mariadb-test Overview

The Basics

At its core, mariadb-test is very simple. The client program mariadb-test executes a test file and compares the produced output with the result file. If the files match, the test is passed; otherwise the test has failed. This approach can be used to test any SQL statement, as well as other executables (with the exec command).

The complete process of testing is governed and monitored by the driver script, or mtr for short (for convenience, mtr is created as a symbolic link to The mtr script is responsible for preparing the test environment, creating a list of all tests to run, running them, and producing the report at the end. It can run many tests in parallel, execute tests in an order which minimizes server restarts (as they are slow), run tests in a debugger or under valgrind or strace, and so on.

Test files are located in suites. A suite is a directory which contains test files, result files, and optional configuration files. The mtr looks for suites in the mariadb-test/suite directory, and in the mariadb-test subdirectories of plugins and storage engine directories. For example, the following are all valid suite paths:


In almost all cases, the suite directory name is the suite name. A notable historical exception is the main suite, which is located directly in the mariadb-test directory.

Test files have a .test extension and can be placed directly in the suite directory (for example, mariadb-test/suite/handler/interface.test) or in the t subdirectory (e.g. mariadb-test/suite/rpl/t/rpl_alter.test or mariadb-test/t/grant.test). Similarly, result files have the .result extension and can be placed either in the suite directory or in the r subdirectory.

A test file can include other files (with the source command). These included files can have any name and may be placed anywhere, but customarily they have a .inc extension and are located either in the suite directory or in the inc or include subdirectories (for example, mariadb-test/suite/handler/ or mariadb-test/include/

Other files which affect testing, while not being tests themselves, are:

  • disabled.def
  • suite.opt
  • other *.opt files
  • my.cnf
  • other *.cnf files
  • combinations
  • other *.combinations files
  • *.sh files
  • *.require files
  • *.rdiff files
  • valgrind.supp

See Auxiliary files for details on these.


In addition to regular suite directories, mtr supports overlays. An overlay is a directory with the same name as an existing suite, but which is located in a storage engine or plugin directory. For example, storage/myisam/mariadb-test/rpl could be a myisam overlay of the rpl suite in mariadb-test/suite/rpl. And plugin/daemon_example/mariadb-test/demo could be a daemon_example overlay of the demo suite in storage/example/mariadb-test/demo. As a special exception, an overlay of the main suite, should be called main, as in storage/pbxt/mariadb-test/main.

An overlay is like a second transparent layer in a graphics editor. It can obscure, extend, or modify the background image. Also, one may notice that an overlay is very close to a UnionFS, but implemented in perl inside mtr.

An overlay can replace almost any file in the overlaid suite, or add new files. For example, if some overlay of the main suite contains a include/ file, then all tests that include it will see and use the overlaid version. Or, an overlay can create a t/create.opt file (even though the main suite does not have such a file), and create.test will be executed with the specified additional options.

But adding an overlay never affects how the original suite is executed. That is, mtr always executes the original suite as if no overlay was present. And then, additionally, it executes a combined "union" of the overlay and the original suite. When doing that, mtr takes care to avoid re-executing tests that are not changed in the overlay. For example, creating t/create.opt in the overlay of the main suite will only cause create.test to be executed in the overlay. But creating suite.opt affects all tests and it will cause all tests to be re-executed with the new options.


In certain cases it makes sense to run a specific test or a group of tests several times with different server settings. This can be done using so-called combinations. Combinations are groups of settings that are used alternatively. A combinations file defines these alternatives using my.cnf syntax, for example




And all tests where this combinations file applies will be run three times: once for the combination called "row", and --binlog-format=row on the server command line, once for the "stmt" combination, and once for the "mix" combination.

More than one combinations file may be applicable to a given test file. In this case, mtr will run the test for all possible combinations of the given combinations. A test that uses replication (three combinations as above) and innodb (two combinations - innodb and xtradb), will be run six times.

