This post is the second in a series that I will be doing on MySQL Workbench Utilities – Administer MySQL with Python Scripts. You may want to read the first half of this post to understand how MySQL Workbench Utilities work and how you access the scripts. These scripts were written by Chuck Bell (a MySQL (http://mysql.com) employee)

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“Some people even think that “Hadoop” and “Big Data” are synonymous (though this is an over-characterization). Unfortunately, Hadoop was designed based on a paper by Google in 2004 which was focused on use cases involving unstructured data (e.g. extracting words and phrases from Webpages in order to create Google’s Web index). Since it was not [...]

If you’ve ever used non-opensource code, or applications that you don’t have complete control over, then you may have run into situations you need to alter data on a per-row basis but been unable to do so for lack of application SQL access. The solution to this type of problem is to use a MySQL TRIGGER, which allows us to execute arbitrary SQL commands when defined events occur. Why is this useful and how does it work? Well…

For example, I have a freeRADIUS server that uses MySQL as a backend for the user authentication, and one of my server applications (HostBill) provides a freeRADIUS plugin that allows my users to manage their RADIUS accounts; however the default freeRADIUS schema lacks a DATETIME column on the user table. When a user is created (INSERT) or has their password changed (UPDATE)

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MySQL 5.6 adds support for EXPLAIN UPDATE. This is a useful feature, so we want to have it in MariaDB 10.0, too. Besides that, MariaDB 10.0 has SHOW EXPLAIN feature, and we want it work for UPDATE commands, too.

Now, a bit of code history. Why didn’t MySQL have EXPLAIN UPDATE from the start, like other database systems? To the uninformed, lack of EXPLAIN UPDATE looks like simple lazyness. After all, everyone who has read a database textbook can imagine that the code should have this form:

run_update_query(UpdateQuery q) {
   QueryPlan qp= optimize_query(q);
   run_query_plan(qp);
}

and adding EXPLAIN UPDATE is a matter of adding another function:

run_explain_update(UpdateQuery q) {
   QueryPlan qp= optimize_query(q);
   print_update_query_plan(qp);
}

print_update_query_plan(QueryPlan qp)
{
  //

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One of the optimizations we have introduced in MariaDB 5.5 is Extended keys. The idea behind it is rather simple. Inside InnoDB, every secondary index has an invisible suffix of primary key columns. That is, when you create an index:

ALTER TABLE innodb_tbl ADD INDEX (column1, column2);

you’re actually creating this

ALTER TABLE innodb_tbl ADD INDEX (column1, column2, primary_key_column1, …, primary_key_columnN);

The index is extended with primary key columns. SHOW KEYS does not show these extra key parts, but they are there.

Traditionally, MySQL optimizer was half-aware of these extra columns. It knew that doing an index-only scan on InnoDB’s secondary key would read the primary key columns also, and used this property. On the other hand, the optimizer was not able to use the

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To rename a table in MySQL you just need to run a command named RENAME TABLE, the syntax is very easy to use,

RENAME TABLE tb1 TO tb2;

The RENAME TABLE command will rename the table atomically, which means your table will be locked during the command.
You can also rename more than one table in one command:

RENAME TABLE tb1 TO tb2, tb3 TO tb4;

To rename the table you will need ALTER and DROP privileges on the old table and CREATE and INSERT on the new one.

You just need to be careful if you use triggers, on the bellow example, after a INSERT on table Cities, I count +1 to NOfCities on the iserted Countries, what happens if I rename the table Contries?

mysql> SHOW TRIGGERS\G
*************************** 1. row ***************************
             Trigger: PlusOneCities

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In my previous post, I shared my finding that MySQL 5.6.7 does not make a cost-based choice between Materialization and IN-to-EXISTS strategies for subqueries.

It turns out I was wrong. As Guilhem Bichot has blogged here, he has implemented cost-based choice between Materialization and IN->EXISTS in MySQL 5.6.7. Igor Babaev also wrote about the topic, and covered the reasons I didn’t see the feature - it isn’t mentioned in the documentation, development process at Oracle is quite closed, and the feature didn’t work for a basic example that I have tried.

