cassandra-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Milind Parikh <>
Subject Re: Consistency model
Date Sun, 17 Apr 2011 15:24:24 GMT
The issue is regarding whether you will see A or B; with any guarantee of
either. The discussion implies no; until the QW is complete.

sent from my android...please pardon occasional typos as I respond @ the
speed of thought

On Apr 17, 2011 7:48 AM, "William Oberman" <> wrote:

I'm pretty new to all of this, and I'm in the process of building my mental
model of Cassandra, but I'm still feeling better about this thread. The way
I figure it:
1. I'm trying to mutate the state of a key's column from A to B from a
thread somewhere (quorum)
2. I'm trying to read the state of a key from a thread somewhere else

If #1 succeeds I'm guaranteed to see B. If #1 fails (with an exception) I'll
see either A or B. I think I was concerned about that, and wanted to see A
in #2 until success in #1.  But, I wanted to get to state B, and if #1
retries until guaranteed success, do I care if I set B earlier than I
expected?  I'm thinking no.

I guess in terms of distributed algorithms/reasoning about systems, I'm
feeling ok with this level of guarantee (again, given the failed write tells
the client code of the undefined state).

On Apr 17, 2011, at 10:10 AM, James Cipar <> wrote:

> I'm pretty new to Cassandra, ...

View raw message