incubator-cassandra-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From aaron morton <aa...@thelastpickle.com>
Subject Re: Counters != Counts
Date Tue, 20 Dec 2011 18:58:04 GMT
Yes you can do a rolling restart. For more info on the counters architecture see the presentation
here 
http://www.datastax.com/events/cassandrasf2011/presentations

Cheers

-----------------
Aaron Morton
Freelance Developer
@aaronmorton
http://www.thelastpickle.com

On 20/12/2011, at 10:10 PM, Alain RODRIGUEZ wrote:

> By the way, I wonder if a rolling restart is still possible when I am using counters
? Don't we lose the SPOF too, considering that counters are wrong every time we retry to write
them with the client ?
> 
> 
> 2011/12/16 Alain RODRIGUEZ <arodrime@gmail.com>
> Can we have a hope that counters will be replayed as safely as a classical data someday
? Do someone still work on jiras like issues.apache.org/jira/browse/CASSANDRA-2495 ? I thought
that replaying a write from the client didn't lead to over-counts contrary to the internal
cassandra replay from commitlog.
> 
> I just made a new connection pool with retries / 2 and timeouts * 4. I hope it will improve
the accuracy of my counters.
> 
> Anyways, thank you for answering that fast.
> 
> Alain 
> 
> 2011/12/16 Tyler Hobbs <tyler@datastax.com>
> Probably quite a few of them are coming from automatic retries by phpcassa.  When working
with counters, I recommend minimizing retries and/or increasing timeouts.  Usually this means
you want to use a separate connection pool with different settings just for counters.
> 
> By the way, this advice applies to other clients as well.
> 
> 
> On Wed, Dec 14, 2011 at 10:29 AM, Alain RODRIGUEZ <arodrime@gmail.com> wrote:
> Hi everybody.
> 
> I'm using a lot of counters to make statistics on a 4 nodes cluster (ec2 m1.small) with
phpcassa (cassandra v1.0.2).
> 
> I store some events and increment counters at the same time.
> 
> Counters give me over-counts compared with the count of every corresponding events.
> 
> I sure that my non-counters counts are good.
> 
> I'm not sure why these over-counts happen, but I heard that recovering from commitlogs
can produce this.
> I have some timeouts on phpcassa which are written in my apache logs while a compaction
is running. However I am always able to write at Quorum, so I guess I shouldn't have to recover
from cassandra commitlogs. 
> 
> Where can these over-counts come from ?
> 
> Alain
>  
> 
> 
> 
> -- 
> Tyler Hobbs
> DataStax
> 
> 
> 


Mime
View raw message