… option you can enable to get fully synchronous replication behavior: mysql> set global wsrep_causal_reads=… great thing is wsrep_causal_reads is session variables so you can mix different applications…default_storage_engine=InnoDB innodb_autoinc_lock_mode=2 innodb_locks_unsafe_for_binlog=1 wsrep_sst…
Post: Understand InnoDB spin waits, win a Percona Live ticket
September 2, 2011 By 2 Comments
…approach to getting a lock on a mutex. First, a thread tries to lock the mutex. If the mutex is locked by…schedule is 100% complete at this time, and the session schedule has two full tracks already with the full…ended. Don’t miss your opportunity to learn about MySQL in London from world-famous …
Post: MySQL Storage Engines - PBXT
May 14, 2007 By 6 Comments
… articles about all storage engines which sessions I attended during MySQL Users Conference but I did not get too far yet, too busy. So today it is time for PBXT. I was very interested about session about… of question about details, such as index structures, buffer management locking implementation and so on. As we already seen in our…
Post: MySQL 5.0, 5.1 and Innodb Plugin CPU Efficiency
December 3, 2008 By 15 Comments
…was taken though it was reached with number of sessions matching number of cores. Just 1 “Data warehourse” … you can see there is some gain for MySQL from read-write lock split patch (found in Percona Builds) … general the more cores we get the more idle CPU we’re getting. It is also very interesting …
Post: MySQL random freezes could be the query cache
March 19, 2009 By 23 Comments
… seem to trigger outages: just tons of simple session requests all hung up for no obvious reason. … 5 minutes at a time, your chance of getting someone logged onto the machine to watch it…two cases mentioned above were caused by scalability/concurrency/locking problems in the query cache. (One was on …
Post: SHOW INNODB STATUS walk through
July 17, 2006 By 40 Comments
… names and lines (which are different in different versions), you get no information what this object is responsible for. You however… length 6 Total number of lock structs in row lock hash table 0 LIST OF TRANSACTIONS FOR EACH SESSION: —TRANSACTION 0 0, not started, process no 3396, OS thread id 1152440672 MySQL…
Post: Paul McCullagh answers your questions about PBXT
November 20, 2009 By 2 Comments
… do any locking. Read locks are not required because each transaction effectively gets its own snapshot of the database. And write locks are not… been running into global locks when calling back into MySQL to do things like open a table, create a session structure (THD) or create a .frm file. One extreme example of this is PBXT recovery. When MySQL calls the…
Comment: Percona XtraDB Cluster reference architecture with HaProxy
June 22, 2012 By 63 Comments
… you lock records in InnoDB with PXC, records are only locked on the local node. Let’s say you open up 2 mysql sessions in HaProxy, and you get to machines 2…’ where id=1, this won’t block on the second session, because you are on a different database instance. However, at…
Post: Using MyISAM in production
June 17, 2006 By 36 Comments
… allocate myisam_sort_buffer_size and MySQL could crash or go swapping. Second – table will be locked while repair is going. If… a lot of such queries to get into trouble. Just one is enough. Lock priorities. By default MySQL treats updates as higher priority… as you see this is where our problems reside. Cache/Session tables (you can throw them away if it server crashes…
Post: Tuning for heavy writing workloads
October 14, 2009 By 9 Comments
…, 667MHz db_STRESS: 32 sessions, RW=1, dbsize = 1000000, no thinktime XtraDB: (mysql-5.1.39 + XtraDB-…most times (it is dict_operation_lock). It may be partition specific lock contention. The current XtraDB … for all cases, sometimes the performance may get worse because of “not proper” or “too much…
