Kalasha,
You might need to execute the SQL statement (FLUSH LOGS;) and then check the log files.

Hi Przemek,

I do agree with you that the replication will be blocked until the slaves finish executing the alter statement, but the table being changed on the slaves themselves wont be blocked during the alter statement the same like the master. I agree also that this could be considered as an advantage of pt-online-schema-change over Online DDL. I’ll add that to the blog. Thanks Przemek for the hint …

We are very satisfied with the functionality and the launch. The entire Cluster is running absolutely stable. This is a significant advantage for our customers because we are able to offer our services without interruption. We will use Galera in further projects and convert our existing Master/Slave installations.

A. Rempening, Datenbank-Administrator, KiKxxl GmbH

Download this case study: KiKxxl Gmbh: Highly available communication services based on a MySQL database and Galera Cluster (PDF, 420 kbyte).

Hi Shlomi

Can you please explain more on how did you produce your results?
Because Online DDL are DDL statements anyway and will be written to the binary log as statements (even if RBR is being used) which means that it will be executed on the slave the same like it was on the master.

By the way, I've tested it in a replication environment and the table being changed on the slave was not blocked during the statement execution and it took approximately the same or even less time than it was on the master. …

One of the most expensive database operations is performing Data Definition Language (DDL, e.g. CREATE, DROP, ALTER, etc.) statements, specially, the ALTER statements because MySQL blocks the entire table for both reads and writes while modifying the table.

For the huge tables, this might take hours to get the table changed which affects the application, so that, a good planning is required for such operations in order to avoid doing these changes during the peak times. For those people who have 24/7 …

The FromDual Ops Center for MariaDB and MySQL (focmm) is a browser-based Graphical User Interface (GUI) to operate and manage your MariaDB and MySQL database farms (2 - 99 instances) more easily.
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Hello,

there are companies which earn tens of thousands of Euros per hour with their MySQL databases. Other companies operate their ERP system on MySQL, to which 1000 employees are attached to. Is the database down 1000 people are not working any more until the system is working again! Downtime costs starting at EUR 30'000.- per hour upwards.

Support through the MySQL specialists?

These companies have properly planned operations of their MySQL databases, designed their production systems redundantly and …

Thanks, Morgan!

MySQL single query performance - the truth!

As suggested by morgo I did a little test for the same query and the same data-set mentioned in Impact of column types on MySQL JOIN performance but looking into an other dimension: the time (aka MySQL versions).

The answer

To make it short. As a good consultant the answer must be: “It depends!” :-)

The test

The query was again the following:

SELECT *
  FROM a
  JOIN b ON b.a_id = a.id
 WHERE a.id BETWEEN 10000 AND 15000
;

The Query Execution Plan was …

Hi Joffrey,

I think NDB tables use 4-byte alignment not InnoDB:

NDB tables use 4-byte alignment; all NDB data storage is done in multiples of 4 bytes. Thus, a column value that would typically take 15 bytes requires 16 bytes in an NDB table. For example, in NDB tables, the TINYINT, SMALLINT, MEDIUMINT, and INTEGER (INT) column types each require 4 bytes storage per record due to the alignment factor.

Check this manual page for reference.

Thanks,
Abdel-Mawla

Hi Morgan,

Thanks!

I have planed such a test already a while ago but did not find the time to do it yet...

In my mind I have some numbers showing that since MySQL 4.0 single query performance has decreased significantly...

This leads to the question: Where are all the MySQL branches and forks heading to and is this in the interest of the majority of the MySQL users or just in the interest of a few ones like Facebook, LinkeId, Google, Booking.com etc...?

Regards,
Oli

In our MySQL trainings and consulting engagements we tell our customers always to use the smallest possible data type to get better query performance. Especially for the JOIN columns. This advice is supported as well by the MySQL documentation in the chapter Optimizing Data Types:

Use the most efficient (smallest) data types possible. MySQL has many specialized types that save disk space and memory. For example, use the smaller integer types if possible to get smaller tables. MEDIUMINT is often a better …

FromDual has the pleasure to announce the release of the new version 1.0.2 of its popular multi-instance MySQL Environment MyEnv.

You can download MyEnv from here.

In the inconceivable case that you find a bug in MyEnv please report it to our Bugtracker.

Any feedback, statements and testimonials are welcome as well! Please send them to feedback@fromdual.com.

If you have questions about MyEnv we will answer them in the MyEnv forum.

Upgrade from 1.0.x to 1.0.2

# cd /home/mysql/product
# tar xf …

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Features

Galera is a synchronous multi-master replication Cluster for MySQL/InnoDB databases, having features like:

• Synchronous replication
• Active-active multi-master topology
• Read and write to any cluster node
• Automatic membership control, failed nodes drop from the cluster
• Automatic node joining
• True parallel replication, on row level
• Direct client connections, native MySQL look & feel

Benefits

The benefits of these features are:

• No slave lag
• No lost transactions
• Read scalability and write …

Hello csmanioto,

As mentioned above this is a PoC and should never be used on system with critical data because it is an evil hack!!!

If you would like to see this comming in production soon you should vote fore this feature request.

Table of Contents

• Introduction
• Prerequisites
• What is MyEnv?
• MySQL Workbench configuration.
  • Add MySQL connections to MySQL Workbench.
  • Start/Stop instance configurations.

Introduction

MySQL Workbench is a very good and free GUI tool provided by Oracle to manage MySQL administration and development tasks. Opening many MySQL connections (same or different instances, remote or local MySQL servers) at the same time is one of its main features. While it’s working fine to perform SQL statements on the …

I just want to mention here that Galera 3.1 GA is now released but the online upgrade from MySQL 5.5 to 5.6 has some problems and a workaround should be made (Bug #1251137) to get this process done.

Hi,

The output you just provided could be gotten by having your database’s tables backed up individually and then restore them the same way.
For this purpose, the backup script should be something like:

#!/bin/bash
cd /backup/script/
for x in `cat tables.txt`
do 
echo $x
mysqldump --user=user_name --password='password' database_name $x  > /backup/$x.sql

echo 'Table '.$x.' completed ...'
done
echo 'Database backed up successfully ...'

Where the tables.txt file contains all tables names …