Thank you for attending the Sun Startup Essentials webinar on
Security for Web Applications, here is a list of useful links to
learn more about and start implementing the different
technologies that were covered during the presentation:
Image by Aranda\Lasch via Flickr
One of my favorite terms at the moment is “Big Data”. While
all terms are by nature subjective, in this post I will try and
explain what Big Data means to me.
So what is Big Data?Big Data is the “modern scale” at which we
are defining or data usage challenges. Big Data begins at
the point where need to seriously start thinking about the
technologies used to drive our information needs.
While Big Data as a term seems to refer to volume this isn’t the
case. Many existing technologies have little problem
physically handling large volumes (TB or PB) of data.
Instead the Big Data challenges result out of the combination of
volume and our usage demands from that data. And those …
From Stack Overflow:
I have a table users and there is a field
invited_by_id showing user id of the person who
invited this user.
I need to make a MySQL query returning rows with
all the fields from users plus a invites_count field
showing how many people were invited by each user.
The task seems very simple (and it is in fact), but there are at least two approaches to do it. It this article, I will discuss the benefits and the drawbacks of each approach.
GROUP BY
The first approach is using GROUP BY:
SELECT u.*, COUNT(ui.id)
FROM users u
LEFT JOIN
users ui
ON ui.invited_by = u.id
GROUP BY
u.id
This is a GROUP BY with a self join, very simple.
There are only two …
A new release with lots of new features and bugfixes. To mention
some of them:
* Completely rewritten, homebrown database communication layer,
supporting Unicode from the very beginning
* Rewritten table editor, now supporting foreign keys and
drag'n drop editing
* Rewritten SQL exporter: Removed useless options, dramatically
improved performance and added support for views, procedures and
triggers
* New feature: Multiple query tabs
* New feature: Create and edit trigger with a new trigger
editor
* More native Windows 7 / Aero style support
* Maintenance dialog rewritten, introducing some new
options
* New feature: Find text on server, search any group of
tables/views for specific text
* …
Do you think that MySQL is only for web applications? Well, think
twice. MySQL is a pure relational database and with all the
features pumped up in 5.0 and 5.1 it can be a perfect data
warehouse machine.
Not convinced? Well, let me help you. Next week, on Thursday 4th
of Feb to be precise, we will host a new breakfast event in
London on this subject. Considering the limited space available
at the venue, the event is by invitation only, but If you are
around London and you are interested, you can drop me an email at
ivan@mysql.com with all your details. If there are still seats
available, I will be glad to grant you a pass. If you can't
participate, don't worry. As usual, we will post slides and
comments on the MySQL site.
During the event we will show you why and how MySQL can be used
in a data warehouse project. I will cover this part. I will also
show a basic cookbook with tips and tricks on how to set up MySQL
in a DW …
I have been upgrading more MySQL database instances recently and have found a few more potential gotchas, which if you are not careful, can potentially be rather nasty. These are not documented explicitly by MySQL, so it may be handy for you to know if you have not come across this type of thing before.
Most of the issues are those related to upgrading MySQL instances which are replicated, either the master servers or the slaves. Some seem specific to the rpm packages I am using (MySQL enterprise or MySQL advanced rpms), though others are not.
Take care upgrading a 5.0 master when you have 5.1 slaves
It is not a good idea to run a mixed major version of mysql in a replicated environment so why would I be doing this? If you work in a replicated environment and have several slaves then it is recommended that you upgrade the slaves first. I work with quite a few slaves so the process of upgrading them all takes longer …
[Read more]One unfortunate side effect of the Oracle acquisition of Sun and therefore MySQL is that apparently a number of good people will no longer be part of that team. If any are reading and need a lead, we have a number of positions open at http://www.messagesystems.com/company/careers/:
…
[Read more]
Recently we had a case where a customer got some corrupted blocks
in his InnoDB tables. His largest tables where quite big, about
30 to 100 Gbyte. Why he got this corrupted blocks we did not find
out yet (disk broken?).
When you have corrupted blocks in InnoDB, it is mandatory to get
rid of them again. Otherwise your database can crash
suddenly.
If you are lucky only "normal" tables are concerned. So you can
dump, drop, recreate and load them again as described in the
InnoDB recovery procedure in the MySQL documentation [1].
If you are not so lucky you have to recreate your complete
database or go back to an old backup and do a restore with a
Point-in-Time-Recovery (PITR).
To find out if some tables are corrupted MySQL provides 2 tools:
The innochecksum utility [2] and the mysqlcheck utility [3] or
you can use the CHECK TABLE command manually (which is used by
mysqlcheck).
I wanted to know …
Recently we had a case where a customer got some corrupted blocks in his InnoDB tables. His largest tables where quite big, about 30 to 100 Gbyte. Why he got this corrupted blocks we did not find out yet (disk broken?).
When you have corrupted blocks in InnoDB, it is mandatory to get
rid of them again. Otherwise your database can crash
suddenly.
If you are lucky only "normal" tables are concerned. So you can
dump, drop, recreate and load them again as described in the
InnoDB recovery procedure in the MySQL documentation [1].
If you are not so lucky you have to recreate your complete
database or go back to an old backup and do a restore with a
Point-in-Time-Recovery (PITR).
To find out if some tables are corrupted MySQL provides 2 tools: The innochecksum utility [2] and the mysqlcheck utility [3] or you can use the CHECK TABLE command manually (which is used by mysqlcheck).
I wanted to know how CHECK TABLE …
[Read more]Recently we had a case where a customer got some corrupted blocks in his InnoDB tables. His largest tables where quite big, about 30 to 100 Gbyte. Why he got this corrupted blocks we did not find out yet (disk broken?).
When you have corrupted blocks in InnoDB, it is mandatory to get
rid of them again. Otherwise your database can crash
suddenly.
If you are lucky only "normal" tables are concerned. So you can
dump, drop, recreate and load them again as described in the
InnoDB recovery procedure in the MySQL documentation [1].
If you are not so lucky you have to recreate your complete
database or go back to an old backup and do a restore with a
Point-in-Time-Recovery (PITR).
To find out if some tables are corrupted MySQL provides 2 tools: The innochecksum utility [2] and the mysqlcheck utility [3] or you can use the CHECK TABLE command manually (which is used by mysqlcheck).
I wanted to know how CHECK TABLE …
[Read more]