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In essence this means that we expect the user query to have at least one matching row in the end. This change will not affect the estimated rows for the plan, but will ensure that the cost for adding a table is not neglected because of record count being too low. The reasons for this is that if we have table combination that together has a very high selectivity then join record_count could become very low (close to 0) This would cause costs for all future tables to be so small that they are irrelevant for the rest of the plan. This has been shown to be the case in some performance benchmarks and in a few mtr tests. There is also still a problem in selectivity calculations as joining two tables in different order causes a different estimation of total rows. This can be seen in selectivity_innodb.test, test 'Q20' where joining nation,supplier is expecting 1.111 rows_out while joining supplier,nation is expecting 0.04 rows_out. The reason for 0.04 is that the optimizer estimates 'supplier' to have 10 matching rows, and joining with nation (eq_ref) has 1 row. However selectivity of n_name = 'UNITED STATES' makes the optimizer things that there will be only 0.04 matching rows. This patch avoids this "too low row count" to affect cost caclulations. |
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.. | ||
collections | ||
include | ||
lib | ||
main | ||
std_data | ||
suite | ||
asan.supp | ||
CMakeLists.txt | ||
dgcov.pl | ||
lsan.supp | ||
mariadb-stress-test.pl | ||
mariadb-test-run.pl | ||
mtr.out-of-source | ||
purify.supp | ||
README | ||
README-gcov | ||
README.stress | ||
suite.pm | ||
valgrind.supp |
This directory contains test suites for the MariaDB server. To run currently existing test cases, execute ./mysql-test-run in this directory. Some tests are known to fail on some platforms or be otherwise unreliable. In the file collections/smoke_test there is a list of tests that are expected to be stable. In general you do not have to have to do "make install", and you can have a co-existing MariaDB installation, the tests will not conflict with it. To run the tests in a source directory, you must do "make" first. In Red Hat distributions, you should run the script as user "mysql". The user is created with nologin shell, so the best bet is something like # su - # cd /usr/share/mysql-test # su -s /bin/bash mysql -c ./mysql-test-run This will use the installed MariaDB executables, but will run a private copy of the server process (using data files within /usr/share/mysql-test), so you need not start the mysqld service beforehand. You can omit --skip-test-list option if you want to check whether the listed failures occur for you. To clean up afterwards, remove the created "var" subdirectory, e.g. # su -s /bin/bash - mysql -c "rm -rf /usr/share/mysql-test/var" If tests fail on your system, please read the following manual section for instructions on how to report the problem: https://mariadb.com/kb/en/reporting-bugs If you want to use an already running MySQL server for specific tests, use the --extern option to mysql-test-run. Please note that in this mode, you are expected to provide names of the tests to run. For example, here is the command to run the "alias" and "analyze" tests with an external server: # mysql-test-run --extern socket=/tmp/mysql.sock alias analyze To match your setup, you might need to provide other relevant options. With no test names on the command line, mysql-test-run will attempt to execute the default set of tests, which will certainly fail, because many tests cannot run with an external server (they need to control the options with which the server is started, restart the server during execution, etc.) You can create your own test cases. To create a test case, create a new file in the main subdirectory using a text editor. The file should have a .test extension. For example: # xemacs t/test_case_name.test In the file, put a set of SQL statements that create some tables, load test data, and run some queries to manipulate it. Your test should begin by dropping the tables you are going to create and end by dropping them again. This ensures that you can run the test over and over again. If you are using mysqltest commands in your test case, you should create the result file as follows: # mysql-test-run --record test_case_name or # mysqltest --record < t/test_case_name.test If you only have a simple test case consisting of SQL statements and comments, you can create the result file in one of the following ways: # mysql-test-run --record test_case_name # mysql test < t/test_case_name.test > r/test_case_name.result # mysqltest --record --database test --result-file=r/test_case_name.result < t/test_case_name.test When this is done, take a look at r/test_case_name.result. If the result is incorrect, you have found a bug. In this case, you should edit the test result to the correct results so that we can verify that the bug is corrected in future releases. If you want to submit your test case you can send it to maria-developers@lists.launchpad.net or attach it to a bug report on https://mariadb.org/jira/. If the test case is really big or if it contains 'not public' data, then put your .test file and .result file(s) into a tar.gz archive, add a README that explains the problem, ftp the archive to ftp://ftp.mariadb.org/private and submit a report to https://mariadb.org/jira about it. The latest information about mysql-test-run can be found at: https://mariadb.com/kb/en/mariadb/mysqltest/ If you want to create .rdiff files, check https://mariadb.com/kb/en/mariadb/mysql-test-auxiliary-files/