Sample Output

Typical mtr output looks like this

TEST                                  WORKER RESULT   TIME (ms) or COMMENT
rpl.rpl_row_find_row_debug                [ skipped ]  Requires debug build
main-pbxt.connect                         [ skipped ]  No PBXT engine
main-pbxt.mysqlbinlog_row                 [ disabled ]  test expects a non-transactional engine
rpl.rpl_savepoint 'mix,xtradb'            w2 [ pass ]    238
rpl.rpl_stm_innodb 'innodb_plugin,row'    w1 [ skipped ]  Neither MIXED nor STATEMENT binlog format
binlog.binlog_sf 'stmt'                   w2 [ pass ]      7
unit.dbug                                 w2 [ pass ]      1
maria.small_blocksize                     w1 [ pass ]     23
sys_vars.autocommit_func3 'innodb_plugin' w1 [ pass ]      5
sys_vars.autocommit_func3 'xtradb'        w1 [ pass ]      6
main.ipv6                                 w1 [ pass ]    131

Every test is printed as "suitename.testname", and a suite name may include an overlay name (like in main-pbxt). After the test name, mtr prints combinations that were applied to this test, if any.

A similar syntax can be used on the mtr command line to specify what tests to run:

$ ./mtr innodbsearch for innodb test in every suite from the default list, and run all that was found.
$ ./mtr main.innodbrun the innodb test from the main suite
$ ./mtr main-pbxt.innodbrun the innodb test from the pbxt overlay of the main suite
$ ./mtr main-.innodbrun the innodb test from the main suite and all its overlays.
$ ./mtr main.innodb,xtradbrun the innodb test from the main suite, only in the xtradb combination
$ ./mtr --suite=rplRun all test in the rpl suite (found in the suite/rpl directory)
$ ./mtr --suite=mroonga/storageRun all test in the mroonga/wrapper suite (found in the storage/mroonga/mysql-test/mroonga/storage directory)

Plugin Support

The mtr driver has special support for MariaDB plugins.

First, on startup it copies or symlinks all dynamically-built plugins into var/plugins. This allows one to have many plugins loaded at the same time. For example, one can load Federated and InnoDB engines together. Also, mtr creates environment variables for every plugin with the corresponding plugin name. For example, if the InnoDB engine was built, $HA_INNODB_SO will be set to (or ha_innodb.dll on Windows). And the test can safely use the corresponding environment variable on all platforms to refer to a plugin file; it will always have the correct platform-dependent extension.

Second, when combining server command-line options (which may come from many different sources) into one long list before starting mariadbd, mtr treats --plugin-load specially. Normal server semantics is to use the latest value of any particular option on the command line. If one starts the server with, for example, --port=2000 --port=3000, the server will use the last value for the port, that is 3000. To allow different .opt files to require different plugins, mtr goes through the assembled server command line, and joins all --plugin-load options into one. Additionally it removes all empty --plugin-load options. For example, suppose a test is affected by three .opt files which contain, respectively:


...and, let's assume the Example engine was not built ($HA_EXAMPLE_SO is empty). Then the server will get:

instead of --plugin-load=

Third, to allow plugin sources to be simply copied into the plugin/ or storage/ directories, and still not affect existing tests (even if new plugins are statically linked into the server), mtr automatically disables all optional plugins on server startup. A plugin is optional if it can be disabled with the corresponding --skip-XXX server command-line option. Mandatory plugins, like MyISAM or MEMORY, do not have --skip-XXX options (e.g. there is no --skip-myisam option). This mtr behavior means that no plugin, statically or dynamically built, has any effect on the server unless it was explicitly enabled. A convenient way to enable a given plugin XXX for specific tests is to create a have_XXX.opt file which contains the necessary command-line options, and a file which checks whether a plugin was loaded. Then any test that needs this plugin can source the file and have the plugin loaded automatically.

mtr communication procedure

mtr is first creating the server socket (master).

After that, workers are created using fork().

For each worker run_worker() function is called, which is executing the following:

  • creates a new socket to connect to server_port obtained from the master
  • initiate communication with the master using START command
  • master sends first test from list of tests supplied by the user and immediately sends command TESTCASE to the worker
  • worker gets command TESTCASE and processes test case, by calling run_testcase() function which starts(/restarts if needed) the server and sends TESTRESULT (in case of restart WARNINGS command is issued to the master in case some warnings/error logs are found)
  • master accepts TESTRESULT command and run mtr_report_test() function which check does the test fail and also generates the new command TESTCASE if some new test case exist
  • If there is no other test case master sends BYE command which gets accepted by the worker which is properly closing the connection.


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