… fact Innodb tables perform non locking reads, meaning unless you use some modifiers such as LOCK IN SHARE MODE or FOR UPDATE… not used you can enable innodb_locks_unsafe_for_binlog option, which will relax locks which Innodb sets on statement execution, which… look in SHOW INNODB STATUS: —TRANSACTION 0 42304626, ACTIVE 14 sec, process no 29895, OS thread id 2894768 updating or deleting mysql tables…
Post: Innodb locking and Foreign Keys
December 12, 2006 By 2 Comments
… details. All Innodb Foreign Key related operations happen on data modification. So for example if you do SELECT FOR UPDATE on CHILD… will try to delete row in PARENT table lockup in CHILD table will be performed with row lock performed. Innodb is smart enough to detect which updates are affecting foreign key relationships. So if you will update any column which…
Comment: InnoDB's gap locks
April 13, 2012 By 15 Comments
… to try to explain the following phrase with an example: “InnoDB provides REPEATABLE READ for read-only SELECT, but it behaves… NULL, `c` char(20) DEFAULT NULL, KEY `i` (`i`) ) ENGINE=InnoDB DEFAULT CHARSET=latin1 mysql> select * from t; +——+——–+ | i | c | +——+——–+ | 1… data, the isolation is READ COMMITED so you can’t update/delete that row, because it doesn’t exist anymore. I hope…
Post: Hijacking Innodb Foreign Keys
January 2, 2012 By 2 Comments
… HardCore MySQL business – foreign Keys. MySQL supported Foreign Keys for Innodb for many years, yet rudimentary support initially added in MySQL… child(parent_id) VALUES(1,”"); set foreign_key_checks=0; delete from parent; After these actions we have child table which…_ley_checks=0) will update references to point to new table, while you can drop Moreover Innodb is very protective when it…
Post: Innodb undo segment size and transaction isolation
January 12, 2011 By 3 Comments
…it is easy to check: mysql> select * from information_schema.innodb_rseg; +———+———-+———-+———+————+———–+ | rseg_id | space_id | zip_size | page_no | …small record in undo space so row can be deleted on rollback, update and delete however need to put the old row …
Post: Efficient Boolean value storage for Innodb Tables
April 23, 2008 By 6 Comments
… delete flag which makes 7 minimum row size MyISAM can have in this configuration. This trick however does not work for Innodb… 00:54:18 Update_time: NULL Check_time: NULL Collation: latin1_swedish_ci Checksum: NULL Create_options: Comment: InnoDB free: 6144 kB… 00:37:48 Update_time: NULL Check_time: NULL Collation: latin1_swedish_ci Checksum: NULL Create_options: Comment: InnoDB free: 4096 kB…
Post: Choosing proper innodb_log_file_size
July 3, 2006 By 12 Comments
… you’re doing significant amount of writes to Innodb tables decent size of innodb_log_file_size is important for MySQL Performance… (random updates will need random IO to check if pages are up to date), number of unflushed pages in innodb buffer pool… reduce “undo” phase is size your transactions appropriately – so updates/inserts/deletes can be sized to affect limited number of rows. Good…
Post: Can Innodb Read-Ahead reduce read performance ?
June 26, 2007 By 2 Comments
… views open inside InnoDB Main thread process no. 3956, id 1157658976, state: sleeping Number of rows inserted 60790248, updated 11571576, deleted 0, read 63850963520 0.00 inserts/s, 0.00 updates/s, 0.00 deletes/s, 24860.96 reads/s The stats are rather interesting. There are 8 queries inside Innodb and…
Post: Heikki Tuuri Innodb answers - Part I
October 26, 2007 By 19 Comments
… you delete a lot of scattered rows you may not see a “free space” in Innodb tablespace to grow significantly. Q6: Does Innodb… MySQL 5.1 Q15: How frequently does Innodb fuzzy checkpointing is activated HT: InnoDB flushes about 128 dirty pages per flush. That…’re waiting you to answer second portion of the questions. UPDATE: Second Part of the answers is now available
Post: MySQL 5.6: Improvements in the Nutshell
January 27, 2013 By 16 Comments
…’ll update the page Scalability – Scalable Read Only Transactions – Concurrent Innodb data file extension – Non-Recursive Deadlock Detection – Faster Locking Primitives – Improved Innodb… for UPDATE/DELETE queries – - JSON output with more information – Optimizer Tracing – Deadlock Logging – GET DIAGNOSTICS Operational Improvements – Separate Tablespaces for Innodb Undo Logs…
