I had been involved with subquery optimizations fairly closely, but last week I was surprised to find out that MySQL 5.6 does not support derived table merging. This feature was among the subquery features in the abandoned MySQL 6.0. In MariaDB, it was finished and released as part of MariaDB 5.3/5.5. As for MySQL, neither MySQL 5.6, nor MySQL 5.7 has this feature.

So what is this “derived merge”? It’s simple to understand. When one writes complex queries, it is common to use FROM-clause subqueries as a way to structure the query:

select
  sum(o_totalprice)
from
  (select * from orders where o_orderpriority=’1-URGENT’) as high_prio_orders
where
  o_orderdate between ‘1995-01-01′ and ‘1995-01-07′

MySQL …

1. Backup script

#!/bin/sh
# Fri Jun 27 10:44:49 2014
# done by dragkh
# usage: 
# cat /etc/cron.d/backupmysql 
# 0  3  *  *  *       root    /root/bin/clean.backup.hyperion.mysql.mydumper.daily.sh >>  /var/log/clean.backup.${HOSTNAME}.mysql.mydumper.daily.log 2>&1
# 35  3  *  *  *       root    /root/bin/backup.hyperion.mysql.mydumper.daily.sh >> /var/log/backup.${HOSTNAME}.mysql.mydumper.daily.log 2>&1

ROOT_BACKUP_DIR="/home/mydumper"

seik_date () {
if [ -z $1 ]
then
# cdate=`date +%Y-%m-%d\ %H:%M:%S\ %Z`; export cdate; echo $cdate
cdate=`date -R`; export cdate; echo $cdate
else

if [ -z ${2} ]
then
cdate=`date +%Y-%m-%d.%H.%M.%S`; export cdate; echo $cdate
else
cdate=`date "+%Y-%m-%d %H:%M:%S"`; export cdate; echo $cdate
fi

fi
}


function check_dir {
 test ! -d "${1}" && mkdir -p "${1}"
}


function set_cpu_threads {
    # set the threads one less than the existing 
    threads=$(cat /proc/cpuinfo  |  grep processor | tail -1 | awk …

MySQL Utilities are a set of tools provided by Oracle to perform many kinds of administrative tasks. When GTID-replication is enabled, 2 tools can be used for slave promotion: mysqlrpladmin and mysqlfailover. We will review mysqlrpladmin (version 1.4.3) in this post.

Summary

• mysqlrpladmin can perform manual failover/switchover when GTID-replication is enabled.
• You need to have your servers configured with --master-info-repository = TABLE or to add the --rpl-user option for the tool to work properly.
• The check for errant transactions is …

What is GTID? 

4c2ad77f-697e-11e3-b2c3-c80aa9f17dc4

• This is the server’s 128 bit identification number (SERVER_UUID). It identifies where the transaction was originated. Every server has its own SERVER_UUID.

What problems GTID solves?

• It is possible to identify a transaction uniquely across the replication servers. Make the automation of failover process much easier. There is no need to do calculations, inspect the binary log and so on. Just MASTER_AUTO_POSITION=1.
• At application level, it is easier to do WRITE/READ split. After a write on the MASTER, you have a GTID so just check if that GTID has been executed on the SLAVE that you use for reads.
• Development of new automation tools isn’t a pain now.

How can I implement it?

Three variables are needed in ALL servers of the …

In this blog post regarding MySQL for Excel features included since version 1.2.0, we are going to talk about a new option that is used along with Edit MySQLData operations; very useful when editing data in a multi-user environment. If you are not familiar with editing MySQL data it is very advisable that you visit our thorough blog post about that topic: How To - Guide to editing MySQL data within Excel.

Remember you can install the latest GA or maintenance version using the MySQL Installer or optionally you can download directly any GA or non-GA version from the MySQL Developer Zone. …

Here are a few videos those of you who are just getting started with Sphinx may find useful. The first video demonstrates a very simple implementation with Ubuntu, PHP, and MySQL. The second video is also about installing on Ubuntu. And, the last video discusses fulltext query syntax. Check ‘em out. Quick Start with Ubuntu [...]

My previous post was an introduction to the TokuDB storage engine and aimed at explaining the basics of its design and how it differentiates from InnoDB/XtraDB. This post is all about motivating you to give it a try and have a look for yourself. Percona Server is not officially supporting TokuDB as of today, though the guys in the development team are working hard on this and the first GA release of Percona Server with TokuDB is looming on the horizon. However, there’s a beta version available now. For the installation tests in this post I’ve used the latest version of …

MySQL User Camp Bangalore organized on 20th June, 2014 started as per plan. It was a good gathering. We got many users from different companies like Flipkart, CTS, CGI, Yahoo, Onze Technologies, Webyog and few other startups. Apart from this we also got 2 Mysql customers this time from UID Aadhar project managed by HCL.

Event started on its scheduled time with a welcome speech by Srinivasarao Ravuri, (Senior Manager, Software Development at MySQL India) . He thanked all the attendees for coming followed by a brief agenda and handed over the mic to the speakers for presentation.

It was followed by a talk on ” MySQL 5.7 New Features and NoSQL support in MySQL” by Sudipto Sahoo (Senior Engineer at MySQL India). He gave a good summary on the new features …

On 19th June 2014, Mats Kindahl and I presented a free webinar on why and how you should be using MySQL Fabric to add Sharding (scaling out reads & writes) and High Availability to MySQL. The webinar replay is available here. This blog post includes a transcript of the questions raised during the live webinar together with the responses given – if you’re questions aren’t answered already then please feel free to post them as comments here.

Abstract

MySQL Fabric is built around an extensible and open source framework for managing farms of MySQL Servers. Currently two features have been implemented – High Availability (built on top of MySQL Replication) and …

So I came across an odd situation today.

I have a system that creates memory tables using the PHP  $_COOKIE['PHPSESSID'] value.

Once some work is done it then drops the table.

Two sample tables are below for my example .


@@VERSION: 5.6.19-log
CREATE TABLE `f7a7a8d3a7ba75b5eb1712864c9b27eb` (
    ->   `id` int(11) NOT NULL AUTO_INCREMENT,
    ->   PRIMARY KEY (`id`)
    -> ) ENGINE=MEMORY;

CREATE TABLE `8865e52c7e1bea515e7156f240729275` (
    ->   `id` int(11) NOT NULL AUTO_INCREMENT,
    ->   PRIMARY KEY (`id`)
    -> ) ENGINE=MEMORY;


Now some simple processing occurs on the real tables I used then like I said I dropped them.
…