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From Paul Chandler <p...@redshots.com>
Subject Re: cass-2.2 trigger - how to get clustering columns and value?
Date Thu, 11 Apr 2019 09:25:22 GMT
Hi Carl,

I now this is not exactly answering your question, but it may help with the split.

I have split a multi tenancy  cluster several times using a similar process to TLP’s Data
Centre Switch: http://thelastpickle.com/blog/2019/02/26/data-center-switch.html

However instead of phase 3, we have split the cluster, by changing the seeds definition to
only point at nodes within their own DC, and change the cluster name of the new DC. This last
step does require a short downtime of the cluster.

We have had success with this method, and if you are only want to track the updates to feed
into the new cluster, this this will work, however it you want it for anything else then it
doesn’t help at all.

I can supply more details later if this method is of interest. 

Thanks 

Paul Chandler 

> On 10 Apr 2019, at 22:52, Carl Mueller <carl.mueller@smartthings.com.INVALID> wrote:
> 
> We have a multitenant cluster that we can't upgrade to 3.x easily, and we'd like to migrate
some apps off of the shared cluster to dedicated clusters.
> 
> This is a 2.2 cluster.
> 
> So I'm trying a trigger to track updates while we transition and will send via kafka.
Right now I'm just trying to extract all the data from the incoming updates
> 
> so for 
> 
>     public Collection<Mutation> augment(ByteBuffer key, ColumnFamily update) {
> 
> the names returned by the update.getColumnNames() for an update of a table with two clustering
columns and had a regular column update produced two CellName/Cells: 
> 
> one has no name, and no apparent raw value (bytebuffer is empty)
> 
> the other is the data column. 
> 
> I can extract the primary key from the key field
> 
> But how do I get the values of the two clustering columns? They aren't listed in the
iterator, and they don't appear to be in the key field. Since clustering columns are encoded
into the name of a cell, I'd imagine there might be some "unpacking" trick to that. 


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