而在关系语言中，这种查询需要进行也许跨越了多个数据表和系统目录表的联接。
In a relational language, such a query would require a join that might span several data tables and system catalog tables.
如果您试图创建跨越文件系统或用于目录的硬链接，您会得到一个错误。
You will get an error if you attempt to create hard links that cross file systems or that are for directories.
时常安装目录即是音量，能跨越多个分区。
Mounted directories are often known as volumes, which can span multiple partitions.
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