Myriad Group Connects Mobile Users Worldwide to Online Services with MySQL Cluster

Although smartphone penetration and 3G/4G coverage is increasing, the cost of data access is still beyond most people’s reach in emerging markets. The GSMA Foundation estimates (i) that only one-fifth of mobile connections in Sub-Saharian Africa are based on 3G, with 4G accounting for less than 1% of the connection... [Read More]

Linux User-Group Console

This post shows you how to add the menu option and GUI to set users and groups. It’s quite a bit easier than mastering all the command-line syntax. It makes setting up the required user and group accounts for an Oracle Enterprise or MySQL database solution much easier.

You add the utility by calling the yum (Yellowdog Updater, Modified) utility like this:

yum installed -y system-config_users

You should see the following:

Loaded plugins: langpacks
Usage:  (more...)

Log Buffer #475: A Carnival of the Vanities for DBAs

This Log Buffer Edition goes through various blogs, and selects some of the top posts from Oracle, SQL Server and MySQL.


MOS Note:136697.1 – New HCHECK.SQL for Oracle Database 12c

ORAchk / EXAchk questions.

Cloud control won’t start!

ASMLib is an optional utility that can be used on Linux systems to manage Oracle ASM devices.

ORA-56841: Master Diskmon cannot connect to a CELL.

Oracle BITAND Function with Examples.


SQL Server:

Natively (more...)

Swedish MySQL user group meet

We are happy to announce the next SMUG (Swedish MySQL User Group) meeting scheduled for May 24th! Please find more detail below: Date: May 24, 2016 Time: 5pm-8pm (+) Place: Emineo, Lilla västerbron 20” in Stockholm, Sweden Proposed agenda: there is scheduled a few talks by the members about... [Read More]

They Scale with MySQL

We sometimes get the question "Will MySQL scale to meet my needs?". Well, consider the following examples: processes 2 billion events/day relying on MySQL. Facebook started out with MySQL, and scaled to 1.6 billion monthly active users. Playing Candy Crush? You’re not the... [Read More]

May 2016 – November 2016 => Events where you can find MySQL

As an update to the blog posted on Mar 15, 2016, please find below list of events where you can find either MySQL Community team or MySQL experts at.  Please find more details at each conference below.  New events are marked with NEW! Any update to already announced event is marked as UPDATE!: ... [Read More]

Thank You for Attending the MySQL Innovation Day

The MySQL Innovation Day took place on Monday, April 25, at the Oracle Conference Center in Redwood Shores, California. Jam-packed with 9 sessions delivered by Oracle's MySQL team, the event offered great opportunity for the attendees to learn the latest products and features in MySQL 5.7, including replication,...... [Read More]

Change Listening Port of MySQL or MariaDB Server

The MySQL and MariaDB server both use a file called my.cnf for parameters that are used to configure the server. This is where the port number and, if you use it, the local socket can be configured. A local socket is the prefered method of connecting to a database as it removes much of the overhead of creating

Reset The root MYSQL/ MariaDB Password

If you’ve lost or forgotten the root user password on a MySQL or MariaDB server you’ll want to reset it and leave all the other accounts and data intact. Fortunately it’s possible, but you’ll need access to an SSH account hosting the instance and the ability to stop and start the database service. Before going any

Presentation: Making MySQL highly available using Oracle Grid Infrastructure

I published my 2014 presentation “Making MySQL highly available using Oracle Grid Infrastructure” in Slideshare. You can view it here:

Fedora LAMP Steps

I posted earlier in the year how to configure a Fedora instance to test PHP code on a local VM. However, I’ve got a few questions on how to find those posts. Here’s a consolidation with links on those steps:

  1. Go to this blog post and install the httpd and php libraries with the yum installer.
  2. In the same blog post as step 1 (you can put the sample PHP code into the /var/www/html directory (more...)

Wanted: RDBMS superpower summary for app developers

At last night's WWCode Cincinnati panel, I recommended that developers talk to their DBA about what advanced capabilities their RDBMS can offer, so that they don't end up reimplementing functionality in the app that are already available (better and more efficiently) in the database itself. Devs can waste a lot of effort by thinking of databases as dumb, inert data boxes.

I was asked an excellent question: "Where can a dev quickly familiarize herself with (more...)

Couchbase 4.0 and related subjects

I last wrote about Couchbase in November, 2012, around the time of Couchbase 2.0. One of the many new features I mentioned then was secondary indexing. Ravi Mayuram just checked in to tell me about Couchbase 4.0. One of the important new features he mentioned was what I think he said was Couchbase’s “first version” of secondary indexing. Obviously, I’m confused.

Now that you’re duly warned, let me remind you of aspects of (more...)

Confusion and problems with lost+found directory in MySQL/Galera cluster configuration

The lost+found directory is filesystem directory created at root level of mounted drive for ext file systems. It is used by file system check tools (fsck) for file recoveries.

In MySql world it can cause confusion or possible problems with synchronisation in Galera cluster configuration.

Let’s check some examples.

I have MySQL database with datadir=/data in configuration file. I have deleted lost+found directory and restarted MySQL service.

When I list my databases this is result:


Create MySQL Index

Indexes are separate data structures that provide alternate pathways to finding data. They can and do generally speed up the processing of queries and other DML commands, like the INSERT, UPDATE, REPLACE INTO, and DELETE statements. Indexes are also called fast access paths.

In the scope of the InnoDB Database Engine, the MySQL database maintains the integrity of indexes after you create them. The upside of indexes is that they can improve (more...)

Coverting MySQL database character set to UTF8

Recently I was engaged to convert the character set for few MySQL databases from latin1 to UTF8 collation utf8_general_ci. This article describes the approach taken for doing the same.

First I will describe various levels at which we can change the character set and collation and then we will see how to convert existing data in a database to required character set.

Backup your database:

Before even thinking about changing character set for your database, (more...)

Test MySQL on AWS quickly

Using sysbench to performance test AWS RDS MySQL hardware is an easy three step  operation. 

Sysbench creates synthetic tests and they are done on a 1 mil row 'sbtest' table that sysbench creates in the MySQL database you indicate. The test doesn't intrude with your database schema, and it doesn't use your data, so it is quite safe. The test is an OLTP test trying to simulate event operations in the database as it (more...)

MariaDB – Measure Replicaton Lag and Check / Fix Replication Inconsistencies using Percona tools

Percona Toolkit is collection of command-line tools to perform many MySQL tasks like creating backups, finding duplicate indexes, managing replication, etc.

In this post I will talk about how to measure replication lag and check/fix replication inconsistencies with this tools:

I am using environment from previous blog post.
Master-Master replication with MariaDB 10.0.16 database on Debian 7.

Install Percona Toolkit on both nodes:

$ sudo wget

$ (more...)

MariaDB(MySQL) Master-Master Replication

The simplest and probably most common replication method is master-slave replication. Basically, data is replicated from master database to the slave. In case of master database failure you must get the slave database up-to-date before failover and then promote slave to be new master.

Another method is to set up replication in both directions called master-master replication. But you must be aware that this setup brings some potential issues as data changes are happening on (more...)

MySQL Locking

Have you ever wondered if MySQL does Row Level Locking? Or wondered why are you getting the error:

ERROR 1205 (HY000) : Lock wait timeout exceeded; try restarting transaction

You get the error because your allocated time to hold a DML lock in a transaction exceeds the set limit. Usually the default limit to hold a DML row lock, set by innodb_lock_wait_timeout db parameter, is 50 seconds. If your transaction doesn't commit/rollback within 50 seconds (more...)