DZone
Thanks for visiting DZone today,
Edit Profile
  • Manage Email Subscriptions
  • How to Post to DZone
  • Article Submission Guidelines
Sign Out View Profile
  • Post an Article
  • Manage My Drafts
Over 2 million developers have joined DZone.
Log In / Join
Refcards Trend Reports Events Over 2 million developers have joined DZone. Join Today! Thanks for visiting DZone today,
Edit Profile Manage Email Subscriptions Moderation Admin Console How to Post to DZone Article Submission Guidelines
View Profile
Sign Out
Refcards
Trend Reports
Events
Zones
Culture and Methodologies Agile Career Development Methodologies Team Management
Data Engineering AI/ML Big Data Data Databases IoT
Software Design and Architecture Cloud Architecture Containers Integration Microservices Performance Security
Coding Frameworks Java JavaScript Languages Tools
Testing, Deployment, and Maintenance Deployment DevOps and CI/CD Maintenance Monitoring and Observability Testing, Tools, and Frameworks
Culture and Methodologies
Agile Career Development Methodologies Team Management
Data Engineering
AI/ML Big Data Data Databases IoT
Software Design and Architecture
Cloud Architecture Containers Integration Microservices Performance Security
Coding
Frameworks Java JavaScript Languages Tools
Testing, Deployment, and Maintenance
Deployment DevOps and CI/CD Maintenance Monitoring and Observability Testing, Tools, and Frameworks
  1. DZone
  2. Data Engineering
  3. Data
  4. CQL, Astyanax and Compound/Composite Keys: Writing Data

CQL, Astyanax and Compound/Composite Keys: Writing Data

Brian O' Neill user avatar by
Brian O' Neill
·
Oct. 12, 12 · Interview
Like (0)
Save
Tweet
Share
8.97K Views

Join the DZone community and get the full member experience.

Join For Free
In my previous post, I showed how to connect the dots between Astyanax and CQL, but it focused primarily on reading.  Here is the update that connects the dots on write.

I created a sample project and put it out on github.  Let me know if you have any trouble.

Extending the previous example to accomodate writes, you need to use the AnnotatedCompositeSerializer when writing as well.  Here is the code:
    public void writeBlog(String columnFamilyName, String rowKey, FishBlog blog, byte[] value) throws ConnectionException {
        AnnotatedCompositeSerializer entitySerializer = new AnnotatedCompositeSerializer(FishBlog.class);
        MutationBatch mutation = keyspace.prepareMutationBatch();
        ColumnFamily columnFamily = new ColumnFamily(columnFamilyName,
                StringSerializer.get(), entitySerializer);
        mutation.withRow(columnFamily, rowKey).putColumn(blog, value, null);
        mutation.execute();
    }
Now, if you recall from the previous post, we had a single object, FishBlog, that represented the compound/composite column name:
public class FishBlog {
    @Component(ordinal = 0)
    public long when;
    @Component(ordinal = 1)
    public String fishtype;
    @Component(ordinal = 2)
    public String field;
}
We mapped this object to the following schema:
    CREATE TABLE fishblogs (
        userid varchar,
        when timestamp,
        fishtype varchar,
        blog varchar,
        image blob,
        PRIMARY KEY (userid, when, fishtype)
    );
We had one member variable in FishBlog, field, that specified which piece of data we were writing: image or blog.  Because of how things work with CQL and the Java API, you actually need *two* mutations to create a row.  Here is the code from the unit test:
       AstyanaxDao dao = new AstyanaxDao("localhost:9160", "examples");
       FishBlog fishBlog = new FishBlog();
       fishBlog.fishtype="CATFISH";
       fishBlog.field="blog";
       fishBlog.when=now;
       dao.writeBlog("fishblogs", "bigcat", fishBlog, "myblog.".getBytes());
       
       FishBlog image = new FishBlog();
       image.fishtype="CATFISH";
       image.field="image";
       image.when = now;
       byte[] buffer = new byte[10];
       buffer[0] = 1;
       dao.writeBlog("fishblogs", "bigcat", image, buffer);

All parts of the primary key need to be the same between the the different mutations.  Then, after you perform both mutations, you'll get a row back in CQL that looks like:
cqlsh:examples> select * from fishblogs;
 userid | when                     | fishtype | blog            | image
--------+--------------------------+----------+-----------------+----------------------
 bigcat | 2012-10-08 12:08:10-0400 |  CATFISH | this is myblog. | 01000000000000000000

Hopefully this clears things up for people.

 

 

 

Relational database Data (computing)

Published at DZone with permission of Brian O' Neill, DZone MVB. See the original article here.

Opinions expressed by DZone contributors are their own.

Popular on DZone

  • The Future of Cloud Engineering Evolves
  • The Quest for REST
  • Java Development Trends 2023
  • A Complete Guide to AngularJS Testing

Comments

Partner Resources

X

ABOUT US

  • About DZone
  • Send feedback
  • Careers
  • Sitemap

ADVERTISE

  • Advertise with DZone

CONTRIBUTE ON DZONE

  • Article Submission Guidelines
  • Become a Contributor
  • Visit the Writers' Zone

LEGAL

  • Terms of Service
  • Privacy Policy

CONTACT US

  • 600 Park Offices Drive
  • Suite 300
  • Durham, NC 27709
  • support@dzone.com
  • +1 (919) 678-0300

Let's be friends: