incubator-cassandra-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Jonathan Ellis <jbel...@gmail.com>
Subject Re: Occasionally getting old data back with ConsistencyLevel.ALL
Date Thu, 18 Aug 2011 15:31:35 GMT
There are a lot of people on 0.7 for whom CL is working as advertised.
 Not saying it's impossible that there's a bug, but the odds are
against it.

Is it possible for instance that sometimes your cron job takes longer
than five minutes?

On Thu, Aug 18, 2011 at 9:49 AM, Kyle Gibson
<kyle.gibson@frozenonline.com> wrote:
> I am running cassandra 0.7.8. pycassa 1.1.0
>
> Nodes=7, RF=3
>
> This problem started a few months ago and only occurs sporadically.
>
> I receive notifications from paypal's IPN. The IPN data is saved into
> a column family. I add another column for "processed" which is set to
> 0.
>
> Every 5 minutes, a cron script runs and pulls down IPN events that
> haven't been processed. It does some work, and then writes back
> processed to 1.
>
> Usually this worked, but then (when exactly I don't recall),
> occasionally, it started having a problem. Processed wasn't been set
> to 1. So, IPN events would be processed twice.
>
> I tried a few things to fix this. Repair, compact, restarting the
> cluster, upgrading. I even did a complete rebuild of the cluster,
> wiping the data directory and starting fresh on 0.7.8.
>
> I then ditched the "processed" column and decide to use two column
> families. IPNs are put into column family A, and after being
> processed, it is inserted into column family B and deleted from A.
>
> The problem still persisted. At this point I was using CL.QUORUM. So,
> I started using CL.ALL.
>
> And the problem still persists. Having IPN events processed twice
> causes a fair bit of problems, so this is something I really need to
> get resolved.
>
> Thanks,
>
> Kyle
>



-- 
Jonathan Ellis
Project Chair, Apache Cassandra
co-founder of DataStax, the source for professional Cassandra support
http://www.datastax.com

Mime
View raw message