cassandra-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Phil Stanhope <stanh...@gmail.com>
Subject Re: Not overwriting values
Date Tue, 21 Sep 2010 19:39:29 GMT
My experience is that timestamps have to be sequentially increasing for
writes to work. Soft/silent error if you do not follow this protocol.
Haven't tested against > 0.6.4 though.

On Tue, Sep 21, 2010 at 8:29 AM, Lucas Nodine <lucasnodine@gmail.com> wrote:

> Chris, I believe if the timestamp being written if the same or older it
> will not apply the write, but do not quote me on this, test it.  In this
> case, if the timestamp value does not matter, you could simply always write
> with a timestamp of 1.
>
> - LN
>
> On Tue, Sep 21, 2010 at 5:58 AM, Christian Decker <
> decker.christian@gmail.com> wrote:
>
>> Hi all,
>>
>> I have a rather strange problem I'd like to address. As I understand it a
>> write in cassandra always overwrites already existing data, so it is not
>> possible to have a way to create an index pointing to the first entry
>> matching some criteria. What I mean is that I have a CF which stores user
>> purchases and now I want to find the first time a user bought an item from a
>> certain class of objects. For this I was thinking about a CF with SCFs, the
>> CF key being the user ID and the SCF key being the class id of the item and
>> then the value would be the key of the purchase in the purchases CF.
>> Obviously for this to work I'd have to check if a value like
>> firstPurchases[123][987] already exists and if not write it, but it there a
>> way to implement it without the additional read?
>>
>> Regards,
>> Chris
>>
>
>
>
> --
> Lucas J. Nodine
> Assistant Labette County Attorney
> 201 S. Central, Suite B
> Parsons, KS 67357
> (620) 421-6370
>

Mime
View raw message