Momentum for MySQL Utilities continues to build.  I hosted a webinar recently about MySQL Utilities (available on-demand from the link below), which generated a lot of interest and some good questions.

http://event.on24.com/eventRegistration/EventLobbyServlet?target=lobby.jsp&eventid=448952&sessionid=1&key=7E741ED049DFBF49D10C90A2B62E410F&eventuserid=63530507

With so many questions and ideas coming in I decided to create a blog of FAQs. I plan to add these to the MySQL documentation as well.  Keep your ideas and questions coming!

I hope you find these questions enlightening. I have grouped them for easier reading. You can find the MySQL Utilities documentation using the link below. 

…

The mysqldiff and mysqldbcompare utilities were designed to produce a difference report for objects and in the case of mysqldbcompare the data. Thus, you can compare two databases and produce a report of the differences in both object definitions and data rows. 

While that may be very useful, would it not be much more useful to have the ability to produce SQL commands to transform databases? Wait no longer! The latest release of MySQL Utilities has added the ability to generate SQL transformation statements by both the mysqldiff and mysqldbcompare utilities. 

To generate SQL transformations in either utility, simply use the --sql option to tell the utility to produce the statements.

Object Transformations with mysqldiff

If you would like to compare the schema of two databases (the objects and their definitions), mysqldiff can do that for you and produce a difference report …

How To Back Up MySQL Databases With mylvmbackup On Debian Squeeze

mylvmbackup is a Perl script for quickly creating MySQL backups. It uses LVM's snapshot feature to do so. To perform a backup, mylvmbackup obtains a read lock on all tables and flushes all server caches to disk, creates a snapshot of the volume containing the MySQL data directory, and unlocks the tables again. This article shows how to use it on a Debian Squeeze server.

IMPORTANT note:
* This release requires a new registration code. Neither the 5.1x nor the pre-5.1x key will work with this. Registered customers will get the new code from our Customer Portal. Please have the new code available before installing. Until MONyog is registered with new keys, it will not be collecting data from your servers .

Features:
* Added filter for including or excluding specific hosts and(or) users in slow log analysis.
* Added and modified a few Monitors related to Replication, InnoDB and Security. Most of this utilizes metrics exposed by MySQL from version 5.5 .
* Added a preconfigured Custom SQL Object (CSO) for Percona Servers exposing the most written and most read tables.
* There is now session-wide persistence while sorting columns in Query Analyzer.
* Improved error messages in Query Analyzer and Wayback machine.
* Usability …

MongoDB Backup types and strategies are neatly explained in its documentation, which you can check here. In case you are not familiar with MongoDB backup types and strategies, please have a look at its documentation.

What I am describing here is a simple script which we are using since months to take MongoDB backup and transfer it over to our Backup server. Here are few things its doing:

• As we have multiple MongoDB Replica Sets, the script identify current replica set and check whether current server is Master or Slave, exit if its Master. We take backup only from Slave host.
• Take Backup using mongodump command.
• Upon successful completion of dump, transfer that to our Backup server. Ensure that ssh key based authentication is setup between both servers to implement seamless and secure transfer. It creates new directory based on …

These are things I like that I consider differences from last years conference. There are plenty of other things I like that don’t need to be listed here.

• The overall tone and feel of the conference was much less marking and much more technical
• Refreshingly honest keynotes. There was a lot of coming clean about the history of MySQL and the conference.
• Percona is very technical but it is also a business. They are very good about bringing out the technical and not being pushy about the business.
• No ice cream social. A thousand people shaking sticky hands with each other is never a good idea.
• percona.tv
• The conference was busy but never crowded

Now for the dislike:

• Only one song before every session.
• The chairs. Damn the chairs.
• Wifi failed more often than it worked. Most of the time I was tethered to my phone. …

[ Note: I haven't fully investigated this problem but the post has been hanging around in my queue for months. Rather than have it rot there I am publishing what I know in hopes that it helps someone else. ]

There are a lot of different kinds of locks in MySQL. Some of these locks are exposed to users such as intention locks, table locks, and row locks. There are other locks that aren’t exposed as well. These are mutexes that MySQL uses internally to protect resources from being modified by more than one thread at a time. These locks are numerous and complicated. When these locks deadlock mysql can stop dead in it’s tracks. The last deadlock I found happens when flush logs, show processlist, and a slave reconnect happen at the same time. I don’t have a core from the mysqld process, only stack traces. The breakdowns of stack traces are locks that I’m pretty sure the threads own and ones that they may be stuck trying on. I am working …

The recording and slides for my webinar on zero-downtime schema changes with MySQL are available now. Don’t miss Vadim’s webinar tomorrow!

Just as a reminder – tomorrow, May-9, 2012, at 11am PDT I will be giving a free webinar “MySQL and SSD”. This is the same talk I gave on Percona Live MySQL Conference, so if you were there – you probably will find nothing new. Otherwise, you are welcome to join!

Last month, Ronald Bradford, Giuseppe Maxia and Mark Leith spoke about how to simulate a mysqldump –ignore-database.
This mysqldump option doesn’t exist and these three guys have given us various helpful solutions.

But for those of us who use ZRM community to make backup with mysqldump, the –exclude-pattern seems to do the job :

--exclude-pattern "pattern" 
All databases or tables that match the pattern are not backed up. 
If --all-databases or --databases are specified, the exclude pattern applies
to …