… from show engine innodb status: —TRANSACTION BB0E42A, ACTIVE 3 sec fetching rows, thread declared inside InnoDB 334 mysql tables in use 4, locked… lock struct(s), heap size 440760, 799203 row lock(s) MySQL thread id 38, OS thread handle 0x2b3c1c776940, query id 16838101…
Post: trx descriptors: MySQL performance improvements in Percona Server 5.5.30-30.2
April 12, 2013 By 3 Comments
…array of active transactions which we call the trx descriptors array. Creating a snapshot of transaction states is …transactions, while a great optimization in itself, applies only to the following kinds of transactions: MySQL transactions started with START TRANSACTION READ ONLY MySQL transactions…
Post: ACTIVE with Locks – Now thats a problem !
June 2, 2011 By 2 Comments
… in ACTIVE state. Especially ACTIVE transactions which do not currently run any query are suspicious. There are however cases when screaming fire about ACTIVE transactions… is when you have long enough ACTIVE transactions which have some locks, like in this case: MySQL thread id 2059, query id 1014425…
Post: Implications of Metadata Locking Changes in MySQL 5.5
February 1, 2013 By 9 Comments
…new column to the table while a transaction in REPEATABLE-READ isolation mode is ACTIVE. session1 > select @@tx_isolation; +—————–+ | @@tx_isolation | +—————–+ | REPEATABLE…this time with how Active MQ uses MySQL when in HA mode. In HA mode there are two Active MQ servers, both …
Post: Product to try: MySQL/MariaDB-Galera 0.8
June 13, 2011 By 34 Comments
… latency of round-trip transactions should be in an acceptable range. It opens the possibility for active master – active master setups. You can… three node cluster is much more complex than an average MySQL master-slave setup. Potential performance penalty: Although to have performance…
Post: How Does Semisynchronous MySQL Replication Work?
January 19, 2012 By 24 Comments
… you commit a transaction, the commit does not complete until all replicas have also committed successfully. In MySQL‘s semi-synchronous replication, the commit completes before the transaction is even sent to any of…. As a result, the effect is that the client’s activity is throttled so that it cannot outpace the replica’s…
Post: Multiple purge threads in Percona Server 5.1.56 and MySQL 5.6.2
May 3, 2011 By 13 Comments
… the subsequent purge work is ensured by a long-running transaction with a REPEATABLE READ isolation level and started WITH CONSISTENT SNAPSHOT. In the middle of the workload this transaction commits and so the purge begins. The tests were performed… activity could be throttled better as to not to penalize further TPS. MySQL 5.6.2 Results Now let’s test MySQL 5…
Post: When does Innodb Start Transaction ?
January 11, 2011 By 9 Comments
… in transaction list. It is only when you read (or write) to INNODB table you can see transaction is started: —TRANSACTION F56AED, ACTIVE 4 sec, process no 23727, OS thread id 139753656395520 MySQL thread id 112, query…
Post: MySQL Error Message Nonsenses
March 16, 2008 By 7 Comments
… kind of error complicating automatic handling. When we tested different transactional storage engines we surely saw lock related tables being far… you have too InnoDB: many active transactions running concurrently? I hope with pluggable storage engine interface Sun/MySQL spends some time to make…
Post: Resyncing table on MySQL Slave
June 29, 2008 By 11 Comments
…’t execute the given command because you have active locked tables or an active transaction) – this is also I used DELETE instead of… having table locked causes connections to pile up and either MySQL runs out of connections or Apache out of children allowed to process request; So you can do following instead: mysql> rename table rep to rep_maint; Query OK, 0 rows…
