High availability is about more than just making sure that applications can get to your data, even if there is a failure:

How about when you are upgrading your database schema What if you need to add memory to a database server or reconfigure/restart MySQL If your apps want to read data from a MySQL slave, how can you be sure they are not reading stale data without re-coding your apps What

Oracle is the most powerful database system in the world. However, Oracle's expensive and complex replication makes it difficult to build highly available applications or move data in real-time to data warehouses and popular databases like MySQL.

In this video (recording of our 9/13/12 webinar) you will learn how Continuent Tungsten solves problems with Oracle replication at a fraction of the

After a long pause in the speaking game, I am back.

It's since April that I haven't been on stage, and it is now time to resume my public duties.

• I will speak at MySQL Connect in San Francisco, just at the start of Oracle Open World, with a talk on MySQL High Availability: Power and Usability. It is about the cool technology that is keeping me busy here at Continuent, which can make life really easy for DBAs. This talk will be a demo fest. If you are attending MySQL Connect, you should see it!
• A happy return for me. On October 27th I will talk about open source databases and the pleasures of command line operations at …

In this blog post I will show you how to setup a replication from MySQL Cluster  (ndbcluster) to a regular MySQL Server (InnoDB). If you want to understand the concepts, check out part 7 of our free MySQL Cluster training.

First of all we start with a MySQL Cluster looking like this, and what we want to do is to setup replication server to the Reporting Server (InnoDB slave).




MySQL Cluster is great at scaling large numbers of write transactions or shorter key-based read querise, but not so good at longer reporting or analytical queries. I generally recommend people to limit analytical/reporting queries on the MySQL Cluster, in order to avoid slowing down the …

Oracle is the most powerful database system in the world. However, Oracle's expensive and complex replication makes it difficult to build highly available applications or move data in real-time to data warehouses and popular databases like MySQL.

In this webinar you will learn how Continuent Tungsten solves problems with Oracle replication at a fraction of the cost of other solutions and

Coming from the MySQL world, I’m used to being able to easily determine the replication delay (in seconds) via the SHOW SLAVE STATUS command: mysql> show slave status\G *************************** 1. row *************************** ... Seconds_Behind_Master: 0 ... 1 row in set (0.00 sec) Unfortunately, there is no such comparable command in PostgreSQL. The official docs propose [...]

Why is it so important to close connections to databases if there’s no explicit need to keep them open (which usually the case)?

Symptoms

• Icinga reports high usage of allowed connections (>90%) on master MySQL server.
• No running queries or any specific in processlist. All the connections are sleeping from the same servers.
• The number of connections was 20 times more than the usual

Root cause

There was tremendous amount of queries doing “copying to tmp table” on the slaves. The connections were opened to both master and slaves and waiting for the slaves to answer the query the connections to master was kept opened. So the sleeping connections was piled up to the limit of max connections.

Lesson

1. When troubleshooting always check slaves too.
2. Close unused connections especially for masters.
3. Keep your query optimized and …

If you ever had a replication slave that is severely behind, you probably noticed that it’s not catching up with a busy master at a steady pace. Instead, the “Seconds behind master” is going up and down so you can’t really tell whether the replica is catching up or not by looking at just few samples, unless these are spread apart. And even then you can’t tell at a glance when it is going to catch up.

Normally, the “severely behind” thing should not happen, but it does often happen in our consulting practice:

• sometimes replication would break and then it needs to catch up after it is fixed,
• other times new replication slave is built from a backup which is normally hours behind,
• or, it could be that replication slave became too slow to catch up due to missing index

Whatever the case is, single question I am being asked by the customer every time this happens is this: …

MySQL data rules the cloud, but recent experience shows us that there's no substitute for maintaining copies of data, across availability zones, when it comes to Amazon Web Services (AWS) data resilience.

In this video (recording of our 8/23/12 webcast), we survey technologies for maintaining real-time copies of your data and the pros & cons of each. We conclude with a live demonstration of a

There has been a lot of talk about MySQL 5.6 replication improvements. With few exceptions, what I have seen was either marketing messages or hearsay. This means that few people have really tried out the new features to see whether they meet the users needs.

As usual, I did try the new version in my environment. I like to form my own opinion based on experiments, and so I have been trying out these features since they have appeared in early milestones.

What follows is a list of (potentially) surprising results that you may get when using MySQL 5.6.
All the examples are made using MySQL 5.6.6.

Gotcha #1 : too much noise

I have already mentioned that MySQL 5.6 is too verbose when creating data directory. This also means that your error log may have way more information than you'd like to get. …