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From Sylvain Lebresne <sylv...@datastax.com>
Subject Re: sstable writer and creating bytebuffers
Date Tue, 31 Mar 2015 07:17:36 GMT
On Tue, Mar 31, 2015 at 7:42 AM, Peer, Oded <Oded.Peer@rsa.com> wrote:

>  Thanks Sylvain.
>
> Is there any way to create a composite key with only one column in
> Cassandra when creating a table, or should creating a CompositeType
> instance with a single column be prohibited?
>

It's hard to answer without knowing what you are trying to achieve.
Provided I don't misunderstand what you are asking, then yes, it's
technically possible, but it's hard to say how wise that is unless I know
more about your constraints/the reasons you're considering that. Let's say
that in general, if you have only a single column, then there isn't too
much reasons to use a CompositeType.

--
Sylvain


>
>
>
> *From:* Sylvain Lebresne [mailto:sylvain@datastax.com]
> *Sent:* Monday, March 30, 2015 1:57 PM
> *To:* user@cassandra.apache.org
> *Subject:* Re: sstable writer and creating bytebuffers
>
>
>
> No, it's not a bug. In a composite every elements start by a 2 short
> indicating the size of the element, plus an extra byte that is used for
> sorting purposes. A little bit more details can be found in the
> CompositeType class javadoc if you're interested. It's not the most compact
> format there is but changing it would break backward compatibility anyway.
>
>
>
> On Mon, Mar 30, 2015 at 12:38 PM, Peer, Oded <Oded.Peer@rsa.com> wrote:
>
> I am writing code to bulk load data into Cassandra using
> SSTableSimpleUnsortedWriter
>
> I changed my partition key from a composite key (long, int) to a single
> column key (long).
>
> For creating the composite key I used a CompositeType, and I kept using it
> after changing the key to a single column.
>
> My code didn’t work until I changed the way I create the ByteBuffer not to
> use CompositeType.
>
>
>
> The following code prints ‘false’.
>
> Do you consider this a bug?
>
>
>
>               *long* val = 123L;
>
>               ByteBuffer direct = *bytes*( val );
>
>               ByteBuffer composite = CompositeType.*getInstance*(
> LongType.*instance* ).builder().add( *bytes*( val ) ).build();
>
>               System.*out*.println( direct.equals( composite ) );
>
>
>
>
>

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