triggers in cassandra

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triggers in cassandra

Hector Yuen
Hi all,

I am just starting to use Cassandra, and I was wondering if it is possible to use triggers/ callbacks on columns so that they get notified when there is a change.

Is there such functionality?

Thanks

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-h
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Re: triggers in cassandra

Eric Evans-4
On Fri, 2009-09-25 at 02:17 -0700, Hector Yuen wrote:
> I am just starting to use Cassandra, and I was wondering if it is
> possible
> to use triggers/ callbacks on columns so that they get notified when
> there
> is a change.
>
> Is there such functionality?

No, there isn't. Someone was working on this at some point, but it
wasn't going anywhere so it got removed
(http://svn.apache.org/viewvc?view=rev&revision=806267).

--
Eric Evans
[hidden email]

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Re: triggers in cassandra

Michael Greene
Hector,

Can you describe explicitly what you'd want to see from callouts/triggers?  One of the reasons I advocated for removal is that no one had a need for it or was working on it in the open source project.  What's your scenario?

Michael

On Fri, Sep 25, 2009 at 9:40 AM, Eric Evans <[hidden email]> wrote:
On Fri, 2009-09-25 at 02:17 -0700, Hector Yuen wrote:
> I am just starting to use Cassandra, and I was wondering if it is
> possible
> to use triggers/ callbacks on columns so that they get notified when
> there
> is a change.
>
> Is there such functionality?

No, there isn't. Someone was working on this at some point, but it
wasn't going anywhere so it got removed
(http://svn.apache.org/viewvc?view=rev&revision=806267).

--
Eric Evans
[hidden email]


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Re: triggers in cassandra

Hector Yuen
Michael,

What I want to do is to use a column as a place for keeping state between different clients.

I would register callbacks for a column, so when there is any other guy changing the data I can get notified. That way I don't need to do continuous polling.

Is there any functionality right now that I could use to implement this?

Thanks
-h

On Fri, Sep 25, 2009 at 7:59 AM, Michael Greene <[hidden email]> wrote:
Hector,

Can you describe explicitly what you'd want to see from callouts/triggers?  One of the reasons I advocated for removal is that no one had a need for it or was working on it in the open source project.  What's your scenario?

Michael


On Fri, Sep 25, 2009 at 9:40 AM, Eric Evans <[hidden email]> wrote:
On Fri, 2009-09-25 at 02:17 -0700, Hector Yuen wrote:
> I am just starting to use Cassandra, and I was wondering if it is
> possible
> to use triggers/ callbacks on columns so that they get notified when
> there
> is a change.
>
> Is there such functionality?

No, there isn't. Someone was working on this at some point, but it
wasn't going anywhere so it got removed
(http://svn.apache.org/viewvc?view=rev&revision=806267).

--
Eric Evans
[hidden email]





--
-h
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Re: triggers in cassandra

Jonathan Ellis-3
That's a bad fit for Cassandra, since the machine any given client
talks to is unlikely to be the machine that data got sent to.  So
you'd have to send the notifications from

Client1 -> cassandra1 -> cassandra data node -> cassandra2 -> client 2

It would complicate things significantly.

-Jonathan

On Fri, Sep 25, 2009 at 12:21 PM, Hector Yuen <[hidden email]> wrote:

> Michael,
>
> What I want to do is to use a column as a place for keeping state between
> different clients.
>
> I would register callbacks for a column, so when there is any other guy
> changing the data I can get notified. That way I don't need to do continuous
> polling.
>
> Is there any functionality right now that I could use to implement this?
>
> Thanks
> -h
>
> On Fri, Sep 25, 2009 at 7:59 AM, Michael Greene <[hidden email]>
> wrote:
>>
>> Hector,
>> Can you describe explicitly what you'd want to see from callouts/triggers?
>>  One of the reasons I advocated for removal is that no one had a need for it
>> or was working on it in the open source project.  What's your scenario?
>> Michael
>>
>> On Fri, Sep 25, 2009 at 9:40 AM, Eric Evans <[hidden email]> wrote:
>>>
>>> On Fri, 2009-09-25 at 02:17 -0700, Hector Yuen wrote:
>>> > I am just starting to use Cassandra, and I was wondering if it is
>>> > possible
>>> > to use triggers/ callbacks on columns so that they get notified when
>>> > there
>>> > is a change.
>>> >
>>> > Is there such functionality?
>>>
>>> No, there isn't. Someone was working on this at some point, but it
>>> wasn't going anywhere so it got removed
>>> (http://svn.apache.org/viewvc?view=rev&revision=806267).
>>>
>>> --
>>> Eric Evans
>>> [hidden email]
>>>
>>
>
>
>
> --
> -h
>
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Re: triggers in cassandra

Michael Greene
Additionally, Cassandra client connections and the Thrift API are not designed to be stateful.  For what it's worth, Apache Zookeeper offers such change notifications, but has a very different architecture.

