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Analysis: A query with implicit grouping is one with aggregate functions and no GROUP BY clause. MariaDB inherits from MySQL an SQL extenstion that allows mixing aggregate functions with non-aggregate fields. If a query with such mixed select clause produces an empty result set, the meaning of aggregate functions is well defined - either NULL (MIN, MAX, etc.), or 0 (count(*)). However the non-aggregated fields must also have some value, and the only reasonable value in the case of empty result is NULL. The cause of the many wrong results was that if a field is declared as non-nullable (e.g. because it is a PK or NOT NULL), the semantic analysis and the optimization phases treat this field as non-nullable, and generate all related query plan elements based on this assumption. Later during execution, these incorrectly configured/generated query plan elements result in a wrong result because the selected fields are not null due to the not-null assumption during optimization. Solution: Detect before the context analysys phase that a query uses implicit grouping with mixed aggregates/non-aggregates, and set all fields as nullable. The parser already walks the SELECT clause, and already sets Item::with_sum_func for Items that reference aggreagate functions. The patch adds a symmetric Item::with_field so that all Items that reference an Item_field are marked during their construction at parse time in the same way as with aggregate function use.
This directory contains a test suite for the MySQL daemon. To run the currently existing test cases, simply execute ./mysql-test-run in this directory. It will fire up the newly built mysqld and test it. Note that you do not have to have to do "make install", and you could actually have a co-existing MySQL installation. The tests will not conflict with it. To run the test suite in a source directory, you must do make first. All tests must pass. If one or more of them fail on your system, please read the following manual section for instructions on how to report the problem: http://kb.askmonty.org/v/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, the test suite expects you to provide the 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 also need to provide --socket, --user, and other relevant options. With no test cases named on the command line, mysql-test-run falls back to the normal "non-extern" behavior. The reason for this is that some tests cannot run with an external server. You can create your own test cases. To create a test case, create a new file in the t 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. We would appreciate it if you name your test tables t1, t2, t3 ... (to not conflict too much with existing tables). 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 (like result file names) 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 cases consisting of SQL statements and comments, you can create the test case 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.com or attach it to a bug report on https://bugs.launchpad.net/maria/. 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.askmonty.org/private and send a mail to https://bugs.launchpad.net/maria/ about it.