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MariaDB server is a community developed fork of MySQL server. Started by core members of the original MySQL team, MariaDB actively works with outside developers to deliver the most featureful, stable, and sanely licensed open SQL server in the industry.
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> ------------------------------------------------------------ > revno: 2791.2.3 > revision-id: joro@sun.com-20090827114042-h55n7qp9990bl6ge > parent: anurag.shekhar@sun.com-20090831073231-e55y1hsck6n08ux8 > committer: Georgi Kodinov <joro@sun.com> > branch nick: B46749-5.0-bugteam > timestamp: Thu 2009-08-27 14:40:42 +0300 > message: > Bug #46749: Segfault in add_key_fields() with outer subquery level > field references > > This error requires a combination of factors : > 1. An "impossible where" in the outermost SELECT > 2. An aggregate in the outermost SELECT > 3. A correlated subquery with a WHERE clause that includes an outer > field reference as a top level WHERE sargable predicate > > When JOIN::optimize detects an "impossible WHERE" it will bail out > without doing the rest of the work and initializations. It will not > call make_join_statistics() as well. And make_join_statistics fills > in various structures for each table referenced. > When processing the result of the "impossible WHERE" the query must > send a single row of data if there are aggregate functions in it. > In this case the server marks all the aggregates as having received > no rows and calls the relevant Item::val_xxx() method on the SELECT > list. However if this SELECT list happens to contain a correlated > subquery this subquery is evaluated in a normal evaluation mode. > And if this correlated subquery has a reference to a field from the > outermost "impossible where" SELECT the add_key_fields will mistakenly > consider the outer field reference as a "local" field reference when > looking for sargable predicates. > But since the SELECT where the outer field reference refers to is not > completely initialized due to the "impossible WHERE" in this level > we'll get a NULL pointer reference. > Fixed by making a better condition for discovering if a field is "local" > to the SELECT level being processed. > It's not enough to look for OUTER_REF_TABLE_BIT in this case since > for outer references to constant tables the Item_field::used_tables() > will return 0 regardless of whether the field reference is from the > local SELECT or not. |
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This is a release of MySQL, a dual-license SQL database server. MySQL is brought to you by the MySQL team at MySQL AB. License information can be found in these files: - For GPL (free) distributions, see the COPYING file and the EXCEPTIONS-CLIENT file. - For commercial distributions, see the LICENSE.mysql file. For further information about MySQL or additional documentation, see: - The latest information about MySQL: http://www.mysql.com - The current MySQL documentation: http://dev.mysql.com/doc Some manual sections of special interest: - If you are migrating from an older version of MySQL, please read the "Upgrading from..." section first! - To see what MySQL can do, take a look at the features section. - For installation instructions, see the Installing and Upgrading chapter. - For the new features/bugfix history, see the Change History appendix. - For the currently known bugs/misfeatures (known errors) see the Problems and Common Errors appendix. - For a list of developers and other contributors, see the Credits appendix. A local copy of the MySQL Reference Manual can be found in the Docs directory in GNU Info format. You can also browse the manual online or download it in any of several formats at the URL given earlier in this file. ************************************************************ IMPORTANT: Bug or error reports should be sent to http://bugs.mysql.com.