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My slides of MySQL Meetup Viadeo / LeMUG Paris

I was glad to present how to schedule and monitor mysqldump with ZRM community last week in Paris as part of the MySQL Meetup Viadeo / LeMUG

You can find my slides below, enjoy ! :

MYSQLDUMP & ZRM COMMUNITY (EN) View more presentations from Cédric PEINTRE Thanks to Olivier and all the viadeo team in Paris for this event.
And, of course, thanks to all attendees. We need more events like that in France ! Related Posts :

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Why a new memory engine may change everything ?

I’m sure you are aware that the last Percona server release includes a new improved MEMORY storage engine for MySQL.
This new engine is based on Dynamic Row Format and offers some of great features, specialy for VARCHAR, VARBINARY, TEXT and BLOB fields in MEMORY tables.

But because this new MEMORY engine by Percona has some limitations and because Percona server hasn’t used it for its internal temporary tables yet, I would like to talk about what can be the real benefits to have a brand new MEMORY engine based on Dynamic row format specialy for internal memory tables.

Just remember or discover how MySQL uses …

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Finding tables without primary keys

I was checking a third party server, and I needed to find if there were tables without primary keys. This is important to know, not only because the lack of primary keys affects performance and data accuracy in general, but also because in row-based replication performance can degrade beyond belief when updating tables without primary keys.Anyway, I did not remember off the bat any method to get this information from a server with thousands of tables, and thus I went to find a solution on my own.My first instinct called for using the COLUMNS table from the INFORMATIOn_SCHEMA, and so I came up with this query, where I sum the number of columns that are inside either a PRIMARY or UNIQUE key and filter only the ones where such sum is zero (i.e. no primary or unique keys):

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Did you know optimize table can reset your auto-increment ?

I’ve used the OPTIMIZE command for a long time, in particular for disk space problems.

But I recently had a problem with this command and an auto-incremented table, you can reproduce this problem like that :

Create a table with an auto-incremented column :

mysql> use test
Database changed
mysql> create table test_optimize (id int(8) unsigned NOT NULL AUTO_INCREMENT, PRIMARY KEY (id)) engine=InnoDB;
Query OK, 0 rows affected (1.09 sec)

mysql> insert into test_optimize values (1),(2),(3),(4);
Query OK, 4 rows affected (0.28 sec)
Records: 4  Duplicates: 0  Warnings: 0

mysql> show table status like ‘test_optimize’\G
*************************** 1. row ***************************
Name: …

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Fatal timeout !

There are several parameters to set a timeout on MySQL :

But I would like to focus on wait_timeout (or interactive_timeout depending on how you connect)

This timeout allows MySQL to automatically close a connection in case of non-activity during the time defined by this parameter (default value is 28000 seconds).

The problem I wish to explain here may happen when this timeout is set to a low value (about 10 to 30 seconds).

Indeed, in this case, this timeout may have serious consequences, look at that :
[The wait_timeout parameter is set to 10 seconds in this case]

You are connected through the standard MySQL client and you need to run a delete query (bypass autocommit) :

  • mysql> start transaction;
  • [ You …
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Does mpstat can replace vmstat ?

I prefer to say right now, the answer is no !
However, mpstat can provide a minimum service to show essentials information about your CPU usage :

Show usage for all CPU (every 1s) : mpstat 1

Show usage for CPU number 2 (every 1s) : mpstat -P 2 1

It’s possible to retrieve CPU load (user/sys) and IO waits via a simple interface.
And I like the opportunity to focus on a single CPU. It can be a usefull tool for monitoring and scripting.

But there isn’t any information about the run queue processes and this is the bad news here !

So, let me know if you’ve used this tool, all comments are welcome.

Related Posts :

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Scribd is Hiring (I’m Looking for an Operations Engineer to Join My Team)

Scribd is a top 100 site on the web and one of the largest sites built using Ruby on Rails. As one of the first rails sites to reach scale, we’ve built a lot of infrastructure and solved a lot of challenges to get Scribd to where it is today. We actively try to push the envelope and have contributed substantial work back to the open source community.

Scribd has an agile, startup culture and an unusually close working relationship between engineering and ops. You’ll regularly find cross-over work at Scribd, with ops people writing application-layer code and engineers figuring out operations-level problems. We think we’re able to make that work because of the uniquely talented people we have on the team.

To allow us to keep scaling, we’re now looking to add a strong, experienced operations guru to the …

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Enabling IPv6 Support in nginx

This is going to be a really short post, but for someone it could save an hour of life.

So, you’ve nothing to do and you’ve decided to play around with IPv6 or maybe you’re happened to be an administrator of a web service that needs to support IPv6 connectivity and you need to make your nginx server work nicely with this protocol.

First thing you need to do is to enable IPv6 in nginx by recompiling it with --with-ipv6 configure option and reinstalling it. If you use some pre-built package, check if your nginx already has this key enabled by running nginx -V.

The results should have --with-ipv6 option in configure arguments:

[root@node ~]# nginx …
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Remote replication setup with Gearman and MySQL Sandbox

A few months ago, Brian Aker invited me to have a look at Gearman, saying that I could find interesting combinations with MySQL Proxy. I did not forget, and I kept thinking about interesting ways of using it. The first idea that I managed to apply is not related to Proxy, but to a practical problem that I have been keeping in reserve for years, i.e. installing replication systems from remote, without effort.

After some fiddling around with the alternatives, I convinced myself that Gearman is the way to go. Before I proceed to show what I did, though, perhaps it's useful if I spend a few words about Gearman …

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KDE Konsole Backgrounds and ssh

If you are a GUI-oriented person, you need not read this. But if you are like me, you make heavy use of the console. If you are managing many machines as well as your own Linux workstation, it’s VERY important to know where your console session is.

Too many times in the past I had wanted to bring down my workstation, and would type “shutdown” or “reboot” in the console window, only to find out to my horrors that the console was really a remote session to one of my web servers serving up hundreds of web sites.


Well, that prompted me into developing a solution where I can tell at a glance where I happened to be logged in. This way,  I wouldn’t be in danger of issuing dangerous commands on the wrong server. And if you are working for someone else, it also keeps you from being FIRED!

I use KDE to do my development and …

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