There were two nasty MySQL replication bugs in two different 5.6 releases that would make it difficult to upgrade slaves to MySQL 5.6 while still connected to MySQL 5.5 master.

The first of those bugs is MySQL bug 72610 which affects 5.6.19. Essentially this bug is triggered when the table structure on the slave is different from the table structure on the master which leads to unnecessarily large amount of RAM usage while replicating events that affect that table. The amount of RAM used would generally be more noticeable when the replicated transaction consists of thousands of RBR events.

The most common way this affects how we upgrade a replication hierarchy, is when we have the master running MySQL 5.5 and the slave running MySQL 5.6 and we have transactions involving DATETIME column(s). Tables with DATETIME columns will have different …

With the query rewrite framework in the latest MySQL (Optimizer/InnoDB/Replication) labs release, you get the opportunity to author plugins that can rewrite queries. You can choose whether to rewrite the queries before and/or after parsing. Today I am going to walk you through how to write a pre-parse query rewrite plugin.

When would you want to use a pre-parse query rewrite plugin? The greatest benefit compared to post-parse rewrites — which I cover in a separate post — is the efficiency, especially the lack of overhead for those queries that are actually rewritten. Typical cases where you may want to write a pre-parse plugin are:

• When you want to remove certain specific clauses from queries. For example, perhaps you want to remove all ENGINE …

I log into a lot of different servers running MySQL and one of the first things I do is create a file in my home directory called ‘.my.cnf’ with my credentials to that local mysql instance:

[client]
user=root
password=secret

This means I don’t have to type my password in every time, nor am I tempted to include it on the command line with -p and get the dreaded (but completely accurate):

Warning: Using a password on the command line interface can be insecure.

MySQL 5.6 introduces a utility to make this easier and more secure. First, let’s start with a new mysqld instance with a blank root password and make it more secure:

[vagrant@localhost ~]$ mysqladmin -u root password
New password:secret
Confirm new password:secret
[vagrant@localhost ~]$ mysql -u root
ERROR 1045 (28000): Access denied for user …

I've blogged about common_schema multiple times in the past, and it's a tool I use frequently. Last week I had a project to delete millions of rows from multiple rollup tables in a star schema. Since the tables are not partitioned I needed to use DELETE instead of DROP PARTITION, but I didn't want to delete millions of rows in a single transaction. My first instinct was to use common_schema's split() function to break the deletes into chunks. So I ran a query on …

I just pushed the new Java based iiBench for MySQL (and Percona Server and MariaDB), the code and documentation are available now in the iibench-mysql Github repo. Pull request are welcome!

The history of iiBench goes back to the early days of Tokutek. Since "indexed insertion" is a strength of Fractal Tree indexes, the first iiBench was created by Tokutek in C++ back in 2008. Mark Callaghan rewrote iiBench in Python, adding several features along the way. His version of iiBench is available in …

This Log Buffer Edition covers some informative and interesting posts from Oracle, SQL Server and the MySQL.

Oracle:

If you’re not using Toad DBA Suite, it’s sometimes hard to find solutions. Somebody wanted to know how to find indexes that aren’t that aren’t indirect. Indirect indexes are those created for a primary key because a primary key column or set of columns are both not null and uniquely constrained. You can’t drop a unique index for a primary key without dropping the primary key constraint that indirectly created it.

At the NoCOUG fall conference at the eBay town hall in San Jose, we got a first-hand look at the workings of …

Helsinki, Finland – 24 NOVEMBER 2014 – Codership, whose Galera Cluster technology brings high availability to open source databases worldwide, today announced it has been named as a Red Herring’s 2014 Top 100 Global Winner . This prestigious recognition honours the year’s most audacious and far-reaching private technology companies and entrepreneurs across the globe.

Red Herring’s Top 100 Global list has become a mark of distinction for identifying promising new companies and entrepreneurs. Red Herring editors were among the first to recognize that companies such as Facebook, Twitter, Google, Yahoo, Skype, Salesforce.com, YouTube, and eBay would change the way we live and work.

“Choosing the companies with the strongest potential …

Creating a simple Load Balance client for a MySQL Cluster

There are few key points in using the Connector/J with Load Balancing on MySQL Cluster
- Dynamic JMX with Connector/J

• loadBalanceEnableJMX=true&loadBalanceConnectionGroup=<group>

- Timeout value in the blacklist with Connector/J

• loadBalanceBlacklistTimeout

The following code piece is used on my notebook with MySQL Cluster running on 2 x VMs.  IPs for accessing the 2 MySQL Nodes on the Cluster are 192.168.56.104 and 192.168.56.105.   The port number with the 2 x MySQL Nodes are the same with the value of "3306".

Here is the MySQL Cluster status with MySQL Cluster Manager (MCM)



…

People using OpenStack Trove instances can hit a common issue in the MySQL world: how to perform schema change operations while minimizing the impact on the database server? Let’s explore the options that can allow online schema changes.

Summary

With MySQL 5.5, pt-online-schema-change from Percona Toolkit is your best option for large tables while regular ALTER TABLE statements are only acceptable for small tables. Also beware of metadata locks.

With MySQL 5.6, almost all types of schema changes can be done online. Metadata locks can also be an issue. pt-online-schema-change can still be worth using as it is also online on read replicas.

Regular ALTER TABLE with MySQL 5.5

If you are still using MySQL 5.5, almost all schema changes will require a table …

Did you ever encounter swap space issue with MySQL ? This problem is really annoying and here are some possible solutions :

1) Track memory usage.. Try to identify the bottleneck using query below. It is not trivial job to zero in on the problem heap.. There are several temp tables being created at run time. Also estimating the OS cache being used by system MYISAM tables is not easy

SELECT ( @@key_buffer_size + @@query_cache_size + @@innodb_buffer_pool_size + @@innodb_additional_mem_pool_size + @@innodb_log_buffer_size + 80 * ( @@read_buffer_size + @@read_rnd_buffer_size + @@sort_buffer_size + @@join_buffer_size + @@binlog_cache_size + @@thread_stack + @@tmp_table_size ) ) / (1024 * 1024 * 1024) AS MAX_MEMORY_GB;

2) Configure the swappiness to 10 or 15.. By default it might be set at 60

cat /proc/sys/vm/swappiness will give the current swappiness value on your system

3) Set Numa interleaving to ON. …