bff9b1e472
Nullability is decided in two stages- 1. Based on argument NULL-ness Problem: - COALESCE currently uses a generic logic- "Result of a function is nullable if any of the arguments is nullable", which is wrong. - IFNULL sets nullability using second argument alone, which incorrectly sets the result to NULL even when first argument is not null. Fix: - Result of COALESCE and IFNULL is set to NULL only if all arguments are NULL. 2. Based on type conversion safety of fallback value Problem: - The generic `Item_hybrid_func_fix_attributes` logic would mark the function's result as nullable if any argument involved a type conversion that could yield NULL. Fix: - For COALESCE and IFNULL, nullability is set to NOT NULL if the first non-null argument can be safely converted to function's target return type. - For other functions, if any argument's conversion to target type could result in NULL, the function is marked nullable. Tests included in `mysql-test/main/func_hybrid_type.test`
Code status:
ci.appveyor.com
MariaDB: The innovative open source database
MariaDB was designed as a drop-in replacement of MySQL(R) with more features, new storage engines, fewer bugs, and better performance.
MariaDB is brought to you by the MariaDB Foundation and the MariaDB Corporation. Please read the CREDITS file for details about the MariaDB Foundation, and who is developing MariaDB.
MariaDB is developed by many of the original developers of MySQL who now work for the MariaDB Corporation, the MariaDB Foundation and by many people in the community.
MySQL, which is the base of MariaDB, is a product and trademark of Oracle Corporation, Inc. For a list of developers and other contributors, see the Credits appendix. You can also run 'SHOW authors' to get a list of active contributors.
A description of the MariaDB project and a manual can be found at:
https://mariadb.com/kb/en/mariadb-vs-mysql-features/
https://mariadb.com/kb/en/mariadb-versus-mysql-compatibility/
https://mariadb.com/kb/en/new-and-old-releases/
Getting the code, building it and testing it
Refer to the following guide: https://mariadb.org/get-involved/getting-started-for-developers/get-code-build-test/ which outlines how to build the source code correctly and run the MariaDB testing framework, as well as which branch to target for your contributions.
Help
More help is available from the Maria Discuss mailing list https://lists.mariadb.org/postorius/lists/discuss.lists.mariadb.org/ and MariaDB's Zulip instance, https://mariadb.zulipchat.com/
Licensing
MariaDB is specifically available only under version 2 of the GNU General Public License (GPLv2). (I.e. Without the "any later version" clause.) This is inherited from MySQL. Please see the README file in the MySQL distribution for more information.
License information can be found in the COPYING file. Third party license information can be found in the THIRDPARTY file.
Bug Reports
Bug and/or error reports regarding MariaDB should be submitted at: https://jira.mariadb.org
For reporting security vulnerabilities see: https://mariadb.org/about/security-policy/
The code for MariaDB, including all revision history, can be found at: https://github.com/MariaDB/server