… with MySQL is troubleshooting memory usage. The problem usually starts like this – you have configured MySQL to use reasonable global buffers, … cache 512619219 (509995888 + 2623331) File system 294352 (82672 + 211680) Lock system 318875832 (318747272 + 128560) Recovery system 0 (0 + 0) Threads …
Post: What MySQL buffer cache hit rate should you target
June 29, 2006 By 5 Comments
… looking for. First thing which needs to be understand is – cache hit ratio can be computed differently for different engines. For… was OS or SAN cache hit rate – something you would not see otherwise. The bad luck is – MySQL currently does not provide… – number of IOs which MySQL needs to do. You better to look at global and local (per thread) numbers and compare them to…
Post: What to tune in MySQL Server after installation
September 29, 2006 By 118 Comments
… for people to work as MySQL DBAs or be involved with MySQL Performance in some way …I’ve seen values over 100.000 used. thread_cache Thread creation/destructions can be expensive, which happen …cache hit ratio is lower than would justify having it enabled. Note: as you can see all of these are global…
Post: MySQL Server Memory Usage
May 17, 2006 By 21 Comments
…_cache_size. If you’re using MyISAM seriously you can also add the size of Operation System cache you would like MySQL to… for your threads. Each thread connecting to MySQL server will needs its own buffers. About 256K is allocated at once even if thread is… Engines. In general storage engines may have their own per thread or global memory allocations which are not tuned as buffers. Watch…
Post: Using Multiple Key Caches for MyISAM Scalability
November 26, 2008 By 8 Comments
… with new Key Cache in MySQL 4.1, and indeed previously it did not even scale with one CPU as global lock was held during IO duration, In MySQL 4.1 the lock is held only when key block (1KB to 4KB) is being copied from Key Cache to thread local…
Post: SHOW INNODB STATUS walk through
July 17, 2006 By 40 Comments
…3396, OS thread id 1148250464, thread declared inside InnoDB 442 mysql tables in use 1, locked 0 MySQL thread id 8079…=2 log writes are done to OS cache, and being sequential writes these logs writes… information. This is by design as requiring global lock to provide consitent information would cause …
Post: How much memory can MySQL use in the worst case?
February 12, 2009 By 17 Comments
…cache and the table cache and the size needed for each thread (thread stack, etc)? Those take memory too. The query cache…there are some “global buffers” that aren’t really global. Suppose you set …Query OK, 0 rows affected (2.34 sec) mysql> select get_lock(@a, 1); +—————–+ | get_lock(@a, 1…
Post: Wanted: Better memory profiling for MySQL
May 18, 2008 By 4 Comments
…_buffer_pool_size) substract memory used by other global buffers such as query_cache_size and key_buffer and will in many… to SHOW STATUS – threads could account statistics for their own memory usage which is when merged together to show GLOBAL status – this… see amount of memory allocated for current thread in addition to global memory allocation. As MySQL is progressing the problem of memory allocation…
Post: Choosing innodb_buffer_pool_size
November 3, 2007 By 39 Comments
… System needs you also have MySQL needs – these include MySQL buffers – query cache, key_buffer, mysql threads, temporary tables, per thread sort buffer which can be… tell you some numbers, for example sum up all your global buffers plus add 1MB for each connection you’re planning…
Post: Heikki Tuuri Innodb answers - Part I
October 26, 2007 By 19 Comments
… also. PZ: memlock already works – it is global MySQL Server option, though it may have problems…_innodb.cc in 5.1: static MYSQL_SYSVAR_ULONG(thread_concurrency, srv_thread_concurrency, PLUGIN_VAR_RQCMDARG, “Helps… you have a battery-backed disk controller cache, then the commit returns in less than …
