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Showing entries 1 to 10 of 33114 10 Older Entries
Changing the DEFINER of MySQL stored routines etc.
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Mon, 2014-09-22 12:19hartmut

The question seemed easy enough:

We've dropped a user, now we want to change the DEFINER on all database objects that currently have it set to this dropped user?

This should be possible by checking the INFORMATION_SCHEMA tables of the appropriate object types (routines, triggers, views and events) and performing an ALTER on each of them that just modifies the DEFINER but nothing else, right?

Unfortunately it isn't that easy, or at least not yet (see http://bugs.mysql.com/73894 and https://mariadb.atlassian.net/browse/MDEV-6731 ).

Events are closest to this as ALTER EVENT does support changing the definer, but it also

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PagerDuty Incident Alerting for ClusterControl
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September 22, 2014 By Severalnines

Need to add phone and SMS alerting to ClusterControl? ClusterControl 1.2.8 introduces support for PagerDuty, an alerting service for Ops teams to schedule on-calls and add phone and SMS notifications to IT tools. By integrating PagerDuty with ClusterControl, you can start receiving phone, SMS and email notifications for all important database events as monitored by ClusterControl. Alerts go directly to the right person who can solve the issue.

This integration is possible thanks to a new plugin interface, that takes ClusterControl alarms in JSON format and outputs to an external system via plugins. Plugins can be either scripts or

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How to start Percona Xtradb Cluster on CentOS 7
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Normally, when we want to start PXC (Percona XtraDB Cluster) on RHEL/CentOS 6 or older then that, we can simply start with init.d script or service command. i.e shell> /etc/init.d/mysql start OR shell> /etc/init.d/mysql bootstrap-pxc shell> service mysql start. But, Continue reading →   [Read more...]
Using Netlink to Optimize Socket Statistics
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This is a story of using low-level kernel interfaces to optimize an edge case one of our agents encountered in some servers. The TL;DR version is that accessing /proc/ can be very expensive if there are a lot of network connections, and the Netlink interface between userspace and kernel space is a much more efficient method.

Background

VividCortex runs several agents, each specialized to a set of tasks. There’s one for gathering operating system metrics, called vc-os-metrics. We capture per-process metrics in the same high resolution as all of our metrics, because in many cases a performance problem is due to a process causing collateral damage to another process by hogging resources. In addition to per-process metrics, we gather a lot of other

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Downgrading from MySQL 5.6 to MySQL 5.5
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Last week I had to downgrade from MySQL 5.6 to 5.5. The reason for this was that the application used a very old Connector/J and that's incompatible with MySQL 5.6 because the removal of SET OPTION syntax.

We're now planning to upgrade Connector/J to be able to upgrade to 5.6 again.

There are two methods of downgrading:
  • Dump/Restore with mysqldump. This is easy and reliable, but can take more time.
  • In place (replace binaries, don't change data). This fast, but won't work if file formats have changed.
As expected this is documented in the MySQL Reference Manual.

I went for the in place method. I expected this to work without many issues as this database was not using the fancy new features like fulltext indexes for






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CIS Oracle MySQL 5.6 Security Benchmark
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I've been working on the CIS security benchmark for Oracle MySQL 5.6. There already is a benchmark document for earlier versions of MySQL.

The benchmark document helps you to ensure you have a secure configuration for MySQL.

Center for Internet Security (CIS) is a nonprofit organization.

The Call For Participation is now open.

If you are already a CIS member then you can download the document here. If you don't have an account you can register for free.
What part of NoSQL don't you understand?
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In the word "NoSQL", the letters "No" are an acronym so the meaning is "Not Only SQL" rather than "No SQL". True or false?

Historically, it's false

The first NoSQL product was a classic DBMS which didn't happen to use SQL for a query language, featured in Linux Journal in 1999. Its current web page has a traffic-sign symbol of the word SQL with a bar through it, and a title "NoSQL: a non-SQL RDBMS".

For a meetup in June 2009 about "open source, distributed, non-relational databases" the question came up "What's a good name?" Eric Evans of Rackspace suggested NoSQL, a suggestion which

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MySQL Performance: More in depth with LinkBench Workload on MySQL 5.7, MariaDB 10.1 and also Percona Server 5.6
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This is the next chapter of the story started in my previous article and related to the updated results on LinkBench workload published by MariaDB..

Keeping in mind that the obtained results are completely opposite from both sides, I've started to investigate then the same LinkBench-150GB 64 concurrent users workload from the "most favorable" possible test conditions on the same 40cores-HT server as in my previous article:

  • InnoDB Buffer Pool (BP) = 150G (so, all the data may remain in memory)



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MySQL upgrade best practices
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MySQL upgrades are necessary tasks and we field a variety of questions here at Percona Support regarding MySQL upgrade best practices. This post highlights recommended ways to upgrade MySQL in different scenarios.

Why are MySQL upgrades needed? The reasons are many and include: Access to new features, performance benefits, bug fixes…. However, MySQL upgrades can be risky if not tested extensively beforehand with your application because the process might break it, prevent the application from functioning properly – or performance issues could arise following the upgrade. Moreover, I suggest keeping an eye on

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MySQL Thread Pool Improvements @ Twitter
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At Twitter, MySQL is an important part of our storage story. We can have a typical database node with thousands of open connections. It works mostly fine because generally only a few of these connections actively working inside the server. Given the scale at which we have to operate spikes happen – mostly at unexpected times and with unexpected ferocity. The challenge is how to control concurrency within MySQL server during spikes.

Historically we have been using innodb_thread_concurrency to control number of active threads within the server. In Twitter MySQL-5.5 we introduced the idea of Query Throttling where incoming requests are throttled if the number of active threads goes beyond a configurable threshold. These solutions focus on maintaining the health of the system.

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Showing entries 1 to 10 of 33114 10 Older Entries

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