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Displaying posts with tag: configuration (reset)

Changes in Configuration of Global Variables between MySQL 5.6.20 and MySQL 5.7.4 “Milestone 14″
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While doing some testing (that I have pending to show you) on the still-in-development MySQL 5.7 I wanted to do some analysis on the configuration to see if the changes in performance were due to the code changes or just to the new MySQL defaults (something that is very common in the migration from 5.5 to 5.6 due to the default transaction log size and other InnoDB parameters). This is a quick post aiming to identify the global variables changed between these two versions.

You could tell me that you could just read the release notes, but my experience (and this is not an exception,

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Configuring MySQL to use minimal memory
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I've been experimenting with MySQL Fabric - the official tool in development to provide HA and sharding. Part of this experimentation has meant that I have been running 7 copies of the MySQL Server on my laptop at once, which can consume a lot of memory

So today I wanted to write about how to configure MySQL to use less memory, which may also be beneficial in situations where peak performance is not important. For example: a developer VM environment.

Previous configuration guides

Before I get started, let me point to some of my previous configuration guides:

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How to Enable MySQL Event Scheduler
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You may think that you already know what's the opposite of "DISABLED", but with MySQL Event Scheduler you'll be wrong.

In fact MySQL Event Scheduler may have three different states[1][2]:

DISABLED -  The Event Scheduler thread does not run [1]. In addition, the Event Scheduler state cannot be changed at runtime.
OFF (default) - The Event Scheduler thread does not run [1]. When the Event Scheduler is OFF it can be started by setting the value of event_scheduler to ON.
ON - The Event Scheduler is started; the event scheduler thread runs and executes all scheduled events.

So if you're going to find it in the DISABLED state and instinctively set it to ENABLED you'll end up with a non-starting MySQL daemon.
Be warned and stay safe out there!


[1]: http://dev.mysql.com/doc/refman/5.5/en/events-configuration.html
[2]: When the Event Scheduler is not running does not appear in the output of SHOW PROCESSLIST
TokuDB configuration variables of interest
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During our experiments I came upon a few TokuDB variables of interest; if you are using TokuDB you might want to look into these:

  • tokudb_analyze_time

This is a boundary on the number of seconds an ANALYZE TABLE will operate on each index on each partition on a TokuDB table.

That is, if tokudb_analyze_time = 5, and your table has 4 indexes (including PRIMARY) and 7 partitions, then the total runtime is limited to 5*4*7 = 140 seconds.

Default in 7.1.0: 5 seconds

  • tokudb_cache_size

Similar to innodb_buffer_pool_size, this variable sets the amount of memory allocated by TokuDB for caching pages. Like InnoDB the table is clustered within

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Understanding gcache in Galera
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October 16, 2013 By Severalnines

Galera uses a preallocated file with a specific size called gcache, used to store the writesets in circular buffer style. By default, its size is 128MB. In this post, we are going to explore how to leverage gcache to improve the operation of a Galera cluster.

 

Test Case

 

We have a four node Galera cluster, using the latest release 23.2.7(r157). We have a table called t1 that is replicated by Galera on all nodes. The cluster nodes have allocated the default 128MB gcache.size, and we’ll try to execute a large writeset to see how gcache responds.

mysql> 
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On MySQL plugin configuration
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MySQL offers plugin API, with which you can add different types of plugins to the server. The API is roughly the same for all plugin types: you implement an init() function, a deinit(); you declare status variables and global variables associated with your plugin, and of course you implement the particular implementation of plugin call.

I wish to discuss the creation and use of global variables for plugins.

Consider the following declaration of a global variable in audit_login:

static MYSQL_SYSVAR_BOOL(enabled, plugin_enabled, PLUGIN_VAR_NOCMDARG,
"enable/disable the plugin's operation, namely writing to file", NULL, NULL, 1);

static struct
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How to Scale Joomla on Multiple Servers
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July 2, 2013 By Severalnines

Joomla! is estimated to be the second most used CMS on the internet after WordPress, with users like eBay, IKEA, Sony, McDonald’s and Pizza Hut. In this post, we will describe how to scale Joomla on multiple servers. This architecture not only allows the CMS to handle more users, by load-balancing traffic across multiple servers. It also brings high availability by providing fail-over between servers.

 

This post is similar to our previous posts on web application scalability and high availability:

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Some new (and useful!!) MySQL 5.6 variables
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Upgrading from MySQL 5.5 to MySQL 5.6 is a fairly straightforward process. However, the move to version 5.6 does bring with it some new varaibles with which to work.

One of the recent innovations (pioneered by Percona in Percona Server 5.5 if I recall correctly) is the ability to "dump" the innodb buffer pool***. This can be done any time MySQL is running and can be configured to be executed during MySQL shutdown. One reason to do this is to have a server "pre-warmed" when you perform a server restart. Why this is important is that during server operation the innodb buffer pool will fill up. Typically the server will operate much better when this buffer pool is full instead of being empty or paritally full because the return of data from the buffer pool is much faster than returning data from disk. 

There are four important variables with each

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Scaling Wordpress and MySQL on Multiple Servers for Performance
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June 11, 2013 By Severalnines

Over the years, WordPress has evolved from a simple blogging platform to a CMS. Over seven million sites use it today, including the likes of CNN, Forbes, The New York Times and eBay. So, how do you scale Wordpress on multiple servers for high performance? 

 

This post is similar to our previous post on Drupal, Scaling Drupal on Multiple Servers with Galera Cluster for MySQL but we will focus on Wordpress, Percona XtraDB Cluster and GlusterFS using Debian Squeeze 64bit.

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MySQL updates, openSUSE 13.1 and default configuration
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Recently I had some time to do some clenaups/changes/updates in server:database repo regarding MySQL (and MariaDB). Nothing too big. Well actually, there are few little things that I want to talk about and that is the reason for this blog post, but still, nothing really important…

MySQL 5.5, 5.6 and 5.7

MySQL 5.6 is stable for some time already, so it’s time to put it in the action. So I sent the request to include it in Factory and therefore in openSUSE 13.1. There is off course a list of

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