I was searching around and was pleasantly surprised when I ran across this new MySQL Troubleshooting book by Sveta Smirnova:

“MySQL Troubleshooting – What To Do When Queries Don’t Work”

http://shop.oreilly.com/product/0636920021964.do

Having worked with Sveta in Support for years, I’m certain this book is chock-full of great troubleshooting techniques and advices (and you can get a good idea from the “Table of Contents” listed on the above page).

I’m always happy to see new MySQL-related books.

Congratulations, Sveta!

Here's a question that was driving me crazy: Why do these two explain plans look different?

explain select a from test order by b;
+----+-------------+-------+-------+---------------+------+---------+------+---------+-------------+
| id | select_type | table | type  | possible_keys | key  | key_len | ref  | rows    | Extra       |
+----+-------------+-------+-------+---------------+------+---------+------+---------+-------------+
|  1 | SIMPLE      | test  | index | NULL          | b    | 5       | NULL | 3263769 | Using index |
+----+-------------+-------+-------+---------------+------+---------+------+---------+-------------+

and this

explain select a,c from test order by b;
+----+-------------+-------+------+---------------+------+---------+------+---------+----------------+
| id |

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I recently came across a dev VM running MySQL 5.0.77 (an old release, 28 January 2009) that didn’t have InnoDB available. skip-innodb wasn’t set, SHOW VARIABLES LIKE '%innodb%' looked as expected, but with one exception: the value of have-innodb was DISABLED.

I confirmed this with SHOW ENGINES:

(root@localhost) [(none)]> show engines;
+------------+----------+----------------------------------------------------------------+
| Engine     | Support  | Comment                                                        |
+------------+----------+----------------------------------------------------------------+
| MyISAM     | DEFAULT  | Default engine as of MySQL 3.23 with great performance

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Similar to my other catch-all pages on Server Variables, Changelogs, and Documentation, I’ve added a new ‘Downloads’ section.

Basically, it’s just a single source containing links to all of your favorite MySQLs and related products, such as MySQL, MariaDB, XtraDB, Xtrabackup, MySQL Proxy, Connectors and more:

http://www.chriscalender.com/?page_id=831

Hope this helps.

 

I'm pleased to announce the release of Spider storage engine version 2.28(beta) and Vertical Partitioning storage engine version 0.17(beta).
Spider is a Storage Engine for database sharding.
http://spiderformysql.com/
Vertical Partitioning is a Storage Engine for vertical partitioning for a table.
http://launchpad.net/vpformysql

Please use the following for downloading binary file.
http://spiderformysql.com/download_spider.html

The main changes in this version are following.
Spider
- Support parallel searching. ("spider_bgs_mode > 0")
The table using the Spider bundled MySQL and table partitioning performs parallel search of each partition. However,











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After the recent update to pt-table-checksum, I’ve seen a few FAQs about it.

Q: is it still multi-threaded/parallel? A: No, that was a pile of bugs and complexity. If you need to run the tool in parallel to take advantage of powerful hardware, you can run several instances, say, one per database.

Q: what chunk size should I use? A: None, let the tool adjust itself dynamically.

Q: what if it skips a table or chunk because it’s oversized? A: this should be rare unless you have tables without any indexes; if you want to do the table in one chunk, run the tool again and specify to checksum only that table, with an appropriately large chunk size. This is one of the rare cases where you will need to specify a chunk size.

Q: what commandline options should I use after upgrading? A: It has sensible defaults for everything, and is designed

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Some administrative tasks can be simplified by using common_schema/QueryScript. I'm collecting a bunch of these for documentation. Here's one for example:

The DBA/developer has the task of retaining only top 3 most populated countries per continent. That is, she has to DELETE 4th, 5th, 6th, ... most populated counties in each continent.

