… the variable read_rnd_buffer_size, while MariaDB introduces a different variable to control the MRR buffer size mrr_buffer_size. Both buffer sizes default to 256K in MySQL 5…_sort_keys=on’ (only on MariaDB 5.5) optimizer_switch=’mrr_cost_based=off’ read_rnd_buffer_size=4M (only on MySQL 5.6) mrr_buffer_size… optimizer is choosing the query execution plan, is not sufficiently tuned and it is recommended to turn this off. The query…
Post: MySQL: what read_buffer_size value is optimal ?
September 17, 2007 By 25 Comments
… with sort performance and today I’ve discovered even read_buffer_size selection may be less than obvious. What do we generally hear about read_buffer_size tuning… value. Sample my.cnf values on large memory sizes recommend 1M settings and MySQL built-in default is 128K. Some people having…
Post: Choosing innodb_buffer_pool_size
November 3, 2007 By 38 Comments
…size you need to check if there are any restrictions on Innodb Buffer Size…MySQL needs – these include MySQL buffers – query cache, key_buffer, mysql threads, temporary tables, per thread sort buffer…
Post: New SpecJAppServer results at MySQL and Sun.
November 12, 2008 By Leave a Comment
… better to disable them. The MySQL Settings are probably what is the most interesting: MySQL 5.0 Tuning in /etc/my.cnf (included…_cache = 6000 read_rnd_buffer_size = 2M sort_buffer_size = 32k thread_cache = 16 query_cache_size = 0M thread_concurrency = 8 max_heap_table_size=200M log-output…
Post: MySQL Server Memory Usage
May 17, 2006 By 18 Comments
…buffer_size, query_cache_size. If you’re using MyISAM seriously you can also add the size of Operation System cache you would like MySQL…sorts, or need temporary tables as much as read_buffer_size, sort_buffer_size, read_rnd_buffer_size, tmp_table_size…
Post: What to tune in MySQL Server after installation
September 29, 2006 By 116 Comments
…MySQL DBAs or be involved with MySQL Performance in some way is to ask them what should be tuned in MySQL… in normal operation. query_cache_size If your application is read intensive and you do not …simple queries there is no reason to increase sort_buffer_size even if you have 64GB of memory to…
Post: How Percona does a MySQL Performance Audit
November 24, 2008 By 17 Comments
…level of tuning, from … to read. If the InnoDB buffer …mysql> show global variables like ‘%table_size%’; +———————+———–+ | Variable_name | Value | +———————+———–+ | max_heap_table_size | 268435456 | | tmp_table_size… shows all sorts of interesting things…
Post: MySQL Users Conference - Innodb
May 9, 2007 By 6 Comments
…specify compressed block size, this is the size to which you… format for sort used by MyISAM may cause sort files …READ-COMMITED isolation mode which will start offering more performance benefits in MySQL…buffer-pool which had it locking relaxed in latest MySQL… it. Innodb IO Tuning I should also …
Post: table_cache negative scalability
November 16, 2009 By 23 Comments
…). With MySQL common sense however does not always works – we’ve seen performance issues with large query_cache_size also sort_buffer_size and read_buffer_size may not give you better performance if you increase them. I found this also applies to some other buffers… look at it as an absolute number. So if you tune table cache is “normal” case and is able to bring…
Post: Heikki Tuuri Innodb answers - Part I
October 26, 2007 By 17 Comments
…tuning gets it wrong. Q10: When Innodb decides to schedule sequential read-ahead, random read ahead ? HT: InnoDB schedules a sequential read…read, typically 1MB in size. I should also mention a post on this topic once. Q12: If read…buffer pool but some other important parts of MySQL…
