#DBHangOps 03/19/15 -- Failing over in the moment, Old and weird bugs, and more!

Hello everybody!

Join in #DBHangOps this Thursday, March, 19, 2015 at 11:00am pacific (19:00 GMT), to participate in the discussion about:

• Failing over in the moment

  • How do you recognize you need to failover?
  • When is it safe to kill -9 the server?
  • Other thoughts?
• Old/Weird bugs!
• GTID for operators -- Have you set it up?

You can check out the event page at https://plus.google.com/events/ch7dvhercc2anl9knnvig02hng4 on Thursday to participate.

As always, you can still watch the #DBHangOps twitter …

I love finding out new things about MySQL. Last week, I stumbled on a query that had the phrase “SOUNDS LIKE” in it. Sounds made-up, right? Turns out MySQL is using a known “soundex” algorithm common to most databases, and popular in use cases in geneaology.

The basic idea is that words are encoded according to their consonants. Consonants that sound similar (like M and N) are given the same code. Here’s a simple example:

(“soundex” and “sounds like” are different ways of doing the same thing in these queries)

MariaDB> select soundex("boom");
+-----------------+
| soundex("boom") |
+-----------------+
| B500            |
+-----------------+

MariaDB> select soundex("bam");
+----------------+
| soundex("bam") |
+----------------+
| B500           |
+----------------+

MariaDB> select soundex("bin");
+----------------+
| soundex("bin") |
+----------------+
| B500           |
+----------------+

…

This Log Buffer Edition picks the sea shells from Blogs across the seas of Oracle, SQL Server and MySQL and arrange them for you in this Edition. Enjoy.

Oracle:

12c Parallel Execution New Features: Concurrent UNION ALL

Visualizing Statspack Performance Data in SQL Developer

Optimizer statistics – Gathering Statistics and Histograms

Big Data Made Actionable with Omar TawaKol at SXSW

Mobile …

Mon, 2015-03-16 11:20jean-françoisgagné

Parallel replication is a much-expected feature of MySQL. It’s available in MariaDB 10.0 and in MySQL 5.7. Yet, both lose efficiency when replicating through intermediate masters. In this post, we’ll explain how parallel replication works and why it does not play well with intermediate masters. We’ll also offer a solution (hint: it involves Binlog Servers).

In MySQL 5.5 and MariaDB 5.5, replication is single threaded: on a slave, the previous transaction must complete (commit) before the next transaction can start. This is not the case on a master where many transactions can make progress at the same time. The consequence is that a slave has less transaction processing capabilities than its master (for writes). This means that care must be taken to avoid loading a master with …

Over on the codecentric blog I just published a new post on True KVM Live Migration with OpenStack Icehouse and Ceph based VM storage, outlining the process it took me to get this actually working. There were several issues to work around, some of them bugs in OpenStack, some of them home-grown issues.

I provide a few patches to OpenStack classes as well as a description of what is actually going wrong and how to circumvent the problems. So head right over and have fun reading :)

One of our Percona Support customers recently reported that Percona XtraBackup failed with a page corruption error on an InnoDB table. The customer thought it was a problem or bug in the Percona XtraBackup tool. After investigation we found that an InnoDB page was actually corrupted and a Percona XtraBackup tool caught the error as expected and hence the backup job failed.

I thought this would be an interesting topic and worthy of a blog post. In this article I will describe the innochecksum tool, when and how to use it and what are the possible fixes if an InnoDB table suffers from …

PostgreSQL’s approach to automatic numbering is as simple as Oracle but different than MySQL, and Microsoft SQL Server. For example, you have a two-step process with Oracle, PostgreSQL, MySQL, and Microsoft SQL Server. First, you create an Oracle table with the GENERATED AS IDENTITY clause, a PostgreSQL table with the SERIAL data type, a MySQL table with the AUTO_INCREMENT clause, and a Microsoft SQL Server table with the IDENTITY(1,1) clause. Then, you need to write an INSERT statement for Oracle, MySQL, or Microsoft SQL Server like:

1. Oracle’s INSERT statement excludes the auto-incrementing column from the list of columns or provides a NULL value in the VALUES-list. You can then assign the RETURNING INTO result from an INSERT statement to a session-level (bind) variable.
2. MySQL’s …

On March 10, 2015, we released MySQL-5.7.6 and among many other things it includes multi-source replication which …

One of my customers wants to search for names in a table. But sometimes the search is case insensitive, next time search should be done case sensitive. The index on that column always is created with the collation of the column. And if you search with a different collation in mind, you end up with a full table scan. Here is an example:

The problem

 mysql> SHOW CREATE TABLE City\G  
 *************************** 1. row ***************************  
 Table: City  
 Create Table: CREATE TABLE `City` (  
 `ID` int(11) NOT NULL AUTO_INCREMENT,  
 `Name` char(35) CHARACTER SET utf8 COLLATE utf8_bin DEFAULT NULL,  
 `CountryCode` char(3) NOT NULL DEFAULT '',  
 `District` char(20) NOT NULL DEFAULT '',  
 `Population` int(11) NOT NULL DEFAULT '0',  
 PRIMARY KEY (`ID`),  
 KEY `CountryCode` (`CountryCode`),  
 KEY `Name` (`Name`),  
 ) ENGINE=InnoDB AUTO_INCREMENT=4080 DEFAULT CHARSET=latin1  
 1 row in set (0,00 sec)  

…

http://blog.booking.com/better_parallel_replication_for_mysql.html

Follow the link above to read my latest article on the Booking.com developer blog.  It is about MySQL Parallel Replication and Binlog Servers.

This fulfills my promise made at Percona Live London 2014 during my talk High Availability, Disaster Recovery and Extreme Read Scaling using Binlog Servers: I finally took the time to