Is it possible to work out with a single query? Yes. But the query is not pretty. In fact, it is quite complicated, and either involves unintuitive subqueries, or unintuitive hacks. A normal DBA would not want to write, neither maintain this kind of query, unless top-notch-geek, which

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It might surprise you to hear this, but I had no idea whether my talks would be accepted. The committee decided on that, and neither I nor anyone else at Percona is on the committee. In any case, I’ll be giving some tutorials again this year, and two of my talks have been accepted: Measuring Scalability and Performance With TCP and Diagnosing intermittent performance problems.

This seems like an appropriate place to mention a few words about the conference organization. The number of people involved is staggering (100+). The

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Good news to all of you who are going or were thinking of going to the Percona Live MySQL Conference and Expo. Yesterday two great addon events were announced, both happening on Friday April 13th, right after the main conference:

Drizzle Day 2012

read more

common_schema, revision 218 is released, with major new features, top one being server side scripting. Here are the highlights:

• QueryScript: server side scripting is now supported by common_schema, which acts as an interpreter for QueryScript code.
• Throttling for queries is now made available via the throttle() function.
• Enhancements to processlist-related views, including the new slave_hosts view.
• Inline documentation/help is available via the help() routine.
• more...

QueryScript

common_schema makes for a QueryScript implementation for MySQL. You can run server side

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Introducing QueryScript: a programming language aimed for SQL scripting, seamlessly combining scripting power such as flow control & variables with standard SQL statements or RDBMS-specific commands.

QueryScript is available fro MySQL via common_schema, which adds MySQL-specific usage.

What does QueryScript look like? Here are a few code samples:

Turn a bulk DELETE operation into smaller tasks. Throttle in between.

while (DELETE FROM archive.events WHERE ts < CURDATE() LIMIT 1000)
{
  throttle 2;
}

Convert all InnoDB tables in the 'sakila' database to compressed format:

foreach ($table, $schema, $engine: table in sakila)
{
  if ($engine = 'InnoDB')
    ALTER TABLE

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In my day job at SkySQL I work with Drupal as our content management system.  One thing we often need to do is provide a way for people to sign up for events and the like.  One such event is the upcoming SkySQL and MariaDB: Solutions Day for the MySQL® Database and unlike other events we needed to take into account the dietary requirements of those wishing to attend.

For events registration we use the Signup module and use a theme template function to provide a set of standard fields.  The code looks something like this:

function ourtheme_signup_user_form($node) {
  $form = array();
  // If this function is providing any extra fields

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Henrik has already posted it over on the Drizzle Blog, but I thought I’d give a shout out here too.

We’re holding a Drizzle Day right after the Percona Live MySQL Conference and Expo in April. So, since you’re all like me and don’t book your travel this far in advance, it’ll be easy to stay for the extra day and come and learn awesome things about Drizzle.

I’m also pretty glad that my employer, Percona is sponsoring the event.

I’m scheduled to deliver several free MySQL webinars via Percona and ODTUG in the upcoming weeks. I hope you can join me:

• February 16 – Verifying Replication Integrity with Percona Toolkit via ODTUG.
• February 22 – EXPLAIN Demystified via Percona.
• March 14 – Optimizing MySQL Configuration via Percona.

Further Reading:

• Free webinar Wednesday: verifying replication integrity

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Hi Everyone,

Just a quick note to let you know that I've just finished up adding some new features to XtraBackup Manager.

You can now get better visibility into what is going on inside XtraBackup Manager with the "xbm status" command.

It will allow you to see which backup jobs are running and also those which may be waiting to start, due to the maximum number of concurrent backup tasks already running.

It looks/works as follows:

[xbm@localhost ~]$ xbm status

XtraBackup Manager v0.8 - Copyright 2011-2012 Marin Software

Currently Running Backups:

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In relation to this MPB post, there is a command to output data into a file and then to load it back into MySQL to resolve locks. (An example of a really big reporting query that could be quite heavy, can be found here.)

There is an issue with outputting data into a file through MySQL if the file already exists. For example:

mysql> use mysql
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A
Database changed 

mysql> select * from user into outfile '/tmp/user.sql';

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