Section 6: "Profile a real case" 6.1 INTRODUCTION

Profiling & Debugging is an argument that would require an entire book, the aim of this(and the others) posts of this series is to give you the basic knowledge on how to work with these tools and techniques withing Eclipse. For instance if you want to learn to profile with OProfile you should study on the abundant and separate resources, you may start from: http://OProfile.sourceforge.net

6.2 ABOUT NAMING THE PROJECT

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Last week, yours truly has pushed a new feature into MariaDB 10.1 tree: ANALYZE statement.

The idea of this feature is to make it easy to compare query plan with query execution. ANALYZE statement will run the statement, and produce EXPLAIN-like output, where optimizer’s estimates are followed by numbers that were observed when running the query. The output looks like this:

Here,

• Next to rows there is r_rows column which shows how many records were read from the table.
• Next to filtered there is r_filtered column which shows which fraction of records was left after the part of the WHERE condition attached to the table was checked.

I think this should explain the feature. If you want more details, please refer to the KB article …

On July 16 I’ll be presenting my next webinar focusing on common mistakes committed by MySQL users.

How to Avoid Even More of the Common (but Deadly) MySQL Development Mistakes

“Why can’t I just save my data to a file?”

Using an SQL database seems so complex to get right, and for good reason. The variety of data-driven applications is practically limitless, and as project requirements change, we find ourselves taking shortcuts and adopting bad habits. But there are proven methods to understanding how to develop and manage data in a scalable and reliable way. This talk shows you some of these methods, including:

• How to optimize a database application with partitioning and sharding.
• How to avoid the secret security …

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 …