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10 Newer Entries Showing entries 71 to 80 of 33583 10 Older Entries
Multi-source Replication with MariaDB Galera Cluster
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December 1, 2014 By Severalnines

MariaDB 10 supports multi-source replication, and each MariaDB Galera node can have up to 64 masters connected to it. So it is possible to use a MariaDB Cluster as an aggregator for many single-instance MariaDB master servers.

In this blog post, we are going to show you how to setup multi-source replication with MariaDB Galera Cluster, where one of the Galera nodes is acting as slave to 3 MariaDB masters (see diagram below). If you would like to set this up with Percona XtraDB Cluster or Galera Cluster (Codership), please read …

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Security improvements in MySQL 5.7
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If you have a look on the last mysql 5.7.4 version or later you will probably see that there are several security improvements. The list of added security features and improvements can be seen on the following page:

There are three main improvements that are shortly described in this blog:

1. Nonempty plugin column
2. Password lifetime policy
3. mysql_install_db secured


Nonempty plugin column

As of MySQL 5.7.2, the server …

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It does not matter if Aurora performs 1x or 10x MySQL: it _is_ a big thing
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I spent the last 4 years at SkySQL/MariaDB working on versions of MySQL that could be “suitable for the cloud”. I strongly believed that the world needed a version of MySQL that could work in the cloud even better than its comparable version on bare metal. Users and administrators wanted to benefit from the use of cloud infrastructures and at the same time they wanted to achieve the same performance and overall stability of their installations on bare metal. Unfortunately, ACID-compliant databases in the cloud suffer from the issues that any centrally controlled and strictly persistent system can get when hosted on highly distributed and …

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Log Buffer #399, A Carnival of the Vanities for DBAs
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This Log Buffer Edition brings some freshly picked blog posts right out of the gardens of Oracle, SQL Server and MySQL.


Suppose you have a process A that you want to run faster. This process doesn’t commit (much), so it doesn’t wait on log file sync. However, there is another multi-threaded process, B, that commits very frequently, and spends a lot of time on “log file sync”.

New Solaris 11 CPU package to install and track …

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MySQL Installer 5.5
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MySQL Installer 5.5 (5.5.41 GA, published on Friday, 28 Nov 2014)

Oracle AVDF - Database Firewall Policies
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The successful deployment of a Database Firewall depends on an effective policy. Oracle AVDF includes preconfigured firewall policies as described in the Firewall Policy page in the Policy tab of the Audit Vault Server console.

These include policies that log all SQL statements, or log only unique SQL statements. In addition, the Database Firewall policy editor enables you to design your own policies quickly and efficiently.

Policy rules can depend on any combination of the SQL statement type, name of the database user, IP address of the database client, operating system user name, client program name, or any exceptions you …

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How to mess up your data using ONE command in MySQL/Galera.
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Or how wsrep_on can bring you to have a cluster with usless data.

This is a WARNING article, and it comes out after I have being working on define internal blueprint on how to perform DDL operation using RSU safely.

The fun, if fun we want to call it, comes as usual by the fact that I am a curious guy and I often do things my way and not always following the official instructions.

Anyhow, lets us go straight to the point and describe what can happen on ANY MySQL/Galera installation.

The environment

The test environment, MySQL/Galera (Percona PXC 5.6.20 version). …

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Full table scans and MySQL performance
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High season is coming, how do you make sure that MySQL will handle the increased load? Stress tests could help with that, but it’s not a good idea to run them in a production environment. In this case Select_scan, Select_full_join and other MySQL counters could quickly give you an idea of how many queries are not performing well and could cause a performance degradation as the load goes up.

Select_scan from SHOW GLOBAL STATUS indicates how many full table scans were done since last MySQL restart. Scanning the entire table is a resource intensive operation. It also forces MySQL to store unnecessary data in the buffer pool, wasting memory and IO …

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MySQL benchmarking: Know your baseline variance!
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Often enough I find MySQL benchmark results where the difference between results is 1% or even less and some conclusions are drawn. Now it is not that 1% is not important – especially when you’re developing the product you should care about those 1% improvements or regressions because they tend to add up. However with such a small difference it is very important to understand whenever this is for real or it is just the natural variance for your baseline test.

Take a look at this graph:
Click the image for a larger view)


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Nasty MySQL Replication Bugs that Affect Upgrade to 5.6
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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 …

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10 Newer Entries Showing entries 71 to 80 of 33583 10 Older Entries

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