On a recent consulting engagement, the PSCE team were charged with what can be considered a fairly common task of synchronising tables between master and slave in MySQL Replication. On this occasion the  schema contained both foreign key constraints and triggers, this post describes how we avoided the potential problems related to such an operation.

The process to synchronise tables in MySQL is to first identify the differences between tables and then execute queries which bring those tables into a consistent state. The first part of the process can be handled by the pt-table-checksum tool, which steps through the table analysing sets of rows (chunks) and recording a checksum value. Then taking advantage of replication, the same process occurs on each of the slaves and the checksums can then be compared. Once the entire table has been processed, a second tool pt-table-sync can be used …

MariaDB 10.1.2 was recently released, and is available for download here:

https://downloads.mariadb.org/mariadb/10.1.2/

This is the third alpha release of MariaDB 10.1, so there are still a lot of new changes, functionalities added, defaults changed, and many bugs fixed (I counted 117, which is *way* down from the 637 fixed in 10.1.1). Since it’s alpha, I’ll only cover the major changes and additions, and omit covering general bug fixes (feel free to browse them all here).

To me, these are the highlights of the new features:

• –mysql56-temporal-format option to use the MySQL-5.6 low level formats to store …

MariaDB 10.0.15 was recently released, and is available for download here:

https://downloads.mariadb.org/mariadb/10.0.15/

This is the sixth GA release of MariaDB 10.0, and 16th overall release of MariaDB 10.0.

This release has an important InnoDB/XtraDB fix, a new addition, security enhancements (and improvement) – all related to yaSSL, so be sure to check out these fixes if you’re running MariaDB 10.0, and not up to 10.0.15 yet. (MariaDB 10.0 is the current stable series of MariaDB. It is an evolution of the MariaDB 5.5 with several entirely new features not found anywhere else and with backported and reimplemented features from MySQL 5.6.)

Here are the main items of note:

1. This release fixes a serious bug in InnoDB and XtraDB that sometimes could cause a hard lock up of the server ( …

In my recent travels, I’ve been speaking with database users at various meetups and trade shows worldwide. Very often, I got questions centering around the best use cases for our products, be it TokuDB, our MySQL storage engine, or, TokuMX, our distribution of MongoDB. Over 90% of the time, I responded Cloud, Big Data or both. You see, in the software industry we’re like kindergartners, we like things to fit into neat categories. If you know any software sales people, you’ll recognize this as a fitting analogy (at least in terms of energy and attention span), but I digress. This strategy helps allocate resources where they are most likely to make an impact, and, thus, optimize our return on investment. In this blog series, I’m going to go slightly against the grain and explain why the Fractal Tree makes databases work in these environments.

Before I get into more detail, let me …

New version of JSON UDF functions has been just released. This is maintenance release which only contains fix for 4 bugs:

74090/19821398 `INSTALL_JSONUDFS` ISSUES A WARNING DUE TO TRUNCATION OF `VERSION_COMPILE_OS`
74091/19692634 `JSON_DEEP_MERGE`: DEEP CRASH IN `MERGE_TREE`
74092/19692628 CRASH WITH SECOND-HAND NULL IN PARAMETERS
74097/19693198 `CREATE_NEW_VALUE`: STACK BUFFER OVERFLOW, %LLD CAN'T FIT IN CHAR[20]

Also 0.3 branch becomes stable branch and no new features will be pushed to this branch in future. Previous stable branch (0.2) removed from MySQL Labs website.

…

In the MySQL Labs version of MySQL version 5.7, there is a new HTTP plugin. The HTTP plugin documentation from the labs site provides this information (from MySQL Labs):

The HTTP Plugin for MySQL adds HTTP(S) interfaces to MySQL. Clients can use the HTTP respectively HTTPS (SSL) protocol to query data stored in MySQL. The query language is SQL but other, simpler interfaces exist. All data is serialized as JSON. This version of MySQL Server HTTP Plugin is a Labs release, which means it’s at an early development stage. It contains several known bugs and limitation, and is meant primarily to give you a rough idea how this plugin will look some day. Likewise, the user API is anything but finalized. Be aware it will change in many respects.

In …

My dear colleagues,  Liz van Dijk, Dimitri Vanoverbeke, Kenny Gryp, also known as the “Party Team” are organizing the “Fosdem MySQL & Friends Devroom Community Dinner” !

Like last year, we’ll be renting a private space to allow for easy socializing. However, in light of this year’s 20th Anniversary of MySQL in May, as well as MariaDB’s 5th Anniversary in February, we want to take things to the next level, and give the night a true community feel. Our new location is available to us until 2AM, and is part of the ICAB buildings, closer to the ULB (more detailed directions on the eventbrite page).

As such, prepare for an evening of food prepared for the Community, by the Community. That’s right, your hosts will be firing up the pizza …

The other day a customer asked me to do capacity planning for their web server farm. I was looking at the CPU graph for one of the web servers that had Hyper-threading switched ON and thought to myself: “This must be quite a misleading graph – it shows 30% CPU usage. It can’t really be that this server can handle 3 times more work?”

Or can it?

I decided to do what we usually do in such case – I decided to test it and find out the truth. Turns out – there’s more to it than meets the eye.

How Intel Hyper-Threading works

Before we get to my benchmark results, let’s talk a little bit about hyper-threading. According to Intel, Intel® Hyper-Threading Technology (Intel® HT Technology) uses processor resources more …

Over the past few months I’ve written a couple of posts about dangerous debt of InnoDB Transactional History and about the fact MVCC can be the cause of severe MySQL performance issues. In this post I will cover a related topic – InnoDB Transaction Isolation Modes, their relationship with MVCC (multi-version concurrency control) and how they impact MySQL performance.

The MySQL Manual provides a decent description of transaction isolation modes supported by MySQL – I will not repeat it here but rather focus on performance implications.

SERIALIZABLE – This is the strongest …

The devroom’s schedule is now published on Fosdem’s website.

As you can see, it will be a heavy day full of good content. You can also notice that there won’t be any lunch-time break.

We advise you to then bring your lunch (like a sandwich) with you in the room and eat it between talks or prepare in advance when you will take your break during a talk you don’t want to attend (is it even possible ?).