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From Jason Huang <jason.hu...@icare.com>
Subject HBase 'Real-Time' reads?
Date Wed, 12 Sep 2012 21:15:23 GMT
This might be a naive question but I am not able to find a good answer
from searching online.

The online guide mentioned that "Puts and Deletes are collected into
an in-memory structure called the MemStore. Before the MemStore is
update the changes are written to a Write Ahead Log (WAL) to enable
recovery in case a server crashes. When it reaches a certain size the
MemStore is flushed to disk into StoreFile."

So, if an application tried to query a certain piece of data that
hasn't been flushed to disk into StoreFile yet, where is HBase
designed to get that piece of data? Is it going to the Region servers
and tried to get the previous version of this data, or is it smart
enough to go to the MemStore or WAL to get the most recent version of
data?

thanks!

Jason

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