。
After China joins WTO, the enterprises in his west hill face the challenges from the enterprises at the developed area and the cross nation ones as well.
我国加入WTO以后,西部企业面临着发达地区企业和跨国企业的双重挑战。
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