… you need to know it is not MySQL problem, might be even not problem with your MySQL configuration, queries and hardware, even… to use. Do push concurrency too high Many developers will test script with multiple level of concurrency and find out doing work… to serve other users too you typically need to reduce concurrency to where it does not overload the system. Unless it…
Post: Benchmarking single-row insert performance on Amazon EC2
May 16, 2012 By 11 Comments
… ENGINE = InnoDB, PARTITION p10 VALUES LESS THAN MAXVALUE ENGINE = InnoDB) */ Also, I ran 5 instances of iiBench simultaneously to simulate 5 concurrent …B+tree, having multiple buffer pool instances to reduce contention problems caused by buffer pool mutexes, using “estimate” checkpoint method …
Post: InnoDB's gap locks
March 27, 2012 By 14 Comments
… of the most important features of InnoDB is the row level locking. This feature provides better concurrency under heavy write load but… have lot of gaps locks in your transactions affecting the concurrency and the performance you can disable them in two different… phantom reads (non repeatable reads) so in order to prevent problems with the replication you should change the binary log format…
Comment: Should you move from MyISAM to Innodb ?
March 10, 2012 By 53 Comments
… that is) and that if not using InnoDB you aren’t too smart. However, InnoDB brings a lot of cons to the… not use MyISAM. If you have a huge number of concurrent writes and selects and query performance must be consistently fast… situations and InnoDB is not the silver bullet that solves all your problems. In fact there are other engines better than InnoDB for…
Post: Heikki Tuuri Innodb answers - Part I
October 26, 2007 By 17 Comments
… of little known aspects of Innodb operations while I see it causing problems every so often. Q16: How Innodb decided how many pages…_innodb.cc in 5.1: static MYSQL_SYSVAR_ULONG(thread_concurrency, srv_thread_concurrency, PLUGIN_VAR_RQCMDARG, “Helps in performance tuning in heavily concurrent…
Post: kernel_mutex problem cont. Or triple your throughput
December 2, 2011 By 10 Comments
…with kernel_mutex problem. First, I may have an explanation why the performance degrades to significantly and why innodb_sync_spin_…innodb_thread_concurrency=8. So now let’s compare results for innodb_thread_concurrency= 0 vs 8 for all range of threads: Threads innodb concurrency=0 innodb concurrency…
Post: InnoDB thread concurrency
June 5, 2006 By 4 Comments
…_innodb–; ENTER; } retry: if (entered_thread < innodb_thread_concurrency) { entered_threads++; thread->n_tickets_to_enter_innodb = innodb_concurrency_tickets; ENTER; } if (innodb_…problems with multiple CPUs is well known bug 15815 so do not think it is considered to be normal behavior. About innodb…
Post: MySQL/Innodb scalability tests after fix
January 3, 2007 By 1 Comment
… still have massive scalability drop with increasing concurrency – going from 10 to 20 concurrent connections drops performance from about 620 to 450… nasty surprise. It may be possible to improve it with innodb concurrency settings though – I do not know, this requires some extra… benchmarks) we can see MySQL scalability problem with high number of CPUs and high concurrency is elevated but it is far from…
Post: MyISAM Scalability and Innodb, Falcon Benchmarks
October 12, 2007 By 10 Comments
We many times wrote about InnoDB scalability problems, this time We are faced with one for MyISAM tables. … we’re getting performance worse than with single query. The problem in this case is key buffer contention which unlike popular… than 2x in peak which happens to be at 4 concurrent threads. So there is still work to do in addition…
Post: My Innodb Feature wishes
May 4, 2006 By 30 Comments
… times space compression. Insert buffer for delete. For Insert operation Innodb uses nice tecnique called Insert Buffer which speeds up inserts… it is so bad I will list it. Basically Innodb has problems scaling both with large number of active threads and with… can see it is too bad even with 4 concurrent queries). The problem seems to be at least partially due to global…
