Connector/J provides a useful load-balancing implementation for Cluster or multi-master deployments.  As of Connector/J 5.1.12, this same implementation is used under the hood for balancing load between read-only slaves with ReplicationDriver.  When trying to balance workload between multiple servers, though, the driver has to decide when it’s safe to swap servers – doing so in the middle of a transaction would not make applications very happy.  Many of the same principles which apply to autoReconnect also apply here – you don’t want to lose important state information.

As a result, Connector/J will only try to pick a new server when one of the following happen:

1. At transaction boundaries (transactions are explicitly committed or rolled back)
2. A communication …

Chances are, if you write Java applications using MySQL’s Connector/J driver, you’ve run across the autoReconnect property.  I remember that when I first found it, it seemed I had found the grail itself.  “No more nasty connection closed error messages,” I thought.  Except … it doesn’t really work that way, does it?  I’ve seen this question asked many times in many different contexts:  “Why doesn’t Connector/J just reconnect to MySQL and re-issue my statement, instead of throwing this Exception?”

There are actually a number of reasons, starting with loss of transactional integrity.  The …

OK, you found the problem SQL statement that was affecting your server’s performance, now where did it originate?

The new MySQL Enterprise Plugins for Connector/J and Connector/NET send query statistics, including the source location for each query, directly to the MySQL Enterprise Monitor.

Figure 1 is a screenshot of new source location feature.

Figure 1. Source Location

Figure 2 shows the standard query statistics, which are collected in the query analyzer.  In both cases, the statistics are gathered by the MySQL Connector and the Plugin, not MySQL proxy.

Figure 2. Query Analyzer

If you’re a MySQL Enterprise customer, you can …

OpenSQLCamp was a huge success! Not many folks have blogged about what they learned there….if you missed it, all is not lost. We did take videos of most of the sessions (we only had 3 video cameras, and 4 rooms, and 2 sessions were not recorded).

All the videos have been processed, and I am working on uploading them to YouTube and filling in details for the video descriptions. Not all the videos are up right now….right now all the lightning talks are up.

• 
  
• All the lightning talks belowin one continuous video (just over 54 minutes total)
  
• The Graph Engine (Antony Curtis)
  
• …

A new technical article entitled "Using the MySQL Connector/J JDBC Driver With the Java SE Platform", has been posted on java.sun.com at:

        http://java.sun.com/developer/technicalArticles/mysql_java/index.html

This article explains the essential steps involved in accessing/manipulating the data in a MySQL database from a Java application. MySQL Connector/J JDBC driver was used in the example code to show the database connectivity, data manipulation steps. Application developers who are new to Java programming language [but not to MySQL database] are the target audience of this article.

Stay tuned for the next article in this series "Using MySQL with PHP" ..

A new technical article entitled "Using the MySQL Connector/J JDBC Driver With the Java SE Platform", has been posted on java.sun.com at:

        http://java.sun.com/developer/technicalArticles/mysql_java/index.html

This article explains the essential steps involved in accessing/manipulating the data in a MySQL database from a Java application. MySQL Connector/J JDBC driver was used in the example code to show the database connectivity, data manipulation steps. Application developers who are new to Java programming language [but not to MySQL database] are the target audience of this article.

Stay tuned for the next article in this series "Using MySQL with PHP" ..

A new technical article entitled "Using the MySQL Connector/J JDBC Driver With the Java SE Platform", has been posted on java.sun.com at:

        http://java.sun.com/developer/technicalArticles/mysql_java/index.html

This article explains the essential steps involved in accessing/manipulating the data in a MySQL database from a Java application. MySQL Connector/J JDBC driver was used in the example code to show the database connectivity, data manipulation steps. Application developers who are new to Java programming language [but not to MySQL database] are the target audience of this article.

Stay tuned for the next article in this series "Using MySQL with PHP" ..