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From Hontvári József Levente <>
Subject is it possible to read obsolete data after write?
Date Mon, 20 Feb 2012 12:32:58 GMT
I noticed a strange phenomenon with Cassandra, and I would like to know 
if this is something completely impossible, or not.

As you can see in the log extract below, as new versions of a row is 
written out, the reads returns obsolete data after a while (they read 
version 78 when 79 and even 80 is already written out). There is only a 
single Cassandra node in the cluster, the client is on the same local 
network, there are about 10 rows written and read per seconds. I would 
think that in this test environment I should not see any obsolete data 
at all. But actually I have thousands of log entries after a few hours 
of test, which say that the row which was read does not match the latest 
data which was written.

I checked in detail the history of another node, and it seems that 
eventually I receive an up-to-date row, but it took once 10 and once 15 
minutes in this specific case.

(FYI: I am just started to evaluate Cassandra, without any significant 

            09:43:46Z Persisting version=77
GOOD       09:45:20Z Loading version=77
            09:45:21Z Persisting version=78
GOOD       09:46:23Z Loading version=78
            09:46:23Z Persisting version=79
WRONG!     09:47:12Z Loading version=78
            09:47:12Z Persisting version=80
WRONG!!    09:49:20Z Loading version=78
            09:49:20Z Persisting version=81

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