In the MySQL team, we have been planning for some time to remove the implicit sorting that is provided by GROUP BY. In doing so, we will make a number of existing queries faster (by no longer requiring a sort) as well as unlock opportunities to implement further optimizations.

This is one of the more complicated behaviours to remove, because it is not possible to tell if an application relies upon implicit ordering. Since a GROUP BY query without an ORDER BY clause is a valid query, it is also not reasonable to issue deprecation warnings.

However, one piece of the puzzle that was missing when I last wrote about this problem, is that MySQL 5.7 will …

This Log Buffer Edition gathers a wide sample of blogs and then purifies the best ones from Oracle, SQL Server and MySQL.

Oracle:

• If you take a look at the “alter user” command in the old 9i documentation, you’ll see this: DEFAULT ROLE Clause.
• There’s been an interesting recent discussion on the OTN Database forum regarding “Index blank blocks after a large update that was rolled back.”
• 12c Parallel Execution New Features: 1 SLAVE distribution
• Index Tree Dumps in Oracle 12c …

It was a very long time since I wrote something in this blob, but I have been very busy this spring with MariaDB on Power mostly. This has been a lot of work, but also a lot of fun. So, what is this MariaDB on Power thing all about, well I wrote an introduction to the Power platform late last year. Since then a lot of things has happened though.

One thing is that several service providers out there has adopted Power8 as a platform. To be honest, this really isn't sexy, but it is useful and as a user of one of these services, you will just see the same old Linux you are used to, but potentially it is more powerful and reliable. One such provider is OVH, whose service is more known as RunAbove. If you want to try it, you can do so for free for 7 7 days, just go …

The slides of “Efficient Use of Indexes in MySQL” talk we delivered on SFMySQL Meetup.

This is an introductory talk for developers on MySQL indexes. In my opinion it’s quite important to understand how InnoDB organizes data. If you know how MySQL accesses data it’s easier to write optimal queries.

When working with queries I imagine secondary indexes as a table with records sorted by secondary key fields. This is a powerful concept that helps to understand MySQL logic. It’s also easy to understand complex optimizations like loose index scan.

For example, for index (last_name, rank) the secondary index table looks like:

…

We received feedback from a number of users in the MySQL community that the command SHOW ENGINE INNODB MUTEX remains useful in a number of scenarios. We listened, and the command is scheduled to make a return in MySQL 5.7.8.

To lessen overhead, the command will now feature a mechanism to enable and disable metrics collection. This is documented in the manual here:

SET GLOBAL innodb_monitor_enable='latch';
SET GLOBAL innodb_monitor_disable='latch';

Thank you for helping make a better MySQL!

VMware Continuent enables demanding enterprise customers to process billions of business-critical transactions using economical MySQL relational databases. Learn how VMware Continuent adds high-availability, disaster recovery, and real-time data warehouse loading to off-the-shelf MySQL operating in vCloud Air. 

We introduce vCloud Air basics, then do a deep dive into the VMware Continuent system

The following new license is now in effect:
SWANHART OPEN LICENSE
Clause #1:
The following companies:
Percona staffing llc, and any associated parent, child or ancillary entities

May not download, retain, install, operate, or in any way associate themselves with this software. This is without exception. Any use must immediately and permanently cease. Violation of this license will be pursued in a court of law.

The remainder of the license is normal 3 clause BSD. The above preamble overrides any relevant clauses in that license with respect to rights to use the software.

Long live MariaDB!

Database schema changes are not popular among DBAs, not when you are operating production databases and cannot afford to switch off the service during a maintenance window. These are unfortunately frequent and necessary, especially when introducing new features to existing applications. 

Schema changes can be performed in different ways, with tradeoffs such as complexity versus performance or availability. For instance, some methods would trigger a full table rewrite which could lead to high server load. This in turn would lead to degraded performance and increased replication lag in master-slave replication setups. 

This is the fourth installment in the ‘Become a MySQL DBA’ series, and discusses the different approaches to schema changes in MySQL. Our previous posts in the DBA series include High …

A Note On Good Practice

Even though I’ve been developing for some time now it never ceases to amaze me how many people don’t comment in their code. Most of us have fallen into the trap of “the code is self explanatory.” Sure, sometimes it is: if you’re writing “Hello World.” Even that can be questionable at times.

I once interviewed a seasoned developer who, when asked about how they document, replied “I think code should be self documenting.” I wanted to slap my forehead and send them packing right away. Code is never self-documenting. Never. Especially when you go back to it 4 weeks later. And if you think it is self documenting, the poor sap who has to maintain your code doesn’t.

With that said, I would like to make a plea to all non-documenters out there with good reasons on why you want to document.

Why Document? Visual Resting Place

Great …

Are your databases more costly than they need to be? If you’re not sure, this webinar will show you how to find out, quickly and easily, with KPIs that indicate overprovisioning or opportunity for driving more efficiency from your databases.

Join us on July 9th at 2 PM EST (6 PM GMT), as Baron discusses database cost reduction. The key topics you’ll learn are:

• Evaluating your current efficiency.
• Determining if there’s an opportunity to lower your database costs.
• Five simple steps to achieve maximum cost efficiency from your databases: query efficiency, consolidation, reduction of diversity, right-sizing, and cloud computing.
• For each step you’ll learn how to find out whether it applies to your situation, and how to take action on it.

After this webinar, you’ll understand how to measure, assess, and sometimes lower the cost of your database …