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10 Newer Entries Showing entries 91 to 100 of 1147 10 Older Entries

Displaying posts with tag: Databases (reset)

On operating system upgrades and a packager’s nightmare
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A fairy tale

Once upon a time I did an operating system upgrade, a minor one that should do no harm, but just get me up to date by fixing any bugs in the version I had been using. It seemed like a good idea.

All seemed to be fine. I use a package provided by an external vendor and not the one produced by the operating system provider as this vendor provides a newer version of the package and I need that. The vendor has to make his package fit in the os environment his package is built for and normally does a pretty good job.

I use automation to build my systems and when I built a new one some issues appeared. Related to the new version of the OS the provider had enhanced one of his packages and the installation pulled in new dependencies. The install of the external package I use then broke as it conflicted with the new dependency

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2013 SkySQL and MariaDB Solutions Videos Are Online!
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I do not recall seeing an announcement about it, but I went looking for the videos today and lo and behold, they were up! Forgive me if I missed a post about it….but if you also missed it, here they are:

2013 SkySQL and MariaDB Solutions Day for the MySQL Database videos

Madrid MySQL Users Group worth creating?
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I’m interested in meeting up and sharing experiences about using MySQL and managing MySQL servers with people here locally in Madrid. I had a quick look around and could see no MySQL user groups locally, so it might be nice to create such a group and exchange ideas over a beer, coffee or cola every once in a while. If you’re in Madrid and are interested please let me know. I’ve created a temporary  email address: madrid-mysql-users-2013 AT wl0.org (careful with the domain), which you can contact me on to confirm an interest.  Oh and I’d expect these meet ups to be in Spanish, but that’s not a requirement.

Estoy interesado en reunirme y compartir experiencias sobre el uso de MySQL y administración de servidores de MySQL con la gente aquí en Madrid. He echado un vistazo en Internet y no he visto ningún grupo de usuarios de MySQL a nivel

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MySQL Quirk with Not Null Columns and Default Values
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One of my coworkers came across a strange quirk in MySQL with default values for not null columns. Take a look at this table:

Create Table Posts
(
     PostID Int Auto_Increment Primary Key
    ,Title Varchar(30) Not Null
    ,Body Text Not Null
    ,Summary Varchar(25) Not Null Default ''
);

Note the column Summary that is marked not null but has a default value of an empty string. Now, try to insert a null value into this column.

Insert Into Posts (Title, Body, Summary) Values ('A title', 'A body', null);

You’ll get this error:

ERROR 1048 (23000): Column 'Summary' cannot be null

Now, using an extended insert (where you specify multiple rows in an insert statement), we can insert the same data and it will complete successfully,

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A Different Spin On the max_allowed_packet Problem
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Back in November, I filed MySQL bug 67448, talking about a different type of max_allowed_packet problem.

See, an application had put data into the database, but could not retrieve it without getting max_allowed_packet. With the help of some really smart community folks (named Jesper Hansen, Brandon Johnson and Shane Bester), we determined that MySQL actually has 2 different max_allowed_packet settings: client and server.

When you change the max_allowed_packet variable, you are changing the server variable if it is in [mysqld] and the client variable if it is in [client] or [mysql] or whatever client you have. As far as we can tell, there’s no way to actually view what the client variable is, as looking at both the session and global max_allowed_packet variable shows you the server

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ulimits and upgrading from Oracle MySQL 5.0 to Percona patched MySQL 5.1
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After upgrading to Percona’s patched MySQL 5.1*, end users were having connectivity problems, and reporting errors such as:

OperationalError: (2003, "Can't connect to MySQL server on 'db-amo-ro' (110)")

TimeoutError: Request timed out after 5.000000 seconds

OperationalError: (1135, "Can't create a new thread (errno 11); if you are not out of available memory, you can consult the manual for a possible OS-dependent bug")

We had these same problems a while back, before increasing ulimit settings in /etc/sysconfig/mysqld. Oracle’s MySQL startup script specifically sources this file:

[ -e /etc/sysconfig/$prog ] && . /etc/sysconfig/$prog

However, we saw these errors again when we upgraded to Percona’s MySQL 5.1.

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MySQL User Group Video – Determinism and Databases
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The May Boston MySQL User Group featured John Hugg of VoltDB talking about determinism and databases. I have uploaded the hour-long video to http://www.youtube.com/watch?v=mTDLyRauJtw. Seasoned MySQLers will nod their heads because the problems described are familiar, and those who are not exactly sure what “determinism and databases” means will learn a lot.

Enjoy!

(As always, videos are free on YouTube with no login or attempt to solicit your e-mail address or any other information)

Upgrading support.mozilla.org databases
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A while ago (November 2012 to be exact), we upgraded the support.mozilla.org databases from Percona 5.1 to MariaDB 5.5 (the next step, happening soon, is upgrading them to Oracle’s MySQL 5.6). One of the engineers and I had a conversation where he mentioned that “one of our worst performing views on SUMO is doing waaaayyy better with the upgraded databases”, that it “seems more stable” and that “I stopped receiving ‘MySQL went away or disconnected emails’ which came in once in a while.”

It’s always nice to see upgrades actually making a difference. In our case we saw a lot less CPU wait, though that might also be partially due to tuning the memory settings on the machines and adding in another read slave to handle queries. As a result, network traffic throughput went from less than 1 Mb/sec to about 18

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Percona Ireland??
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Anybody else noticed that Percona appears to not be a US entity any more?

I observed it today.

$ sudo /usr/bin/innobackupex ...
InnoDB Backup Utility v1.5.1-xtrabackup; Copyright 2003, 2009 Innobase Oy
and Percona Ireland Ltd 2009-2012.  All Rights Reserved.

This software is published under
the GNU GENERAL PUBLIC LICENSE Version 2, June 1991.

In previous versions this did say Percona Inc, 2009-2012.

The footer of the Documentation also states © Copyright Percona Ireland Ltd. 2009-2013.

Women in Science and Engineering (WISE) Computing Skills Boot Camp
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Software Carpentry is running a 2-day software skills boot camp in Boston, June 24-25th 2013, for women in science, engineering, medicine, and related research
areas. Registration is $20.

Boot camps alternate short tutorials with hands-on practical exercises. You are taught tools and concepts you can use immediately to increase your productivity and improve confidence in your results. Topics covered include the Unix shell, version control, basic Python programming, testing, and debugging — the core skills needed to write, test and manage research software.

This boot camp is open to women at all stages of their research careers, from graduate students, post-docs, and faculty to staff scientists


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10 Newer Entries Showing entries 91 to 100 of 1147 10 Older Entries

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