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From Alain RODRIGUEZ <arodr...@gmail.com>
Subject Re: Counters != Counts
Date Tue, 20 Dec 2011 09:10:27 GMT
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 <http://datastax.com/>
>>
>>
>

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