As you may have heard, this week on December 28, 2011, a group of security experts released information about a nasty problem in almost all languages and platforms related to hash function collisions and possibility of using those for DoS attack on web applications.

Ruby core team released new 1.8.7-p357 version with the problem fixed. JRuby development team came out with the new 1.6.5.1 release. Unfortunately 2 days after the release there is still no information from Ruby Enterprise Edition team on what to do with all the ree deployments.

So, since there is …

Until MySQL 5.5 the only variable used to identify a network connectivity problem between Master and Slave was slave-net-timeout. This variable specifies the number of seconds to wait for more Binary Logs events from the master before abort the connection and establish it again. With a default value of 3600 this has been a historically bad configured variable and stalled connections or high latency peaks were not detected for a long period of time or not detected at all. We needed an active master/slave connection check. And here is where replication’s heartbeat can help us.

This feature was introduce in 5.5 as another parameter to the CHANGE MASTER TO command. After you enable it, the MASTER starts to send “beat” packages (of 106 bytes) to the SLAVE every X seconds where X is a value you can define. If the network link goes down or the latency goes up for more than the time …

Overview

Profiling, analyzing and then fixing queries is likely the most oft-repeated part of a job of a DBA and one that keeps evolving, as new features are added to the application new queries pop up that need to be analyzed and fixed. And there are not too many tools out there that can make your life easy. However, there is one such tool, pt-query-digest (from Percona Toolkit) which provides you with all the data points you need to attack the right query in the right way. But vanilla MySQL does have its limitations, it reports only a subset of stats, however if you compare that to Percona server, it reports extra stats such as information about the queries’ execution plan (which includes things like whether Query cache was used or not, if Filesort was used, whether tmp table was created in memory or on disk, if full scan was done, etc) as well as InnoDB …

How much memory does my Oracle instance use? How much memory do my database connections use?

These are questions that can help with capacity planning of your server’s Physical and Virtual memory. There are several write ups out there on the web that attempt to address these questions. From what I could gather from them, there is only one truly good way to tell exactly how much memory is currently in use by an oracle instance (or any other system, http, mysql, etc), as well as the average memory usage for oracle dedicated connection processes.

This technique makes use of the “pmap” command. This command displays the real current memory usage of a process broken down by memory segment types. By parsing the output of pmap, we can make several useful calculations. Note that this command is available for Linux, Solaris and HP-UX servers. It is also apparently available on AIX as “procmap”.

I have tested the below …

I see so many posts on what happened to company X, product Y and dream Z that I couldn't resist the temptation to summarize this great year for MySQL. At the end of 2010, Oracle did an announcement we were all waiting for: MySQL 5.5 is GA! Another year has passed since then and it's time to reflect on what has been done.

I know this is a long post. I tried to rewrite it at least 10 times to make it shorter, but I couldn't condense the list. Hence, I wrote a summary in the beginning for those who don't want to read it all.

I believe that 2011 was an exceptional year for MySQL and I really enjoy being part of this team. I wish all of us a lot of success and fun in the years to come!

Summary:
Oracle released many  …

I've been spending some time looking through the new features of MariaDB 5.3, and one of the big items is an improved and configurable optimizer. Much of the functionality of the new optimizer is controlled using the optimizer switch variable [http://kb.askmonty.org/en/mariadb-53-optimizer_switch].

There's been some discussion (see [http://s.petrunia.net/blog/?p=61] and [https://lists.launchpad.net/maria-developers/msg04142.html]) about splitting …

Overview

Profiling, analyzing and then fixing slow queries is likely the most oft-repeated part of a job of a DBA. And there are not too many tools out there that can make your life easy by providing analysis of queries with such data points that allow you to attack the right queries in the right way. One such tool that I have always found myself using is pt-query-digest(formerly known as mk-query-digest).

Now let us go through using this very nice tool.

Before We Start!

But before we start, make sure you have enabled slow query logging and set a low enough long_query_time. The correct value of long_query_time depends on your application …

The MySQL council is looking for candidates for 2012.  Based on community feedback, this will be an open nomination process (and you can nominate yourself).

The MySQL council advocates for the MySQL community, and needs community leaders to help address issues such as keeping the bug database open and keeping the user conference from fragmenting.  The council tries to help solve issues that the community faces with Oracle, IOUG, or anyone else.  The council comprises four to six members representing a mix of consultants, volunteers, community activists, developers, and vendors.  The council is not meant to replace any existing grass roots organizations, rather it may be helpful for gaining visibility for their issues.

As a council member, you would be asked to participate in meetings (they’ve been about once a month by phone, but there may be a face-to-face meeting).  You will also be asked to help …

Recently some customers running on Amazon EC2 asked me how to configure a HA environment for their ScaleBase instance.
For instance, let’s look at the following architecture:

To ensure that Scalebase is not a single point of failure, several ScaleBase instances can be used – so if one crashes, other instances can handle its connections.

This is quite simple to do:

1. Start the EC2 instance to be used for the ScaleBase configuration
   1. Install MySQL on the machine and follow the database preparation instructions defined in the ScaleBase installation guide.
   2. Install ScaleBase with the –mode=ALL parameter.
   3. Create an EC2 instance that will be used as an AMI for all ScaleBase installations.
      1. Download and install ScaleBase …

This guide will get you up and running with how to identify the bottleneck queries using the excellent tool pt-query-digest. You will learn how to use and analyze the output returned by pt-query-digest. You will also learn some differences between slow query logging in various MySQL versions. Later on in the post I will also show you how to make use of the extra diagnostic data available with Percona Server.

The post Profiling your slow queries using pt-query-digest and some love from Percona Server appeared first on ovais.tariq.