Ideas, releases, practical guides, and perspectives from the people building with MySQL.
After many months of heavy development and testing, Debian 8 (Jesse) and Ubuntu 15.04 (Vivid Vervet) were released recently.
For those who already upgraded their systems and/or plan do do it in close future, we prepared builds of WebScaleSQL :-)
You can also install it using PSCE repository.
I have recently seen several cases when performance for MySQL queries on a single table was terrible. The reason was simple: the wrong indexes were added and so the execution plan was poor. Here are guidelines to help you optimize various kinds of single-table queries.
Disclaimer: I will be presenting general guidelines and I do
not intend to cover all scenarios. I am pretty confident that you
can find examples where what I am writing does not work, but I am
also confident that it will help you most of the time. Also I
will not discuss features you can find in MySQL 5.6+ like Index
Condition Pushdown to keep things simple. Be aware that such
features can actually make a significant difference in query
response time (for good or for bad).
What an index can do for you
An index can perform up to 3 actions: filter, sort/group and cover. While the first 2 actions are self-explanatory, not everyone may know what …
[Read more]On Tuesday Steaphan Greene announced that all currently-pushed changes have now been rebased onto the newly-released upstream MySQL-5.6.24.
The new branch at this point is available on github.
Our .deb and .rpm builds are available in the PSCE repo as well as being browsable here http://repo.psce.com/download/webscalesql/
Instructions for using the repo are available for Debian …
[Read more]In Mo’ Data, Mo’ Problems, we explored the paradox that “Big Data” projects pose to organizations and how Tokutek is taking an innovative approach to solving those problems. In this post, we’re going to talk about another hot topic in IT, “The Cloud,” and how enterprises undertaking Cloud efforts often struggle with idea of “problem trading.” Also, for some reason, databases are just given a pass as traditionally “noisy neighbors” and that there is nothing that can be done about it. Lets take a look at why we disagree.
With the birth of the information age came a coupling of business and IT. Increasingly strategic business projects and objectives were reliant on information infrastructure to provide information storage and retrieval instead of paper and filing cabinets. This was the dawn of the database and what gave rise to companies like Oracle, Sybase and MySQL. With the appearance of true Enterprise Grade …
[Read more]Driven by popularity of previous post about Debian/Ubuntu builds of WebScaleSQL and long discussions during FOSDEM conference this weekend, PSCE engineering team decided to put even more effort into.
We would like to introduce:
Architectures covered:
Please note that “WebScaleSQL does not currently maintain compatibility for anything except GNU/Linux x86_64.” (WebScaleSQL FAQ)”
RedHat/CentOS releases:
Packages can be downloaded from …
[Read more]We have been looking at the WebScaleSQL project with great excitement. As with any new enhancements to the MySQL world, we need to test extensively to ensure we can give PSCE customers the best advice possible. Since this project is source only, we decided to add WebScaleSQL builds to our repo, so we could examine the changes being introduced by all the different collaborators.
So what is WebscaleSQL?
WebScaleSQL is a collaboration among engineers from several companies that face the same challenges in deploying MySQL at scale, and seek greater performance from a database technology tailored for their needs.
— WebScaleSQL, Frequently Asked Questions
What makes this project so special, is the level of collaboration between some of the most …
[Read more]Welcome to blog #2 in a series about the benefits of the Fractal Tree. In this post, I’ll be explaining Big Data, why it poses such a problem and how Tokutek can help. Given the fact that I am a lifelong fan of both Hip-hop and Big Data, the title was a no-brainer and, given the artist, a bit of a pun.
I am as tired as you of hearing the term “Big Data.” It’s so overused, that it ceases to have specific meaning anymore. You see, data hardly ever starts as “big” or a “problem.” Rather, it starts small and easily manageable, but gradually grows to some unimaginable size and becomes a beast in need of slaying, like the irradiated ant from a sci-fi film, growing to the size of a cruise ship. The nature of tackling such a tough problem means that the initial understanding of the factors involved is, oftentimes, incomplete at best; Catch-22 exemplified. During the course of problem it is …
[Read more]Long running transactions can be problematic for OLTP workloads, particularly where we would expect most to be completed in less than a second. In some cases a transaction staying open just a few seconds can cause behaviour that is entirely unexpected, with the developers at a loss as to why a transaction remained open. There are a number of ways to find long running transactions, luckily versions of MySQL from 5.6 onwards provide some very insightful instrumentation.
Here we will use the information_schema coupled with the …
[Read more]A few days ago I wrote about MySQL performance implications of InnoDB isolation modes and I touched briefly upon the bizarre performance regression I found with InnoDB handling a large amount of versions for a single row. Today I wanted to look a bit deeper into the problem, which I also filed as a bug.
First I validated in which conditions the problem happens. It seems to happen only in REPEATABLE-READ isolation mode and only in case there is some hot rows which get many row versions during a benchmark run. For example the problem does NOT happen if I run sysbench with “uniform” distribution.
In terms of concurrent selects it also seems to require some very special conditions – you need to have the connection to let some …
[Read more]There are few easy ticks to see what is stuck inside MySQL instance. All these techniques will not give you whole picture, but might help to find queries that block performance. Let’s start from what exactly doing your MySQL server right now.
Which queries are running now?
This will give you an idea what’s running right now so you can find long running queries which slowing down MySQL and/or causing replication lag:
mysql -e "SHOW PROCESSLIST" | grep -v -i "sleep"
It is more convenient than just run “SHOW PROCESSLIST” as it’s hiding all connected threads in “Sleep” state so you’ll get a clean output. Also you can get same output but updating each second:
watch -n1 'mysql -e "SHOW FULL PROCESSLIST" | grep -v -i "Sleep"'
What to look for? This is complex output but you can start with Time and State columns. When you see a query running for more …
[Read more]
