MySQL 5.7 Release Notes - Download - MySQL

MySQL 5.7 Release Notes• InnoDB: Heap block debugging information (file_name, lineno), used for logging diagnostics,would appear in release builds. This information should only appear in debug builds. (Bug#16924719, Bug #69422)• InnoDB: Renaming a column while also adding or dropping columns in the same ALTER TABLEoperation would cause an error. (Bug #16864981)• InnoDB: An online ALTER TABLE operation would consume more memory than expected. Duringan online ALTER TABLE operation, an online log buffer containing a head and tail buffer is createdfor each index that is created or rebuilt. The tail buffer is the writer context and is only required forconcurrent write operations on an index while the ALTER TABLE operation is in progress. The headbuffer is the reader context and is only required during the log apply phase. To reduce memoryconsumption, the tail buffer is now allocated when the first DML statement is run on the index, andthe head buffer is only allocated in the log apply phase and freed afterwards. (Bug #16868967, Bug#69325, Bug #17911720)• InnoDB: A type name (srv_shutdown_state) was the same as a variable name. Thesrv_shutdown_state type name has been changed to srv_shutdown_t. (Bug #16735398)• InnoDB: On Windows, the full-text search (FTS) object ID was not in the expected hexadecimalformat. (Bug #16559254)References: See also Bug #16559119.• InnoDB: The buf_buddy_relocate function would perform an unnecessary hash lookup. (Bug#16596057)• InnoDB: Server shutdown would result in a hang with the following message written to the error log:“[NOTE] InnoDB: Waiting for purge thread to be suspended.” (Bug #16495065)• InnoDB: InnoDB would fail to start when innodb_data_file_path specified the data file size inkilobytes by appending K to the size value. (Bug #16287752)• InnoDB: Fetching and releasing pages from the buffer pool and tracking the page state areexpensive and complex operations. Prior to the bug fix, these operations were performed using apage mutex. Using a page mutex to track several things is expensive and does not scale well. Thebug fix separates fetch and release tracking (in-use state) of a page from page I/O state tracking.Fetch and release is now tracked using atomics where available.For portability, a new CMake build option, INNODB_PAGE_ATOMIC_REF_COUNT (default ON), can beused to disable atomic page reference counting on platforms where atomics support is not available.When atomic page reference counting is enabled (default), “[Note] InnoDB: Using atomicsto ref count buffer pool pages” is printed to the error log at server startup. If atomic pagereference counting is disabled, “[Note] InnoDB: Using mutexes to ref count bufferpool pages” is printed instead. (Bug #16249481, Bug #68079)• InnoDB: An insert buffer merge would cause an assertion error due to incorrectly handled ownershipinformation for externally stored BLOBs.InnoDB: Assertion failure in thread thread_num in file ibuf0ibuf.cc line 4080InnoDB: Failing assertion: rec_get_deleted_flag(rec, page_is_comp(page))(Bug #14668683)• InnoDB: Decreasing the auto_increment_increment value would have no affect on the nextauto-increment value. (Bug #14049391, Bug #65225)• InnoDB: Table renaming errors would appear in the LATEST FOREIGN KEY ERROR section of theSHOW ENGINE INNODB STATUS output. (Bug #12762390, Bug #61746)27