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Posted to user@cassandra.apache.org by DE VITO Dominique <do...@thalesgroup.com> on 2012/04/23 10:19:58 UTC

question about updates internal work in case of cache

Hi,

Let's suppose a column (name+value) is cached in memory, with timestamp T.

1) An update, for this column, arrives with exactly the *same* timestamp, and the *same* value.
Is the commitlog updated ?

2) An update, for this column, arrives with a timestamp < T.
Is the commitlog updated ?

Thanks for your help.

Regards,
Dominique

Re: question about updates internal work in case of cache

Posted by Sylvain Lebresne <sy...@datastax.com>.

On Mon, Apr 23, 2012 at 10:19 AM, DE VITO Dominique
<do...@thalesgroup.com> wrote:
> Hi,
>
>
>
> Let's suppose a column (name+value) is cached in memory, with timestamp T.
>
>
>
> 1) An update, for this column, arrives with exactly the *same* timestamp,
> and the *same* value.
>
> Is the commitlog updated ?
>
>
>
> 2) An update, for this column, arrives with a timestamp < T.
>
> Is the commitlog updated ?
>

Yes to both, the commit log is always updated. In fact, the commit log
insertion is done in parallel and independently with in-memory updates
(which include caches updates).

--
Sylvain

>
>
> Thanks for your help.
>
>
>
> Regards,
>
> Dominique
>
>