MySQL 5.6 will now automatically recreate the InnoDB redo log files during a MySQL restart if the size (or number) of these logs changes, i.e. a change to innodb_log_file_size. See Changing the Number or Size of InnoDB Log Files which states “If InnoDB detects that the innodb_log_file_size differs from the redo log file size, it will write a log checkpoint, close and remove the old log files, create new log files at the requested size, and open the new log files.”

Before MySQL 5.6 it was necessary to stop MySQL and remove the InnoDB log files manually before restarting MySQL.

The error log shows:

tail -f /mysql/log/error.log
...
2015-03-28 21:51:25 3767 [Warning] InnoDB: Resizing redo log from 2*3072 to 2*65536 pages, LSN=1626017
2015-03-28 21:51:25 3767 [Warning] InnoDB: Starting to delete and …

Mermaids have the same probability of fixing your permission problems, but people continue believing in the FLUSH PRIVILEGES myth.I see suggesting the usage of FLUSH PRIVILEGES every time someone writes a tutorial or a solution to a problem regarding creating a new account or providing different privileges. For example, the top post on /r/mysql as of the writing of these lines, “MySQL:The user specified as a definer does not exist (error 1449)-Solutions” has multiple guilty cases of this (Update: the user has corrected those lines after I posted this article).

It is not my intention to bash that post, but I have seen …

Check Out Our Latest Technical Resources for MySQL, MariaDB, Postgres and MongoDB.

This blog is packed with all the latest resources and tools we’ve recently published! Please do check it out and let us know if you have any comments or feedback.

New Technical Live Webinar

• What: Deep-dive into How to Monitor Galera Cluster
• When: Tuesday April 21st
• Who: Krzysztof Książek, Senior Support Engineer, Severalnines
• Where: Register Here

Join our colleague Krzysztof Książek for a deep-dive session what to monitor in Galera Cluster for MySQL & MariaDB. Krzysztof is a MySQL DBA with experience managing complex database environments for companies like Zendesk, …

Can we output content of a mariaDB table into JSON using the CONNECT Storage Engine ? MariaDB and MySQL are not currently JSON friendly databases. The usage of JSON in MySQL is almost inexistent with the excetion of the explain JSON output and of MariaDB dynamic column dump. There also exist a few udf (in [...]

Years ago when I worked for the MySQL Support organization at the original MySQL AB, we spoke about MySQL Support as insurance and focused on a value proposition similar to that of car insurance. For your car to be fully covered, you must purchase car insurance before the incident happens – in fact most places around the world require automobile insurance. Similarly with many organizations, any production-use technology might be mandated to have its own insurance in the way of 24/7 support.

I think however this is a very one-sided view that does not capture the full value (and ROI) that a MySQL Support contract with Percona provides. Let’s look at the different dimensions of value it provides based on the different support cases we have received throughout the years.

Reduce and Prevent …

Thu, 2015-04-02 12:02jean-françoisgagné

(The previous post, Better Parallel Replication for MySQL, is Part 1 of the series.) Parallel replication is a much expected feature of MySQL. It is already available in MariaDB 10.0 and in MySQL 5.7. In this post, a very nice side effect of the MariaDB implementation is presented: Slave Group Commit.

(If you are not familiar with parallel replication and its implementation, read the previous post in this series to better understand this post.)

To allow better parallelization on slaves, MariaDB 10.0 and MySQL 5.7 have parameters that control the commit group sizes on the master. Those parameters are …

I contributed an article on modern database storage engines to the recent DZone Guide To Database and Persistence Management. I’m cross-posting the article below with DZone’s permission.

Readers of this guide already know the database world is undergoing rapid change. From relational-only, to NoSQL and Big Data, the technologies we use for data storage and retrieval today are much different from even five years ago.

Today’s datasets are so large, and the workloads so demanding, that one-size-fits-all databases rarely make much sense. When a small inefficiency is multiplied by a huge dataset, the opportunity to use a specialized database to save money, improve performance, and optimize for developer productivity and happiness can be very large. And today’s solid-state …

I contributed an article on modern database storage engines to the recent DZone Guide To Database and Persistence Management. I’m cross-posting the article below with DZone’s permission.

Readers of this guide already know the database world is undergoing rapid change. From relational-only, to NoSQL and Big Data, the technologies we use for data storage and retrieval today are much different from even five years ago.

Today’s datasets are so large, and the workloads so demanding, that one-size-fits-all databases rarely make much sense. When a small inefficiency is multiplied by a huge dataset, the opportunity to use a specialized database to save money, improve performance, and optimize for developer productivity and happiness can be very large. And today’s solid-state …

A friends table is the cornerstone of social applications. Its purpose is to define relationships and help answer the question what are my friends doing.

Here is an example friend’s table:

 CREATE TABLE `friends` (
  `user_id` bigint(20) unsigned NOT NULL,
  `friend_id` bigint(20) unsigned NOT NULL,
  `auto_ts` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,
  PRIMARY KEY (`user_id`,`friend_id`),
  KEY `user_id-auto_ts` (`user_id`,`auto_ts`),
  KEY `friend_id-auto_ts` (`friend_id`,`auto_ts`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci


With the table above we can get a list of user_ids a user follows (following), or a list of people who follow said user (followers), or get a list of mutual follows. This is a very simple table structure yet very powerful.
…

We are excited to announce that VividCortex now supports Redis, a popular open source database. After announcing PostgreSQL support in January, our brainiacs continue to create a unified solution for diverse systems.

Baron Schwartz explains the product development further. “Redis is an important database for VividCortex, both strategically and commercially, due to its incredible popularity and our own usage. We rely on Redis to help analyze the massive amounts of time-series data we receive from agents running on customer systems. Although it is a high-performance and reliable system that generally just works, that doesn’t mean it can’t be improved. We were able to significantly optimize our usage of Redis with the network-traffic visibility built into our agents. Most of our …