I will be speaking about MySQL at the Bulgarian Oracle Users Group's Spring Conference.

In furthering my mission to increase the MySQL knowledge among my countrymen I will try to give the grand tour of all the modern MySQL administrative and development tools that the MySQL team provides.

This will be the 3d BGOUG conference I'm speaking to. And I expect no less than the stellar organization and the great audience that I had the privilege to interact with during the previous 2 conferences.

We had a lot of fun too ! Parties from the last 2 conferences are …

We recently hosted a live webinar covering advanced MySQL Replication topics as well as the latest developments. The webinar charts and replay are now available here. Below, you’ll find the questions raised by the audience together with the responses given.

More details on what was covered…

The biggest Web sites in the world rely on MySQL Replication to scale-out and provide High Availability for their data. Extend your knowledge of how MySQL Replication works and what you can achieve with it; join us for this technical webinar to explore some of the more advanced replication architectures as well as some of the latest product developments:

• Replication …

We have seen TokuDB lock escalation stall the execution of SQL operations for tens of seconds. To address this problem, we changed the lock escalation algorithm used by TokuDB and TokuMX so that the cost of lock escalation only affects big transactions. We also eliminated a serialization point when running lock escalation.

Transactions in TokuDB and TokuMX accumulate locks on key ranges while they execute. These locks allow multiple transactions to run concurrently. The locks are released when the transaction commits or aborts.

The locks are stored in an in memory data structure that contains a set of key range and transaction identifier pairs. Since the locks are stored in memory and we want to support arbitrarily large transactions, an algorithm is needed to kick in when the amount of memory used to store locks exceeds a maximum limit. The limit is set when the server is started. The lock escalation algorithm shrinks the total …

OPTIMIZE TABLE is a maintenance operation used to recover the disk space and improve IO efficiency. It is recommended that the operation is carried out under the cases noted in the optimize table documentation.

MySQL versions prior to MySQL 5.6.17 does not allow concurrent changes (inserts, updates, deletes) to the table when the OPTIMIZE TABLE operation is being performed on that table. This causes downtime for user applications and is relatively high for large tables.

OPTIMIZE TABLE for INNODB or PARTITIONED INNODB tables used ALTER TABLE FORCE operation internally to address the fragmentation problem prior to MySQL 5.6.17. This involves doing a table copy and taking a strong lock in the SQL-layer which blocks all concurrent changes to the table, thus causing the downtime.

MySQL supports online rebuild of tables within the storage …

Facebook, the undisputed king of online social networks, has 1.23 billion monthly active users collectively contributing to an ocean of data-intensive tasks – making the company one of the world’s top MySQL users.

A small army of Facebook MySQL experts will be converging on Santa Clara, Calif. next week where several of them are leading sessions at the Percona Live MySQL Conference and Expo. I had the chance to chat virtually with four of them about their sessions: Steaphan Greene, Evan Elias, …

March 27, 2014 By Severalnines

With datacenters being stretched by resource-intensive applications, more and more businesses are outgrowing their existing in-house capacity and having to reconfigure their IT operations. But how do you migrate a busy application to a totally new data center without downtime? How will the application scale in a virtualized cloud environment? And how do you guard against cloud server failures and keep a high level of uptime?

In this example, we will show you how to migrate a Web application (Wordpress) from a local data center to a AWS VPC. Without downtime even! 

Main steps:

• Setup the cloud servers (for web server + database)
• Install Galera Cluster and ClusterControl
• Setup MySQL replication between the single instance MySQL (local) to Galera Cluster (remote)
• Sync your application …

I ran into an interesting issue today, while examining some EXPLAIN outputs, and wanted to share the findings, as some of this is undocumented.

Basically, you can start with a very simple InnoDB table – 2 INT columns, Primary Key (PK) on the 1st column, regular index on the 2nd:

CREATE TABLE `t1` (
  `id1` int(10) unsigned NOT NULL,
  `id2` int(10) unsigned DEFAULT NULL,
  PRIMARY KEY (`id1`),
  KEY `id2` (`id2`)
) ENGINE=InnoDB;

The query is:

SELECT id1 FROM t1;

This is a straight-forward query with no WHERE clause.

Given no WHERE clause, we know there will be a full table or index scan. Let’s look at EXPLAIN:

mysql> EXPLAIN SELECT id1 FROM t1\G
*************************** 1. row ***************************
           id: 1
  select_type: SIMPLE
        table: t1
         type: index
possible_keys: NULL
          key: id2
      key_len: 5
          ref: NULL
         rows: 1 …

Recently, I have worked on one of this case where customer wanted to convert master-slave to master-master replication. They wanted to write on one master and keep another master as a hotspare. Many people are using this kind of environment with MySQL replication.

I would like to explain here in very simple steps that how we can do that. You can also follow the same steps if you want to promote only slave as a master in master-slave replication. Sometimes, this process will be helpful if you have master-slave replication and you want to rebuild or upgrade both the servers one by one. In that case, you have to shift traffic from one server to the other, take down the first server, rebuild it and then reverse the process.

I would also like to mention here that  master-master (active-active) replication is quite risky and it can lead to data inconsistency between the servers if writes are enable on both masters at the same time. …

The Percona Live MySQL Conference and Expo 2014 runs April 1-4  at the Santa Clara Convention Center and Santa Clara Hyatt – but be sure to get there a day early for the inaugural Open Source Appreciation Day on March 31 – this event is free but because space is limited I suggest registering now to reserve your spot.

Interest is particularly high in OpenStack and its intersection with MySQL and Open Source Appreciation Day and the conference sessions and events reflect this. Last year, the Percona Live MySQL Conference included 4 talks with Trove (“Red Dwarf” at the time) as the …

Based in Luxembourg, AlSego is an Independent Software Vendor delivering Web, e-Commerce and financial applications including:

• A Rapid Application Development (RAD) and Business Process Oriented (BPO) Web Server Platform.
• E-payment and e-banking "Plug & Play" solutions.
• Archiving solutions for the banks' SWIFT data.

AlSego counts some of the largest banks in Luxembourg, Belgium and Switzerland among its clients and partners.

Challenges

• Supporting multiple database platforms for its products' master repositories generated a relatively high number of technical support incidents as end-users did not always master the various technologies involved. This in turn increased costs for both customers and AlSego, and negatively impacted the customer experience.
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