Michael

On Fri, Sep 25, 2009 at 12:25 PM, Jonathan Ellis <[hidden email]> wrote:
That's a bad fit for Cassandra, since the machine any given client
talks to is unlikely to be the machine that data got sent to.  So
you'd have to send the notifications from

Client1 -> cassandra1 -> cassandra data node -> cassandra2 -> client 2

It would complicate things significantly.

-Jonathan

On Fri, Sep 25, 2009 at 12:21 PM, Hector Yuen <[hidden email]> wrote:
> Michael,
>
> What I want to do is to use a column as a place for keeping state between
> different clients.
>
> I would register callbacks for a column, so when there is any other guy
> changing the data I can get notified. That way I don't need to do continuous
> polling.
>
> Is there any functionality right now that I could use to implement this?
>
> Thanks
> -h
>
> On Fri, Sep 25, 2009 at 7:59 AM, Michael Greene <[hidden email]>
> wrote:
>>
>> Hector,
>> Can you describe explicitly what you'd want to see from callouts/triggers?
>>  One of the reasons I advocated for removal is that no one had a need for it
>> or was working on it in the open source project.  What's your scenario?
>> Michael
>>
>> On Fri, Sep 25, 2009 at 9:40 AM, Eric Evans <[hidden email]> wrote:
>>>
>>> On Fri, 2009-09-25 at 02:17 -0700, Hector Yuen wrote:
>>> > I am just starting to use Cassandra, and I was wondering if it is
>>> > possible
>>> > to use triggers/ callbacks on columns so that they get notified when
>>> > there
>>> > is a change.
>>> >
>>> > Is there such functionality?
>>>
>>> No, there isn't. Someone was working on this at some point, but it
>>> wasn't going anywhere so it got removed
>>> (http://svn.apache.org/viewvc?view=rev&revision=806267).
>>>
>>> --
>>> Eric Evans
>>> [hidden email]
>>>
>>
>
>
>
> --
> -h
>

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Re: triggers in cassandra

Hector Yuen-2
Michael

I will check that out

Thanks

On Fri, Sep 25, 2009 at 10:35 AM, Michael Greene <[hidden email]> wrote:
Additionally, Cassandra client connections and the Thrift API are not designed to be stateful.  For what it's worth, Apache Zookeeper offers such change notifications, but has a very different architecture.

Michael


On Fri, Sep 25, 2009 at 12:25 PM, Jonathan Ellis <[hidden email]> wrote:
That's a bad fit for Cassandra, since the machine any given client
talks to is unlikely to be the machine that data got sent to.  So
you'd have to send the notifications from

Client1 -> cassandra1 -> cassandra data node -> cassandra2 -> client 2

It would complicate things significantly.

-Jonathan

On Fri, Sep 25, 2009 at 12:21 PM, Hector Yuen <[hidden email]> wrote:
> Michael,
>
> What I want to do is to use a column as a place for keeping state between
> different clients.
>
> I would register callbacks for a column, so when there is any other guy
> changing the data I can get notified. That way I don't need to do continuous
> polling.
>
> Is there any functionality right now that I could use to implement this?
>
> Thanks
> -h
>
> On Fri, Sep 25, 2009 at 7:59 AM, Michael Greene <[hidden email]>
> wrote:
>>
>> Hector,
>> Can you describe explicitly what you'd want to see from callouts/triggers?
>>  One of the reasons I advocated for removal is that no one had a need for it
>> or was working on it in the open source project.  What's your scenario?
>> Michael
>>
>> On Fri, Sep 25, 2009 at 9:40 AM, Eric Evans <[hidden email]> wrote:
>>>
>>> On Fri, 2009-09-25 at 02:17 -0700, Hector Yuen wrote:
>>> > I am just starting to use Cassandra, and I was wondering if it is
>>> > possible
>>> > to use triggers/ callbacks on columns so that they get notified when
>>> > there
>>> > is a change.
>>> >
>>> > Is there such functionality?
>>>
>>> No, there isn't. Someone was working on this at some point, but it
>>> wasn't going anywhere so it got removed
>>> (http://svn.apache.org/viewvc?view=rev&revision=806267).
>>>
>>> --
>>> Eric Evans
>>> [hidden email]
>>>
>>
>
>
>
> --
> -h
>




--
-h