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Displaying posts with tag: Learning (reset)
Lesson 09: Managing Users and Privileges in MySQL

Notes/errata/updates for Chapter 9:
See the official book errata at http://tahaghoghi.com/LearningMySQL/errata.php – Chapter 9 includes pages 297 – 350.

In the fourth paragraph of this chapter, starting with “Most applications don’t need superuser privileges for day-to-day activities” they give you some reasons why you want to create users without the SUPER privilege. There are better reasons than the book gives, which are at the MySQL Manual page for the SUPER privilege.

In the section “Creating and Using New Users” (p. 300) they say “There’s no limit on password length, but we recommend using eight or fewer characters because this avoids problems with system libraries on some platforms.” You should ignore this, this book …

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Lesson 07: Advanced MySQL Querying

Notes/errata/updates for Chapter 7:
See the official book errata at http://tahaghoghi.com/LearningMySQL/errata.php – Chapter 7 includes pages 223 – 275.

Supplemental blog post – ORDER BY NULL – read the blog post and the comments!

GROUP BY and HAVING examples – Supplemental blog post. The example of HAVING in the text shows a use case where HAVING is the same function as WHERE. This blog posts shows examples of HAVING that you cannot do any other way.

In the section called “The GROUP BY clause”, on pages 231-232, the book says:
“you can count any column in a group, and you’ll get the same answer, so COUNT(artist_name) is the same as …

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Lesson 06: Working with Database Structures

Notes/errata/updates for Chapter 6:
See the official book errata at http://tahaghoghi.com/LearningMySQL/errata.php – Chapter 6 includes pages 179 – 222.

Other notes:
At the end of the “Creating Tables” section (p.183-4), it says “We like using the underscore character to separate words, but that’s just a matter of style and taste; you could use underscores or dashes, or omit the word-separating formatting altogether.” While this is true, beware of using a dash, because MySQL will try to interpret “two-words”, thinking – is a minus sign. I recommend avoiding dashes for this reason (even though the book does this on page 215).

At the end of the “Collation and Character Sets” section (p.186), it says “When you’re creating a database, you can set the default character set and sort order for the database and its …

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MySQL Marinate – So you want to learn MySQL! – START HERE

Want to learn or refresh yourself on MySQL? MySQL Marinate is the FREE virtual self-study group is for you!

MySQL Marinate quick links if you know what it is all about.

This is for beginners – If you have no experience with MySQL, or if you are a developer that wants to learn how to administer MySQL, or an administrator that wants to learn how to query MySQL, this course is what you want. If you are not a beginner, you will likely still learn some nuances, and it will be easy and fast to do. If you have absolutely zero experience with MySQL, this is perfect for you. The first few chapters walk you through getting and installing MySQL, so all you need is a computer and the book.

The format of a virtual self-study group is as follows:
Each participant acquires the same textbook ( …

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Testing Advanced Log Flushing for Percona Audit

We use Percona’s <A HREF=”https://www.percona.com/doc/percona-server/5.5/management/audit_log_plugin.html”>audit log plugin</A> to keep a record of all our logins. Recently we did one of those tasks that everyone knows they should do, but few ever do: change the application user’s password.

When we change the application password, we add a new application user with the proper permissions and a new password, update the information in our repository and wait a while. Using this procedure, any failures mean the old user is used, and more importantly – failure does not impact the end user.

We check the audit logs to see if there were failures – if the user is still being used – when it is no longer in use, we can drop the user.

For reference, here are our settings:

[mysqlaudit]# …

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MySQL DevOps First Step: Revision Control

MySQL environments are notorious for being understaffed – MySQL is everywhere, and an organization is lucky if they have one full-time DBA, as opposed to a developer or sysadmin/SRE responsible for it.

That being said, MySQL is a complex program and it’s useful to have a record of configuration changes made. Not just for compliance and auditing, but sometimes – even if you’re the only person who works on the system – you want to know “when was that variable changed?” In the past, I’ve relied on the timestamp on the file when I was the lone DBA, but that is a terrible idea.

I am going to talk about configuration changes in this post, mostly because change control for configuration (usually /etc/my.cnf) is sorely lacking in many organizations. Having a record of data changes falls under backups and binary logging, and having a record of schema changes is something many organizations integrate with their ORM, so …

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Generating a MySQL Password

One of the services our database engineers provide is adding users to MySQL. We have some nice Chef recipes, so all I have to do is update a few files, including adding in the MySQL password hash.

Now, when I added myself, I just logged into MySQL and generated a password hash. But when my SRE (systems reliability engineer) colleague needed to generate a password, he did not have a MySQL system he could login to.

The good news is it’s easy to generate a MySQL password hash. The MySQL password hash is simply a SHA1 hash of a SHA1 hash, with * at the beginning. Which means you do not need a MySQL database to create a MySQL password hash – all you need is a programming language that has a SHA1 function (well, and a concatenate function).

And I found it, of course, on this post at StackExchange (http://unix.stackexchange.com/a/234592/217471). So you don’t have to click through, here is what it says – and I have …

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New MySQL Online Training

Oracle University recently unveiled a new online training offering – the MySQL Learning Subscription.  The combination of freely-accessible and compelling paid content makes this an exciting development to me, and should prove valuable to the community and customer base alike.  This post will briefly explore this new MySQL educational resource.

Organization

The subscription content is organized into topical “channels”.  Current top-level channels are:

  • Getting Started
  • Development
  • Administration
  • Security

These channels have sub-channels as well – for example, the Getting Started channel includes Getting Started With MySQL New Features and MySQL For Beginners, …

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OurSQL Episode 189: Syncing Both Ways

This week we discuss advanced pt-table-sync, including bidirectional sync. Ear Candy is starting MySQL on low-memory virtual machines, and At the Movies is "What's New With MySQL and MariaDB?"

pt-table-sync
Episode 188, where we talked about pt-table-sync basics
pt-table-sync documentation

Options discussed:
--bidirectional
--chunk-column
--conflict-column
--conflict-comparison - greatest, least, newest, oldest, equals, matches
--conflict-value
--conflict-error

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OurSQL Episode 188: Back in Sync

This week we discuss pt-table-sync basics. Ear Candy is about how MyISAM can seem transaction-aware, and At the Movies is MySQL and NoSQL at Craigslist.

Events
DB Hangops - every other Wednesay at noon Pacific time
Upcoming SkySQL events
Upcoming MySQL events

OSCon 2014 will be held at the Oregon Convention Center in Portland, Oregon from Sunday July 20th through Thursday July 24th.

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