why does write-around have inconsistency?

why does write-around have inconsistency?
data is never written into cache, so no inconsistency between cache and database.

Thanks,

Write around 虽然在写的路径上不会更新 Cache,但在读的路径上会更新 Cache。当 Cache 背后的数据再次被重新写了以后,因为是 Write around,所以不会通知 Cache 这次更新。再次读的时候就会出现读到 Cache 里的旧数据的问题。

Thanks, then why does read-though has best write, it is slower in read because cache has to fetch database in case of cache miss?

Sincerely,

Read through 本身跟写没关系。 Read-through + Write-back 是 Best Write 是因为写的时候只需要写 Cache,所以写是最快,读也不慢。