My fellow testers and others who run RQG tests on MySQL flavors might be interested in some additions that are being used for MariaDB testing. While none of them is a major breakthrough, maybe they will make somebody’s life a little easier.

RQG Introduction

A quick introduction for those who have never heard of RQG, but are still curious what this blog post is about.

RQG stands for Random Query Generator, also known as randgen — an open-source product, available under the GPL v2 license. Quoting its home page on Launchpad, it is a “pseudo-random data and query generator that can be used to test any Perl DBI, JDBC or ODBC-compatible SQL server, in particular MySQL, but also JavaDB and PostgreSQL”.

The framework was created by my former colleague Philip Stoev, who not only developed a great tool, but also managed to make it a very important part of the MySQL testing routine. I think by now all MySQL-based products use it to some extent; and to those that don’t, I recommend to try it out.

Along with data and query generation, the framework features “pluggable” modules of different types, which perform various checks during or after test execution. This article is mainly about adding more of them to the existing set. When you see ‘validator’ or ‘reporter’ below, it means the type of the corresponding module.

RQG documentation can be found on GitHub.

About these MariaDB additions

All listed additions have been pushed into the main randgen tree on Launchpad, along with some other stuff that is more specific for MariaDB and thus less interesting for the general public. However by the time you are reading it, those versions might already be a little outdated. Since the randgen tree is now self-regulated, I feel like it can easily fall into the “too many cooks” trap, so I have chosen the most conservative approach for merging into the main tree. Whenever a change affects anything but a MariaDB-specific component, I will send an email to the randgen mailing list with the description, and if there is at least one voice against the change, it will not be merged. The downside is that it makes merges a bit fussy, so will not be happening often. Moreover, rejected changes will never make it to the main tree.

Most recent versions, as well as all new and rejected patches can be found in our work tree.

Galera mode

RQG is very useful for running tests on a Galera cluster, but doing it is a pain: start all the nodes, run an instance of RQG for each node, check results, don’t forget to shut down the nodes at the end… Probably most of us who have had to do it by now have scripted some parts of it, but still, it felt all wrong, so I finally decided to make it “native”. Now Galera cluster can be started by RQG itself, with a topology configurable via a command-line option.


This is just the first drop, which is likely to be fixed and improved later.

CheckFieldValue validator

If you need a simple one-time check that does not deserve implementing a separate validator, you might try this one.

Adding a specifically formatted comment to a query triggers a validation. The validation is defined in the comment itself: it says which field in which row in the result set should be checked, and provides the condition (currently simple numeric comparison: ‘=‘, ‘<‘, ‘>‘, ‘<=‘, ‘>=‘).


Here is a real example of how it can be used: MDEV-4578. A user reports sporadic bizarre values in I_S.processlist.time field. You can of course write a validator for it, and I initially did, but I soon realized that it was inconvenient since I wanted to keep modifying the checking query. So instead I added the SELECT from the I_S to the grammar, with the condition that the time field must be less than some ridiculously big value.

The set of possible validations will be expanded on need basis.

SlaveCrashRecovery reporter

The reporter is for testing crash-safety of master=>slave replication. It crashes the slave periodically, restarts it and makes sure it starts all right.


I am using it, along with its sibling MariadbGtidCrashSafety reporter, for testing MariaDB implementation of GTID.

BinlogConsistency reporter

The reporter checks that the contents of the binary log(s) correctly reflects the data at the end of the test flow. After the main test flow is finished, the reporter creates a data dump of the server, shuts down the server, starts a new one with the same options, but on a clean data directory, replays binary logs of the first server into the new one, creates a data dump of the new server, and compares it with the previous dump.


I was using it for testing of binlog changes in MariaDB 10.0 (see for example MDEV-181, MDEV-232)

CrashRecovery reporter

A new implementation of the old Recovery reporter, more suitable for current server versions. Instead of hard-coded set of options for the restarted server, it uses the same configuration as the initial server had.


Comparison of VIEW Algorithms

RQG allowed to configure a view type to be used during the test, but you could only create views of the same type on servers that you were comparing. I found it to be a shortage while testing the extension of MERGE views implemented in MariaDB 10.0 (see MDEV-3862): I needed to compare MERGE views on one server with TEMPTABLE views on another server. So, --views1 and --views2 options have now been added. It might be not the most elegant solution, but it is in line with other similar options in RQG, and it does the trick.


