该层将一段源id映射到物理数据库，对于同一个物理地址的表，通过建立树来处理。

A forwarding layer maps ranges of source IDs to physical databases, and replication is handled by building a tree of such tables under the same forwarding address.

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操作系统通过一个内部表将处理器地址空间中的内存段映射到内存页，该表定义哪些内存段由哪些处理器所拥有，等等。

Operating systems map memory segments in a processes' address space to memory pages through an internal table which defines what memory segments are owned by what processes, and so on.

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由于每个页都要由每个进程映射，必须创建页表条目来将虚拟地址映射到物理地址。

For every page mapped by each process, page-table entries must also be created to map the virtual address to the physical address.

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