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From Edmon Begoli <ebeg...@gmail.com>
Subject Robustness of MemTable
Date Mon, 30 Jul 2012 19:19:11 GMT
What is the redundancy/recovery mechanism of Write-Ahead Log and MemTable.

I am specifically asking about this statement and the parts about:

"When a write arrives at a TabletServer it is written to a Write-Ahead
Log and then inserted into a sorted data structure in memory called a
MemTable.
...
If a TabletServer fails, the Master detects it and automatically
reassigns the tablets assigned from the failed server to other
servers.
Any key-value pairs that were in memory at the time the TabletServer
are automatically reapplied from the Write-Ahead Log to prevent any
loss of data."

I.e. what happens if machine holding a MemTable crashes. Will
key-value pairs that we in memory have been replicated already?

Thank you,
Edmon

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