… to read it: mysql> set global sort_buffer_size=DEFAULT; Query OK, 0 rows affected (0.00 sec) mysql> select @@global.sort_buffer_size; +—————————+ | @@global.sort_buffer_size | +—————————+ | 2097152… variable global value Right now I can select: mysql> select @@global.sort_buffer_size; +—————————+ | @@global.sort_buffer_size | +—————————+ | 2097152 | +—————————+ 1 row in set (0.00…
Post: Are larger buffers always better ?
June 6, 2006 By 9 Comments
… and some 10 distinct c values. read_buffer_size and read_rnd_buffer_size – These are buffers used by MyISAM to perform reads, in different scenarios. So should… 5 MyISAM will allocate the buffer and populate if fully when MySQL will read only 5 rows from the buffer and throw away the…
Post: Impact of the sort buffer size in MySQL
October 25, 2010 By 8 Comments
… parameter sort_buffer_size is one the MySQL parameters that is far from obvious to adjust. It is a per session buffer that is…. After reading a post from Ronald Bradford (here), I decide to verify and benchmark performance while varying the size of the sort_buffer… 1 1000` do START=`date +%s.%N` OUT=`mysql -e “set session sort_buffer_size=32*1024*$i;select * from sorttest order by…
Post: How much memory can MySQL use in the worst case?
February 12, 2009 By 17 Comments
… “It is possible that mysqld could use up to key_buffer_size + (read_buffer_size + sort_buffer_size)*max_connections”. This was never true — not even when…* 1024 * 100); Query OK, 0 rows affected (2.34 sec) mysql> select get_lock(@a, 1); +—————–+ | get_lock(@a, 1) | +—————–+ | …
Post: New variable slave_max_allowed_packet for slave servers
July 24, 2012 By 2 Comments
One month ago I wrote about how a big read_buffer_size could break the replication. The bug is not solved but … the same problem. First, use a small value for your read_buffer_size (less than max_allowed_packet) and the second one, upgrade… get more information. En Septiembre voy a impartir Formación de MySQL en Madrid (Sep 3-6). Está será la primera vez…
Post: Percona Live: Venu Anuganti; early bird registration expires tomorrow
January 25, 2011 By Leave a Comment
… worked as a database kernel engineer at companies like SolidDB, MySQL, ANTs Data Server and Yahoo! Venu will be presenting on…, and for detailed investigative blog posts such as How read_buffer_size Impacts Write Buffering and Write Performance. — In addition to this announcement, we…
Post: Join Optimizations in MySQL 5.6 and MariaDB 5.5
April 4, 2012 By 4 Comments
… compared to MySQL 5.5 While with join_buffer_size set to 6M and read_rnd_buffer_size set to 6M, the query time for MySQL 5… Name MySQL 5.5 MySQL 5.6 MySQL 5.6 w/ join_buffer_size=6M & read_rnd_buffer_size=6M MariaDB 5.5 MariaDB 5.5 w/ join_buffer_size=6M & mrr_buffer_size…
Post: MySQL 5.6 vs MySQL 5.5 and the Star Schema Benchmark
March 11, 2013 By 7 Comments
…_DATA_READS | 191581 | | INNODB_PAGES_READ | 191570 | | INNODB_ROWS_READ | 910844 | +—————————————+—————-+ 10 rows in set (0.01 sec) mysql> select sq.*, pages / ((@@innodb_buffer_pool_size…_DATA_READS | 186417 | | INNODB_PAGES_READ | 186406 | | INNODB_ROWS_READ | 910844 | +—————————————+—————-+ 10 rows in set (0.00 sec) mysql> select sq.*, pages / ((@@innodb_buffer_pool_size…
Post: Why you should ignore MySQL's key cache hit ratio
February 28, 2010 By 28 Comments
… the key_buffer_size until, when the buffer is full, Key_reads/Uptime reduces to a number you’re comfortable with. Set key_buffer_size really… your IO system’s capabilities. MySQL doesn’t have good instrumentation for scientifically choosing a key_buffer_size setting, but there are many…
Comment: New Forum Categories: Help Wanted, For Hire
March 5, 2013 By 1 Comment
…buffer_size = 8M read_buffer_size = 2M query_prealloc_size = 65536 read_rnd_buffer_size = 8M table_open_cache = 1024 thread_cache_size = 8 query_cache_size = 128M join_buffer_size…
