MySQL 5.1 is GA with the 5.1.30 ReleaseMySQL 5.1.30 is the GA version of the MySQL 5.1 software version. The 5.1 release has some key features that users are going to like which include:Table and Index PartitioningRow-based and Mixed ReplicationThe embedded libmysqld libraryImproved XML features with additional XPath supportEvent SchedulerUpgraded Advisors for the MySQL Enterprise

Here's a neat tip posted by Henrik Ingo from the MySQL Telecom Team

It's not really properly documented in the manual part, but I found in the changelogs, and confirmed on IRC that to do load-balancing across the SQL nodes in MySQL Cluster, you would use a different JDBC connection string with the "loadbalance" keyword added...

jdbc:mysql:loadbalance://host-1,host-2,...host-n/database?loadBalanceBlacklistTimeout=5000

Anyway, it was verified independently, but there was a catch. The script in the master was using SET storage_engine=InnoDB to create the tables necessary for the test. That looked good enough to me. The script was indeed creating InnoDB tables on the master. The trouble was that the "SET" command is not replicated. Thus the …

Here is a discussion about some caveats with allocation and deallocation of extents in MySQL Cluster (disk data).

Let's assume we have created a table space with one datafile having 5 extents (i.e the datafile is 5MB in since, since the size of each extent is 1MB).

Using the information_schema we can figure out how many free extents we have by executing the following query:

mysql> select free_extents, total_extents from information_schema.files where file_type='datafile';
+--------------+---------------+
| free_extents | total_extents |
+--------------+---------------+
| 5 | 5 |
| 5 | 5 |
+--------------+---------------+

The figure below shows a number of extents that are all free.
…

Last week I helped a customer setup a JBoss application against MySQL Cluster. It turns out it is not immediately obvious how you should setup our JDBC connector to do loadbalancing and failover. For instance, setting the connector up for an Master-Slave setup (with MySQL Enterprise) is well documented, but not doing the same with MySQL Cluster.

It's not really properly documented in the manual part, but I found in the changelogs, and confirmed on IRC that to do load-balancing across the SQL nodes in MySQL Cluster, you would use a different JDBC connection string with the "loadbalance" keyword added...

jdbc:mysql:loadbalance://host-1,host-2,...host-n/database

That does indeed …

Hi all,

Today I'd like to continue a blog series in which I highlight Web application tutorials for NetBeans 6.5. A few changes have been made to tutorials, among which is the featuring of MySQL as the database of choice.

This fourth entry in the series will cover the tutorial, "Using Databound Components to Access a Database".

In this tutorial, you use NetBeans IDE 6.5 to create and deploy a web application that displays master-detail data from a database that is packaged with the IDE. In the application, you select a person from a JSF 1.2 (Woodstock) drop-down list, and the application displays a table that shows all the trip records for that person.

MySQL is the database used in this version of the tutorial.

A new look to an existing tutorial. Be sure to check this one out.

…

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Last week I helped a customer setup a JBoss application against MySQL Cluster. It turns out it is not immediately obvious how you should setup our JDBC connector to do loadbalancing and failover. For instance, setting the connector up for an Master-Slave setup (with MySQL Enterprise) is well documented, but not doing the same with MySQL Cluster.

It's not really properly documented in the manual part, but I found in the changelogs, and confirmed on IRC that to do load-balancing across the SQL nodes in MySQL Cluster, you would use a different JDBC connection string with the "loadbalance" keyword added...

jdbc:mysql:loadbalance://host-1,host-2,...host-n/database

That does indeed …

Last week I helped a customer setup a JBoss application against MySQL Cluster. It turns out it is not immediately obvious how you should setup our JDBC connector to do loadbalancing and failover. For instance, setting the connector up for an Master-Slave setup (with MySQL Enterprise) is well documented, but not doing the same with MySQL Cluster.

It's not really properly documented in the manual part, but I found in the changelogs, and confirmed on IRC that to do load-balancing across the SQL nodes in MySQL Cluster, you would use a different JDBC connection string with the "loadbalance" keyword added...

jdbc:mysql:loadbalance://host-1,host-2,...host-n/database

That does indeed …

Selecting rows holding group-wise maximum is a favorite problem of mine, but one which only rarely pops up. But for some reason, after my last blog post on the subject, it seems to be mentioned almost daily around here.

Something that I forgot to mention in the previous post is that most of the examples there assume suitable indexing is available to get decent performance. Basically a composite index on both the column(s) in the GROUP BY and the column over which MAX is computed is needed. In the example I gave, such an index is available throught the primary key.

However, such an index may not be available in all cases. Maybe maintaining it would be too expensive, or maybe the data the max is computed over is itself the result of a (sub-)query, and no indexing is available. So it is worth it also to understand this case, as the performance of the …