MariaDB Galera server logs all the cluster related information like node status, cluster status, membership, etc. in the error log. MariaDB 10.1.2 introduces a new INFORMATION SCHEMA plugin WSREP_INFO that enables querying these information via INFORMATION SCHEMA tables. The WSREP_INFO plugin adds two new tables to the Information Schema, WSREP_MEMBERSHIP and WSREP_STATUS. The plugin is not enabled by default, so in order to use it, it needs to be installed first :

Now that WSREP_INFO plugin is installed, lets look into the contents of these tables on a 3-node cluster.

As seen above, WSREP_MEMBERSHIP table shows information about current members in the cluster which includes node’s name and incoming address. WSREP_STATUS table, on the other hand, shows status information about the node and cluster as a whole.

SHOW command can also be used to query these tables. Its quick and reduces the number of columns for WSREP_STATUS to fit to the screen.

One thing which we, as developers of MariaDB, run into is that our personal database needs are not the same as many of our users. In fact, our needs are quite light compared to many. We have a MariaDB website, a company website, a knowledgebase, this blog, and that’s about it. None of them are particularly high traffic compared to what our customers have. But apart from talking to our customers, which are just a small percentage of the total MariaDB population, we wanted to have a way of finding out how MariaDB is used “in the real world”, so to speak.

Asking lots and lots of people to fill out surveys isn’t any fun, and we would have to keep repeating the survey ad nauseum to get useful information over time on trends and such. So many years ago (around 2003 or 2004), we came up with an idea of implementing a “phone home” feature in MySQL. It had an unfortunate fate — everyone agreed that we needed it, but, apparently, there was never a good time for implementing it. And we — in MySQL — kept on developing the features that we supposed you might want, without the statistics that would help us know what you actually needed.

But we can stop guessing now. Let me announce the User Feedback plugin, it’s included in the just-released MariaDB 5.3.2-beta. This plugin is disabled by default, but we hope many of you will enable it. The statistics gathered will help us determine where to focus our development efforts and we think they will prove beneficial, or at least interesting, to everyone else. (What? You thought we were going to keep all of the information to ourselves?)

More information on the plugin can be found at http://kb.askmonty.org/en/user-feedback-plugin and some nice charts will eventually be available for your viewing pleasure at: http://mariadb.org/feedback_plugin/. I say eventually because if you go there now, there’s not much to look at, what with the plugin being just released and all.

The statistics gathered include things like buffer sizes, CPU architecture, OS, kernel version, what plugins are enabled, how much memory is installed, and so on. The statistics are all anonymous and contain no sensitive or private information. The information is collected into the information_schema.feedback table (and if you have the plugin enabled you can see what has been collected with a simple SELECT * FROM information_schema.feedback query). Once enabled, the Feedback plugin will automatically send a report a few minutes after startup and then once a week. Submitting is done via an HTTP POST (just like a web form).

Even if you choose not to submit anonymous statistics to mariadb.org, you may still find the plugin useful, especially if you run many instances of MariaDB. You see, the URL the plugin POSTs to is configurable. The default is to post to mariadb.org, but you can easily change it to POST to your own server, or to your own server and mariadb.org (you can configure multiple URLs).

For paranoid folks out there (and a good DBA should be a little bit paranoid) we have provided many different ways to ensure that the plugin only sends what we say it does — anonymous usage statistics. You can configure multiple report URLs, can see the HTTP traffic with a network sniffer, and can even submit the data manually using a web browser if you so choose.

Full details on configuring the plugin, and how to enable it, are available at http://kb.askmonty.org/en/user-feedback-plugin.

So, if you’ve ever wanted to help out with MariaDB, but just couldn’t think of anything, here’s something that everyone who runs MariaDB can do without breaking a sweat. Help us help you by enabling the User Feedback plugin!

Thanks.