I love finding out new things about MySQL. Last week, I stumbled on a query that had the phrase “SOUNDS LIKE” in it. Sounds made-up, right? Turns out MySQL is using a known “soundex” algorithm common to most databases, and popular in use cases in geneaology.

The basic idea is that words are encoded according to their consonants. Consonants that sound similar (like M and N) are given the same code. Here’s a simple example:

(“soundex” and “sounds like” are different ways of doing the same thing in these queries)

MariaDB> select soundex("boom");
+-----------------+
| soundex("boom") |
+-----------------+
| B500            |
+-----------------+

MariaDB> select soundex("bam");
+----------------+
| soundex("bam") |
+----------------+
| B500           |
+----------------+

MariaDB> select soundex("bin");
+----------------+
| soundex("bin") |
+----------------+
| B500           |
+----------------+

…

One of our Percona Support customers recently reported that Percona XtraBackup failed with a page corruption error on an InnoDB table. The customer thought it was a problem or bug in the Percona XtraBackup tool. After investigation we found that an InnoDB page was actually corrupted and a Percona XtraBackup tool caught the error as expected and hence the backup job failed.

I thought this would be an interesting topic and worthy of a blog post. In this article I will describe the innochecksum tool, when and how to use it and what are the possible fixes if an InnoDB table suffers from …

On March 10, 2015, we released MySQL-5.7.6 and among many other things it includes multi-source replication which …

One of my customers wants to search for names in a table. But sometimes the search is case insensitive, next time search should be done case sensitive. The index on that column always is created with the collation of the column. And if you search with a different collation in mind, you end up with a full table scan. Here is an example:

The problem

 mysql> SHOW CREATE TABLE City\G  
 *************************** 1. row ***************************  
 Table: City  
 Create Table: CREATE TABLE `City` (  
 `ID` int(11) NOT NULL AUTO_INCREMENT,  
 `Name` char(35) CHARACTER SET utf8 COLLATE utf8_bin DEFAULT NULL,  
 `CountryCode` char(3) NOT NULL DEFAULT '',  
 `District` char(20) NOT NULL DEFAULT '',  
 `Population` int(11) NOT NULL DEFAULT '0',  
 PRIMARY KEY (`ID`),  
 KEY `CountryCode` (`CountryCode`),  
 KEY `Name` (`Name`),  
 ) ENGINE=InnoDB AUTO_INCREMENT=4080 DEFAULT CHARSET=latin1  
 1 row in set (0,00 sec)  

…

My webinar “Multi-threaded Replication in MySQL 5.6 and 5.7″ on February 25 generated several excellent questions following the presentation (available here for playback along with the slides). I didn’t have time to answer many of the questions during the session and so in this post I answer all of them. Thanks to everyone who attended!

Q: What do you expect from MTS with logical clock? Do you think performance would be good as with per database?
A: MTS with 5.6 is not usable if you have a single database. I do not have numbers, but this is quite frequent. With 5.7 everyone should be able to benefit from multi-threaded replication.

Q: When MySQL 5.6 was released, performance of MTS was lower, than in 5.5, for example. Is this addressed now?
A: I am not sure which …

The MySQL developer tools team is pleased to announce 6.3.2 RC - the first release candidate for MySQL Workbench 6.3

For the full list of changes in this revision, visit

http://dev.mysql.com/doc/relnotes/workbench/en/changes-6-3.html

For detailed information about the new features, see What’s
New in MySQL Workbench 6.3
http://dev.mysql.com/doc/workbench/en/wb-what-is-new-63.html

For discussion, join the MySQL Workbench Forums:
http://forums.mysql.com/index.php?151

Download MySQL Workbench 6.3.2 RC now, for Windows, Mac OS X 10.7+,
Oracle Linux 6 and 7, Fedora 20 and Fedora 21, Ubuntu 14.04 and …

MySQL 5.7.6 brings in a simplification that solves the very first problem that I encountered back in the days when I first started using MySQL 5.0. Namely…

How do I create a new database instance?

I know it sounds like a very basic question. But as it turned out, the answer was not that simple. I tried mysqld --help. Nothing there. And then, after reading the manual and trying out the complex command line (including redirection) based steps a couple of times, I just resorted to employing the mysql-test-run.pl test suite driver to create the initial system tables and data for me.

Obviously this has …

I’ve been working on MySQL since 2008 but I didn’t write any technical blogs until I joined FromDual GmbH and my first blog was published in October 24th 2013! (You can find all my blogs at FromDual here).
I liked writing blogs for many reasons but mainly for the following two:

1. Sharing knowledge and contributing with MySQL community to make the information easier and available for all.
2. Very good reference for myself to do my daily work more efficiently.

Now, I’m eager to blog again so I decided to create my own blog, MySQL Step-by-Step Blog.
The idea of choosing the name “Step-by-Step” is I like to explain all steps needed for doing a task – you may have discovered that …

The MariaDB CONNECT storage engine now offers access to JSON file and allows you to see a external JSON file as a MariaDB table. JSON (JavaScript Object Notation) is a lightweight data-interchange format widely used on the Internet. JSON like XML represents data hierarchically. The mapping from hierarchical data to tabular data needs to be specified.

[...]

I am leaving Oracle. My last day will be tomorrow. Since Oracle blogs are for Oracle employees only I would not be able to post here. I will write new posts to my personal just created blog http://troubleshootingfreak.blogspot.com/

This blog will stay, so you should be able to access older entries. Therefore I would not migrate them. Just don't expect somebody will manage comments. If you have questions about old entries in this blog use this page.

Last years I worked on JSON UDF project. I will stop working on it after I leave to avoid conflict of interest with Oracle, but project will live. I don't know if it will be passive or Oracle will find new developer for it, but versions 0.3.3 and …