Wednesday, October 22, 2014

InnoDB BLOB limited by size of redo log

  • Important Change: Redo log writes for large, externally stored BLOB fields could overwrite the most recent checkpoint. The 5.6.20 patch limits the size of redo log BLOB writes to 10% of the redo log file size. The 5.7.5 patch addresses the bug without imposing a limitation. For MySQL 5.5, the bug remains a known limitation.
    As a result of the redo log BLOB write limit introduced for MySQL 5.6, the innodb_log_file_size setting should be 10 times larger than the largest BLOB data size found in the rows of your tables plus the length of other variable length fields (VARCHARVARBINARY, and TEXT type fields). No action is required if your innodb_log_file_sizesetting is already sufficiently large or your tables contain no BLOB data.
    Note
    In MySQL 5.6.22, the redo log BLOB write limit is relaxed to 10% of the total redo log size(innodb_log_file_size * innodb_log_files_in_group).
    (Bug #16963396, Bug #19030353, Bug #69477)