Thanks for the response!

  So, the best solution I can come up with is catching the
InvalidQueryException and check whether its message contains the phrase
"conflicts with an existing column". Seems to work, but super-ugly.

  I do assume that in general, if a request fails, it does not permanently
change the data in Cassandra, right?

  It would be great if alter-add could have an if-not-exists clause. Would
that be hard to implement?

  I could not find a standard CQL way of asking what columns exist. Did I
miss it? Would it be hard to implement?

  I get that we're only eventually consistent anyway.

  Thanks!

     Best, Oliver

On Mon, Feb 5, 2018 at 5:12 PM, Rahul Singh <rahul.xavier.si...@gmail.com>
wrote:

> Yeah, you can handle the exception — what i meant that it wouldnt cause
> harm to the DB
>
> --
> Rahul Singh
> rahul.si...@anant.us
>
> Anant Corporation
>
> On Feb 5, 2018, 5:07 PM -0500, Oliver Ruebenacker <cur...@gmail.com>,
> wrote:
>
> Well, it does throw an InvalidQueryException if the column already exists.
>
> On Mon, Feb 5, 2018 at 4:44 PM, Rahul Singh <rahul.xavier.si...@gmail.com>
> wrote:
>
>> Since CQL != SQL, there’s isnt a syntatical way. Just run the alter table
>> command and it shouldn't be an issue if its there.
>>
>> --
>> Rahul Singh
>> rahul.si...@anant.us
>>
>> Anant Corporation
>>
>> On Feb 5, 2018, 4:15 PM -0500, Oliver Ruebenacker <cur...@gmail.com>,
>> wrote:
>>
>>
>>      Hello,
>>
>>   What's the easiest way to add a column to a table but only if it does
>> not exist? Thanks!
>>
>>      Best, Oliver
>>
>> --
>> Oliver Ruebenacker
>> Senior Software Engineer, Diabetes Portal
>> <http://www.type2diabetesgenetics.org/>, Broad Institute
>> <http://www.broadinstitute.org/>
>>
>>
>
>
> --
> Oliver Ruebenacker
> Senior Software Engineer, Diabetes Portal
> <http://www.type2diabetesgenetics.org/>, Broad Institute
> <http://www.broadinstitute.org/>
>
>


-- 
Oliver Ruebenacker
Senior Software Engineer, Diabetes Portal
<http://www.type2diabetesgenetics.org/>, Broad Institute
<http://www.broadinstitute.org/>

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