Let’s try to focus on the technical part of it. Looking at the source code, I see that

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MySQL IN??? MySQL OR??? MySQL AND???
When I use one and when I use other?

we will use the city table to this tutorial:

+-------------+----------+------+-----+---------+----------------+
| Field       | Type     | Null | Key | Default | Extra          |
+-------------+----------+------+-----+---------+----------------+
| ID          | int(11)  | NO   | PRI | NULL    | auto_increment |
| Name        | char(35) | NO   |     |         |                |
| CountryCode | char(3)  | NO   | MUL |         |                |
| District    | char(20) | NO   |     |         |                |
| Population  | int(11)  | NO   |     | 0       |                |
+-------------+----------+------+-----+---------+----------------+

Let’s see a simple rule to clarify this:

AND – we use AND to add a new condition which will need to be

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Two cons against NoSQL data stores read like this: 1. It’s very hard to move data out from one NoSQL to some other system, even other NoSQL. There is a very hard lock in when it comes to NoSQL. If you ever have to move to another database, you have basically to re-implement a lot [...]

Hi guys, today let’s learn about a very useful option on mysql command line to recording all what happen in your mysql session, It’s the option –tee. Is very easy to use, you just need to add the –tee=/path/to/file

mysql -u root -p --tee=/tmp/log.mysql

It is all for today!
Enjoy!!!

“For analytical things, eventual consistency is ok (as long as you can know after you have run them if they were consistent or not). For real world involving money or resources it’s not necessarily the case.” — Michael “Monty” Widenius. In a recent interview, I asked Justin Sheehy, Chief Technology Officer at Basho Technologies, maker [...]

“For analytical things, eventual consistency is ok (as long as you can know after you have run them if they were consistent or not). For real world involving money or resources it’s not necessarily the case.” — Michael “Monty” Widenius. In a recent interview, I asked Justin Sheehy, Chief Technology Officer at Basho Technologies, maker [...]

MySQL 5.6 is now RC, I suppose this means that all features that were intended to be in release are pushed, so it’s time to take a look and see what’s going to be in MySQL 5.6 GA.

I decided to look at subquery optimizations and compare them to what we’ve got in MariaDB 5.3/5.5. In case you don’t know, subquery optimizations in MySQL 5.6 and MariaDB come from a common ancestor - MySQL 6.0 alpha, which was released in spring 2009 and then abandoned because there were too many unstable features pushed into it.

Then, both MariaDB team and Oracle salvaged subquery code out of the 6.0 mess, and worked to get it in shape for release. MariaDB released its results in GA quality in April 2012 as MariaDB 5.3, which was quickly followed by MariaDB 5.5.

Inside

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“While I believe that one size fits most, claims that RDBMS can no longer keep up with modern workloads come in from all directions. When people talk about performance of databases on large systems, the root cause of their concerns is often the performance of the underlying B-tree index”– Martín Farach-Colton. Scaling MySQL and MariaDB [...]

Tuesday, September 25, 2012

MySQL and PHP are two key components in the open-source LAMP stack, and are widely used by web developers. One day you launched a website, and it gradually gained traction and now serves hundreds times more traffic than day one. As a PHP developer, have you ever looked back and adjusted the MySQL configurations accordingly to meet the most current website load? Have you ever wondered if there are secret tips you might have missed or common mistakes that you could have avoided but never thought of? If you answered yes to either question, this presentation is for you!

In this live webinar, PHP & MySQL experts Ulf Wendel and Johannes Schlüter will share the top 10 tips and mistakes for PHP developers. After a quick overview of lesser known but cool client and server features and plugins, and a recap

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ConFoo is one of the most important web developer-oriented conferences. ConFoo 2013 will be held on February 25 through March 1 in Montreal, Canada.

We just opened call for papers and we are looking for the best PHP, Java, Ruby, DotNet,HTML5 experts who are willing to share their knowledge with the Canadian community. Candidates can submit proposals until September 23. Consult the call for papers page for details and to start submitting. That page also explains what expenses ConFoo can cover for speakers. You can also get advice on how to write proposals.

The call for papers is public, meaning that all proposals get published on the website for others to

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Over the next few months, I am going to be writing about the MySQL Utilities, and I will be posting links to each individual blog on this page.

If you haven’t heard of the MySQL Utilities (from the introduction to MySQL Utilities page):

“MySQL Utilities is a package of utilities that are used for maintenance and administration of MySQL servers. These utilities encapsulate a set of primitive commands, and bundles them so they can be used to perform macro operations with a single command. MySQL Utilities may be installed via MySQL Workbench, or as a standalone package. The utilities are written in

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