The MySQL Cluster engineering team recently ran a live webinar, available now on-demand demonstrating the ClusterJ and ClusterJPA NoSQL APIs for MySQL Cluster, and how these can be used in building real-time, high scale Java-based services that require continuous availability.

Attendees asked a number of great questions during the webinar, and I thought it would be useful to share those here, so others are also able to learn more about the Java NoSQL APIs.

First, a little bit about why we developed these APIs and why they are interesting to Java developers.

ClusterJ and Cluster JPA

ClusterJ is a Java interface to MySQL Cluster that provides either a static or dynamic domain object model, similar to the data model used by JDO, …

This post follows the previous post, so set up the environment as described there.
In this example we will perform a full table scan (select * from my_data2) and an index scan (select * from my_data2 where userid=1).

The complete code is here from Severalnines.

Performing a full table scan (no search criteria)
Make sure you have records in the table my_data2.
To perform reads by primary key, we can just use Session::find(..), but here we will do a full table scan.

QueryBuilder qb = s.getQueryBuilder();

/*
* Run the query:
*/
List resultList = query.getResultList();
int count=0;

/*
* …

This post follows the previous post, so set up the environment as described there.
In this example we will have a slightly different table with a combined PK.
The complete code is here.

Create the table

The first thing we should do is to create the table we need for this example:

CREATE TABLE `my_data2` (
`userid` bigint(20) NOT NULL DEFAULT '0',
`friendid` bigint(20) NOT NULL DEFAULT '0',
`data` varbinary(255) DEFAULT NULL,
`last_updated` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
PRIMARY KEY (`userid`,`friendid`)
) ENGINE=ndbcluster DEFAULT CHARSET=latin1
/*!50100 PARTITION BY KEY (userid) */

Mapping …

Cluster/J is a the Java direct API to MySQL Cluster which means it bypasses the MySQL Server and executes requests directly on the data nodes of MySQL Cluster. This gives very good performance (typically >2x faster than SQL) and low latency.

In this blog I will present how to get started and how to do simple lookups.

The complete source code (actually a bit extended to show batching) for this example can be found at Severalnines (here). The code you will see below is just snippets.

Environment

To start with you need MySQL Cluster up and running.
For development on localhost then you can get a sandbox from Severalnines.
If you want to have a test/production environment you …

In a project Severalnines is engaged in, we are developing a realtime application based on Cluster/J. To start with, I must say cluster/j is fantastic and so far I am very happy with it and beaten our expectations big time. It is quite new however and we stumbled on a couple of issues, but those were fixed very fast by the Cluster/J developers. The bugs we encountered were:

• bug 59942
• bug 59941
  

Both which were worked around, and really we never did need to have a binary or a varbinary as the PK, we used a

Performance is great - we have two data nodes (nehalem, 32GB RAM, 146GB SAS 10K disk, 2x4 core 2.4GHz (E5620) ) and two application hosts (same spec, less RAM as data …

If you want to try out the beta features in MySQL Cluster 7.1 then you can either use the appropriate binaries or you can build it for yourself from source. Here I explain how to do this on LINUX.

Note that if you want to make use of OpenJPA then you first need to install OpenJPA and Connector/J.

The example here was on Fedora12 with the MySQL Cluster 7.1.2 source:

CFLAGS=”-O3″ CXX=gcc CXXFLAGS=”-O3 -felide-constructors -fno-exceptions -fno-rtti” ./configure -prefix=/usr/local/mysql –enable-assembler –with-mysqld-ldflags=-all-static –with-plugins=max –with-openjpa …

ClusterJ Architecture

MySQL have been working on a new way of accessing MySQL Cluster using Java. The aim being to give most of the performance of the C++ NDB API but in a much friendlier form for Java developers. There will in fact be 2 new interfaces – ClusterJ (MySQL’s own API) and a JPA solution (using OpenJPA). If you want to see for yourself then take a look at the Blog entry from Bernhard Ocklin – the engineering manager responsible for this work.