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From Roshan Dawrani <roshandawr...@gmail.com>
Subject Re: Basic question on a write operation immediately followed by a read
Date Tue, 25 Jan 2011 04:15:58 GMT
2011/1/25 Patricio Echag├╝e <patricioe@gmail.com>

> Roshan, for specifics have a look at
> http://wiki.apache.org/cassandra/ArchitectureOverview specially where it
> says "Write path".


I went through the "Write path" section and have a small follow-up question,
please - again assuming a 1-node setup for now.

How much of a "write" is done before a client mutation call is returned?

a) Does it only write to the commit log and come back? And even updates to
memtables happen in the background after that?

b) Does it come back after writing to the commit log and updates to
memtables both have happened?

I am asking because if it is a), then is it is possible that a read
operation happens after commit log has been written to, but memtables are
not updated yet? (I assume reads are off memtables and not take into account
what is in commit logs)

Basic question again is whether in "any" scenario, a read might miss a write
that has just happened.

Thanks.

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