NOTE: This is part 1 of what will be a two-part series on the performance implications of using in-flight data encryption.

Some of you may recall my security webinar from back in mid-August; one of the follow-up questions that I was asked was about the performance impact of enabling SSL connections. My answer was 25%, based on some 2011 data that I had seen over on yaSSL’s website, but I included the caveat that it is workload-dependent, because the most expensive part of using SSL is establishing the connection. Not long thereafter, I received a request to conduct some more specific benchmarks surrounding SSL usage in MySQL, and today I’m going to show the results.

First, the testing …

We had a wonderful time during the Sept. 25 webinar, “MySQL 5.6 Configuration Optimization,” and I got a lot more questions than I could answer during the hour. So here is a followup with answers to the most interesting questions you guys asked. (You can also watch a recording of entire webinar here.)

Q: What is the impact of having innodb_stats_on_metadata=off in terms of seeing actual table size in information schema ?

A: In MySQL 5.6 this option if off by default. If you disable it in earlier version you will still see the actual table and index sizes as …

The cost of SSDs has been dropping rapidly, and at the time of this writing, 2.5-drives have reached the 1TB capacity mark.  You can actually get inexpensive drives for as little as 60 cents per GB. Even inexpensive SSDs can perform tens of thousands of IOPs and come with 1.5M – 2M hous MTBF and a 5-year warranty: check out the Intel SC S3500 specs as an example. There is however one important factor you need to take into account when considering  SSDs as opposed to conventional hard drives – Write Endurance.

Many of us have heard about SSDs having limits in terms of how many writes SSDs can handle, many however assume this is what is already accounted for in the warranty period and so if the hard drives claim to have sequential write speed of 450MB/sec and a warranty of 5 years we expect …

MySQL DBAs know that integrating MySQL and a big data solution can be challenging. That’s why I invite you to join me this Wednesday (Oct. 2) at 10 a.m. Pacific time for a free webinar in which I’ll walk you through how to implement a successful big data strategy with Apache Hadoop and MySQL. This webinar is specifically tailored for MySQL DBAs and developers (or any person with a previous MySQL experience) who wants to know about how to use Apache Hadoop together with MySQL for Big Data.

The webinar is titled, “Implementing MySQL and Hadoop for Big Data,” and you can register here.

Storing Big Data in MySQL alone can be challenging:

• Single MySQL instance may not …

When innodb_file_per_table is OFF and all data is going to be stored in ibdata files. If you drop some tables of delete some data then there is no any other way to reclaim that unused disk space except dump/reload method.

When Innodb_file_per_table is ON, each table stores data and indexes in it’s own tablespace file. However, the shared tablespace-ibdata1 can still grow and you can check more information here about why it grows and what are the solutions.

http://www.mysqlperformanceblog.com/2013/08/20/why-is-the-ibdata1-file-continuously-growing-in-mysql/

Following the recent blog post from Miguel Angel Nieto titled “ …

This Wednesday in our next webinar I’ll share how to configure a better-performing MySQL 5.6 server. You’ll lean a practical approach to generating a sensible configuration file that sets what is needed and omits what is not.

Why dedicate an entire webinar to the new configuration settings within MySQL 5.6? Mainly because the default configuration files that come with MySQL 5.6 are not designed for high volume production use, and I’ve seen many MySQL incidents caused by poor configuration. Hopefully my advice will save you the headache of tweaking the variables within MySQL’s configuration files in order to work within your organization’s unique business environment.

And while I’ll be …

With the close of call for papers earlier this month, the Percona Live London conference committee was in full swing this past week reviewing all of the many submissions for November’s Percona Live London MySQL Conference.

The submissions are far ranging and cover some really interesting topics, making the lineup for Percona Live London really strong! What the committee looks for in a submission is how much “value” a talk will bring to the conference – this is to say it needs to be far more that a product demo. As such, real-world experiences are receiving much more favorable reviews, along with talks that cover methodologies the attendees will …

One type of question we get very often (even in the form of filed bugs!) is how to switch from stock MySQL to Percona Server or switch from Percona Server 5.5 to Percona XtraDB Cluster using yum, but à la apt-get, i.e. having yum handle the replace.

In its simplest form, yum cannot replace a package¹ for another like apt-get does:

# yum -q -q install Percona-XtraDB-Cluster-server
Error: Percona-XtraDB-Cluster-server conflicts with Percona-Server-server-55
Error: Percona-XtraDB-Cluster-client conflicts with Percona-Server-client-55
Error: Percona-XtraDB-Cluster-shared conflicts with Percona-Server-shared-55


One solution for this is to manually uninstall …

Working day to day with Percona Remote DBA customers, we have been facing an issue from time to time when MySQL replication lag is flapping between 0 and XXXXX constantly – i.e. Seconds_Behind_Master is 0 for a few secs, then it’s like 6287 or 25341, again 0 and so on. I would like to note the 5 different scenarios and symptoms of this – some are obvious and some are not really.

1. Duplicate server-ids on two or more slaves.

Symptoms: MySQL error log on a slave shows the slave thread is connecting/disconnecting from a master constantly.
Solution: check whether all nodes in the replication have unique server-ids.

2. Dual-master setup, “log_slave_updates” enabled, server-ids changed.

Scenario: you stop MySQL on the first master, then you stop the second one. …

Being able to configure slaves to be crash-safe is one of the major improvements of MySQL 5.6 with regards to replication. However we noticed confusion on how to enable this feature correctly, so let’s clarify how it should be done.

In short

1. Stop MySQL on slave
2. Add relay_log_info_repository = TABLE and relay_log_recovery = ON in my.cnf
3. Restart MySQL and relax

The gory details

To fully understand why you should change the above settings if you want crash-safe slaves, let’s first look at the reasons why replication can break when a slave crashes.

On a slave, replication involves 2 threads: the IO thread which copies the binary log of the master to a local copy called the relay log and the SQL thread which then executes the queries written in the relay log. The current position of each thread is stored in a file: master.info for the IO thread …