… rollback segment, which by default is single and all transactions are serialized accessing to segment. Fortunately InnoDB internally has mechanism to support multiple rollback segments…-1.0.2-pre-release3 with default (1) and 16 rollback segments. For reference MySQL parameters: [mysqld] #mysqld options in alphabetical order…
Comment: Fix of InnoDB/XtraDB scalability of rollback segment
February 25, 2010 By 9 Comments
Just ran into a pileup created by contention on the rollback segment mutex. The thread holding it is blocked on disk IO to read a page from the rollback segment. It doesn’t give up the rollback segment mutex while waiting for IO to complete. That won’t scale. Thanks for finding this.
Post: Innodb undo segment size and transaction isolation
January 12, 2011 By 2 Comments
…’re risking having a lot of “garbage” accumulated in undo segment size which can cause performance degradation as well as increased… record in undo space so row can be deleted on rollback, update and delete however need to put the old row… new blog version is placed in the new location. If rollback is to be performed just on-the-page part of…
Post: Tuning for heavy writing workloads
October 14, 2009 By 9 Comments
… remarkable (it is rseg->mutex). The mutex is for each rollback segments, so we can increase the rsegs to solve the contention… huge size. The value is the number of entries in rollback segment. The entries are used for consistent reading of the older…
Post: 5.0.77 / 5.0.82 -build16 Percona binaries
June 11, 2009 By 4 Comments
… extra user rollback segments created when new db is created. New information_schema table innodb_rseg shows information about all rollback segments innodb_thread…
Comment: Fix of InnoDB/XtraDB scalability of rollback segment
January 25, 2009 By 9 Comments
… compatibility. My group has recommended may times in increasing the rollback segments, but my concern is that in a mixed server environment… will not recover from the new segments defined. Also, giving my.cnf parameter to control segments gives some flexibility but also increases…
Comment: Fix of InnoDB/XtraDB scalability of rollback segment
January 18, 2009 By 9 Comments
… has multiple rollback segments code (but not used). It seems to be stable at least while we use the number of segments statically…
Post: Shard-Query EC2 images available
May 11, 2011 By 2 Comments
…-recovery-update-relay-log innodb-replication-delay=# innodb-rollback-on-timeout innodb-rollback-segments=16 innodb-stats-auto-update=0 innodb-stats-on…
Comment: How InnoDB handles REDO logging
April 20, 2011 By 18 Comments
… handled via the UNDO log (Also referred to as the ROLLBACK segment). UNDO logging being the inverse of REDO, used in the… InnoDB to both support MVCC and provide a mechanism to rollback uncommitted transactions during recovery. >How does innodb keep the consistent…
Comment: How InnoDB handles REDO logging
February 3, 2011 By 18 Comments
… handled via the UNDO log (Also referred to as the ROLLBACK segment). UNDO logging being the inverse of REDO, used in the… InnoDB to both support MVCC and provide a mechanism to rollback uncommitted transactions during recovery. >How does innodb keep the consistent…
