…the replication topology. On the top-level master, you leave all filters disabled…over the manual’s description of how replication filtering rules are processed. …a clustered filesystem with an external lock manager. You might say that …-tables and insert a few rows into an InnoDB table, but trying to …
Post: How much memory Innodb locks really take ?
July 13, 2006 By 11 Comments
… start with a bit of background – in Innodb row level locks are implemented by having special lock table, located in the buffer pool where small… to lock 1638400 rows, making it less than 3 bits per locked row; Now lets see how much exclusinve locks take: mysql> begin; Query OK, 0 rows…
Post: InnoDB's gap locks
March 27, 2012 By 15 Comments
One of the most important features of InnoDB is the row level locking. This feature provides better concurrency under heavy write load but …. How to troubleshoot gap locks? Is possible to detect those gap locks using SHOW ENGINE INNODB STATUS: —TRANSACTION 72C, ACTIVE 755 sec 4 lock struct…
Post: Innodb Table Locks
July 31, 2012 By 4 Comments
…level locks because innodb will only set intentional level locks for everything by DDL operations. If you’re having locking issues with Innodb chances are it is row level locks…
Post: SELECT LOCK IN SHARE MODE and FOR UPDATE
August 6, 2006 By 51 Comments
… important peices missing in Locking implementation of Innodb are: Lock table Innodb can lock tables but it will still need to set row level locks which is memory… non matched rows Imagine you’re running DELETE FROM USERS WHERE NAME LIKE “%Heikki%”; How any rows do you think will be locked ? Actually…
Post: Innodb undo segment size and transaction isolation
January 12, 2011 By 3 Comments
… can also be bad for other reasons such as taking row level locks which will prevent other transactions for execution, this however only… you set transaction isolation to lowest READ-UNCOMMITTED level Innodb will not purge the rows from undo space until the statement/query is… and Innodb is smart enough to figure how far it can purge the data, it even can be seen in SHOW INNODB STATUS…
Post: SHOW INNODB STATUS walk through
July 17, 2006 By 40 Comments
…stores lock information, adaptive hash indexes and some other system structures. Pending reads and writes are pending requests on buffer pool level. Innodb…last section – row operations which shows activity on the row basics and some system information. It shows innodb thread queue status – how many …
Post: Paul McCullagh answers your questions about PBXT
November 20, 2009 By 2 Comments
…, and how does it compare in performance? Â When would I use PBXT instead of a storage engine like MyISAM, InnoDB or… row has been changed (and is therefore write locked). This means that PBXT does not normally need to maintain long lists of row-level locks… a row-level lock for each row returned by the SELECT. These locks are all stored in RAM. The format is quite compact (especially when row…
Post: MySQL Users Conference - Innodb
May 9, 2007 By 6 Comments
…. It is also rather interesting how is sort file structured for building …Locks Row level replication allows to get relaxed locks in many other cases. Gap or next-key locks…rows if they do not match where clause (think for example about running not-indexed UPDATE which has to lock all rows in Innodb…
Post: Modeling MySQL Capacity by Measuring Resource Consumptions
March 8, 2011 By 1 Comment
… as well as inevitable application specific scalability restrictions, such as row level locks. There is also a load aspect – “random arrivals” tell us… estimates. If we’re running Innodb with MySQL we can use Innodb_data_reads , Innodb_data_writes, Innodb_os_log_fsyncs for your disk… also can be row level locks, etc. The ratio between Wait Time and CPU time is very helpful to see how “wait free your…
