…the bottom of the replication topology. On the top-level master, you leave all filters disabled; on the relay…on top of a clustered filesystem with an external lock manager. You might say that MySQL/NDB Cluster …up with –skip-grant-tables and insert a few rows into an InnoDB table, but trying to run …
Post: MySQL and the SSB - Part 2 - MyISAM vs InnoDB low concurrency
May 22, 2013 By Leave a Comment
… InnoDB performs better when a larger number of rows must be joined together (Q4.1, Q4.2) … there was no caching of data at the filesystem level. The InnoDB indexes were built using ALTER TABLE …_size=32M innodb_buffer_pool_instances=16 metadata_locks_hash_instances=32 table_open_cache_instances=8 …
Post: Innodb Table Locks
July 31, 2012 By 4 Comments
… level locks for everything by DDL operations. If you’re having locking issues with Innodb chances are it is row level locks or auto increment table level lock (mostly with MySQL 5.0 and older MySQL versions). MySQL level locks are entirely different story. Explicitly locking…
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… a consistent Statement based replication. To accomplish that, row level locking databases also acquire gap locks. What is a Phantom Read A Phantom Read…
Post: How much memory Innodb locks really take ?
July 13, 2006 By 11 Comments
… with a bit of background – in Innodb row level locks are implemented by having special lock table, located in the buffer pool where small… locked row. In practice this means memory consumption by row level locks should not be the problem even for rather large databases – even billion of locked rows…
Post: SELECT LOCK IN SHARE MODE and FOR UPDATE
August 6, 2006 By 51 Comments
… 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 and CPU overhead. For some bulk operations it would be more efficient to use table locks. As… are matched by like because locks are taken on Innodb level before MySQL performs like matching, and row is not unlocked if it…
Post: Table locks in SHOW INNODB STATUS
June 8, 2010 By 1 Comment
… table lock on test/t1 table and many people tend to think Innodb in fact in some circumstances would abandon its row level locking and use table locks instead. I’ve seen various theories ranging from lock escalation to using table locks in special…. If Innodb sets intention exclusive lock on the table this means it plans to lock some of the rows in exclusive mode. What…
Post: Paul McCullagh answers your questions about PBXT
November 20, 2009 By 2 Comments
… the Falcon storage engine. PBXT supports row-level locking and foreign keys. Does this create any additional locking overhead that we should be aware… 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…
Comment: COUNT(*) vs COUNT(col)
April 11, 2007 By 45 Comments
… maintain the count of rows since only one transaction executes at any time, because MyISAM does table-level locking. After a transaction commits… table-level locking is a limit on throughput in the presence of updates (including deletes and inserts). However, with InnoDB, which uses row-level locking…
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… separately through number of IOPS) but it also can be row level locks, etc. The ratio between Wait Time and CPU time is… 1us 284s 5ms 13ms 298ms 185us # Lock time 71s 0 3ms 39us 54us 28us 35us # Rows sent 7.15M 0 56.36k…