Multiple redefining grammars

I found that my set of redefining grammars started growing beyond reason because I only could provide one at a time, and often I would need to combine several, so I would have to create a new grammar for each combination.
So, now you can add as many --redefine= options as you want, all grammars will be applied on top of the main grammar.


New grammar keywords _basetable and _view

The RQG keyword _table means any table or view from the test dataset. Often it’s good enough, but sometimes it badly increases the number of erroneous statements, e.g. with the “not a base table” error. Now tables and views can be differentiated in a grammar depending on what the goal is: _table can still be used for both tables and views, while _basetable will only pick tables, and _view will only pick views.



If you have a feedback on the changes, you can leave comments at RQG extensions for MariaDB Features.

The Board of the MariaDB Foundation thought it would be good to provide an update — hopefully the first of a regular quarterly series — on how we’re progressing with the interim activities around constructing governance, identifying a new representative Board and structuring an engineering council.

  • The MariaDB Foundation is now independent of any business interests. With the acquisition of Monty Program Ab by SkySQL Ab, there’s now a clear separation of functions. The Foundation is the home of community activity around MariaDB, dedicated to sustaining and delivering the MariaDB database on behalf of its community independently of the business interests of any member. We are acting as a US 501(c)(6) not-for-profit and intend to follow the advice we have received to formally register with the IRS at the start of 2014.
  • Support from commercial backers is steadily flowing; you can see some of them listed on our new Supporters page, which is still being updated. We have two different kinds of supporters.
    • Commercial Sponsors are businesses within the MariaDB Community who want to team together to keep the infrastructure and administration running. In return, we offer them recognition via our Supporters Page.
    • Commercial Members are businesses within the MariaDB Community who additionally want to participate directly in the governance oversight. They will be helping the Board through our new Advisory List and will also be identifying up to half of the members of the new Board when we switch to permanent governance (the other half will be community contributors to the code). I’m pleased to have three generous supporters in this category already.
    • While we now have a good number of Commercial Sponsors, we still need more and I encourage you to offer sponsorship if your business uses MariaDB. If you have a high strategic dependence on MariaDB, I encourage you to consider Commercial Membership.
  • We have a small staff team in place. I’m acting as CEO in the interim period on a part-time basis, with Monty serving as my CTO and structuring our engineering functions. Working for him are two developers and a part-time administrator, with a current focus on documentation. We also have a General Counsel, Andrew Katz, supported by US attorney Andy Updegrove, and we’re retaining a “virtual CFO” through Virtual Management, Inc. I expect to add a membership director and further developers to the team in the coming months. I hope our overall staff team will peak at about 8 FTE by the end of the year.
  • The interim Board has met regularly. It comprises Sergei Golubchik, Rasmus Johansson, Andrew Katz, myself, Monty Widenius and Jeremy Zawodny. Since the governance we envisage is based on the Eclipse Foundation, we have also invited its executive director Mike Milinkovich to attend all our meetings as an advisor.
  • The Board is keen for MariaDB to play a full part in the wider community of open source communities. Consequently, we have now joined the Open Source Initiative as an Affiliate Member, and we have become a licensee of the Open Invention Network.
  • We’re now ready to start the next key element of the Foundation’s transformation, establishing community-based governance. We expect the permanent governance for the Foundation to reflect both the developer and business needs of the MariaDB Community, with the Board being equally divided between community-recognised technical contributors to MariaDB and Corporate Members. We plan to conduct public discussion of new Bylaws during August 2013.
  • We’re just starting discussion of how to structure an engineering council to act as the focus for consensus around MariaDB itself, very much along the lines of the current MariaDB Captains. We have not discussed any proposal to make any changes to the licensing of MariaDB and I don’t expect any such proposal to be made; we’re sticking with the GPL. Rather, I’m expecting the community around MariaDB to continue to strengthen and grow as an open community.

If you would like to discuss any aspect of the Foundation with me – especially if your company would like to become a Sponsor or Member — please get in touch. My e-mail address is webmink at mariadb org.

I’m pleased to say that the Open Source Initiative Board has accepted the MariaDB Foundation’s application to become an Affiliate Member of OSI. The MariaDB Foundation Board decided to join OSI to demonstrate our support for the principle of software freedom and to be able to participate in OSI projects more directly under their new Working Group mechanism. MariaDB community members are of course still invited to become individual members of OSI!