Many MySQL users are familiar with using slow query logs and tools such as mysqldumpslow to identify poor-performing SQL commands, and MySQL 5.6 introduces new powerful tools in PERFORMANCE_SCHEMA.  Both allow you to identify the date/time and the user account from which the command was issued, which is helpful – but if you’re using MySQL Enterprise Monitor (MEM), you can immediately identify the actual line of code responsible for the SQL command in question.  This happens to be one of my favorite and powerful features of MEM, but it’s frequently overlooked by new and experienced MEM users alike, so I’m writing the post to highlight it.

MySQL Enterprise Monitor, of course, is a commercial product that’s part of the MySQL Enterprise subscription.  But it’s freely-available under 30-day trial terms for evaluation from Oracle Software Delivery Cloud – if …

The last MySQL User Group NL meeting was last Friday. It's always nice to learn about MySQL and meet other MySQL users. There were two presentations: one about MySQL User Defined Functions (UDF's) and one about MySQL TCO. The slides are available from the meetup page.

There are already a number of MySQL events announced for the next few months. I'll only list events in the Netherlands and Virtual events.

MySQL Virtual Developer Days
This is a virtual event which will take place on March 19 (EMEA region, NA event is on March 12). There are many interesting topics: Performance Schema, New 5.6 Features, Replication, MySQL Enterprise Monitor
The eVite

SkySQL and MariaDB roadshow
21 March 2013 in Amsterdam
This event  have …

In the majority of MySQL replication scenarios, you want your slave databases to be a mirror of your master databases. You usually don’t want your slave to be behind your master by more than a few seconds – and your main goal is for your slave to always be in sync with your master. Would you ever want your slave to deliberately be a few seconds, minutes or even hours behind your master? There have been several suggestions from MySQL users over the years regarding this functionality as “feature request” (even though most of the requests were submitted as MySQL “bugs”, which was the easiest way to submit such a request).

The first request (that I could find) was by Jason Garrett, back in August of 2006, and was logged as “bug 21639″. Jason wanted MySQL to “provide a parameter/setting which allows an administrator to specify how many seconds a replication …

Last week I had an enlightening experience. It may sound strange, but I found I have super powers... let me explain.

I had a meeting with a big customer of mine to show the value of MySQL Enterprise and Cluster CGE and to share with them the latest and greatest features available in our commercial offerings. During the discussion I said: "Imagine if your MySQL database has a problem at 3pm. Thanks to My Oracle Support and MySQL Enterprise Monitor you can quickly resolve your issues and restore the service".

Well, this is exactly what happened at 2.50pm... I missed the prophecy by just 10m and found I have super powers!

You could imagine how happy the …

We have setup our database servers to log all slow queries > 2 seconds. This can be done by enabling below from your configuration file or via runtime using SET GLOBAL command.

Append to configuration (my.cnf) under [mysqld]

slow_query_log = on
long_query_time = 2

Using query

SET GLOBAL slow_query_log = on;
SET GLOBAL long_query_time = 2

With this current setup, we filtered all queries from our application running more than 2 seconds. This is a good way to identify slow queries and optimise them.

However, there are also queries from the MySQL Enterprise monitor that were also being logged. In this case, i found out a (2) graph metrics checking every minute for the total backup time (total_time) and total lock time (lock_time). It takes about 3-6 seconds with only about 70 records on table.

To …

First of all, I wish you a happy new year.
Many things happened last year, it was really exciting to be involved in the MySQL ecosystem.
I hope this enthusiasm will be increased this year, up to you !

To start the year, I propose the MySQL[plus] Awards 2011
It will only take 5 minutes to fill out these polls.
Answer with your heart first and then with your experience with some of these tools or services.

Polls will be closed January 31, so, vote now !
For “other” answers, please,  let me a comment with details.

Don’t hesitate to submit proposal for tools or services in the comments.
And, please, share these polls !

Note: There is a poll embedded within this post, …

Regardless of the monitoring tool you use to monitor your databases, it can be better to monitor this tool.
No, it’s not a joke ! Do you think you can have a benefit with a monitoring tool not connected to your servers ? ( without being alerted )

I choose to talk about MONyog here but this can apply to all existing monitoring tools.
I just want to share the message, the tool does not matter, so, do it !

So, let me explain how to control if you have fresh data with MONyog.
With MONyog it’s easy because it’s an agentless monitoring tool.

There are two ways to check that :

Per server general info :

For each server, you can …

I was giving a presentation of the MySQL’s Enterprise Monitor* application to a client recently. I was demonstrating the “graphs” section of MEM, where you can monitor MySQL sessions, connections, replication latency and more with 60+ graphs. Usually, you view the graphs from within the MEM Enterprise Dashboard (via a web browser). But the client asked if there was a way to automatically download graphs. I wasn’t sure why he wanted to download the graphs (I didn’t ask), but I knew it wasn’t possible by using MEM alone. However, in the past I have written Perl scripts to automatically download files from web sites, so I thought I would see if it was possible with MEM.

I was speaking with a MySQL customer last week and he had a feature request for MEM. He wants different servers to have different threshold values for certain MEM advisor rules and suggests that users be allowed to override the thresholds when scheduling the rule against a server – just as you can with the refresh interval. At the moment they work around this by creating multiple duplicates of the same rule and then set different thresholds in each. This is a good feature request but in the mean-time this post explains an alternate workaround – having the rules act on thresholds that are defined within the databases of the individual serves.

Step 1. Create a new threshold table in each MySQL Server

The table should be created and then a row added for each rule that needs a per-server threshold:

mysql> create database clusterdb;use clusterdb;
mysql> CREATE TABLE thresholds (name VARCHAR(50) NOT NULL PRIMARY KEY, …

Data Node Restarted alert

About 11 months ago I described the MySQL Cluster functionality that was added to MySQL Enterprise Monitor 2.3; this new post is intended to just bring this up to date – briefly describing the new graph and advisors which have been added since then (up to and including MEM 2.3.7).

Cluster Data Node Has Been Restarted

This new alert flags when a data node has been restarted (by default it alerts on any data node that has started in the last 10 minutes but you can change that interval if you wish). If you manually perform a restart (e.g. as part of a rolling upgrade) then you can safely ignore this alert (or you may even want to temporarily unschedule …