… MB file read. PZ: “often” a bit stikes me here. I thought it would be always single read, typically 1MB in size. I should also mention a post on this topic once. Q12: If read-ahead request… uses it’s own internal buffer pool but it’s in conflict with the Linux kernel’s buffer pool. In high load…
Comment: Database problems in MySQL/PHP Applications
November 6, 2006 By 13 Comments
… open_files_limit = 9216 tmp_table_size=1000M sort_buffer_size = 100M read_buffer_size = 100M read_rnd_buffer_size = 100M myisam_sort_buffer_size = 100M max_length_for_sort_data… #safe-updates [isamchk] key_buffer = 256M sort_buffer_size = 256M read_buffer = 2M write_buffer = 2M [myisamchk] key_buffer = 256M sort_buffer_size = 256M read_buffer = 2M write_buffer = 2M #[mysqlhotcopy] interactive…
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… sort_buffer_size to 128K — I can quite well connect and say “set @@sort_buffer_size := 1 * 1024 * 1024 * 1024;” and my sort_buffer_size is…
Post: Ultimate MySQL variable and status reference list
January 8, 2011 By 4 Comments
….commanual Innodb_buffer_pool_read_aheadblogpercona.commanual Innodb_buffer_pool_read_ahead_evictedblogpercona.commanual Innodb_buffer_pool_read_requestsblogpercona.commanual Innodb_buffer_pool_readsblogpercona.commanual innodb_buffer_pool… rand_seed2blogpercona.commanual range_alloc_block_sizeblogpercona.commanual read_buffer_sizeblogpercona.commanual read_onlyblogpercona.commanual read_rnd_buffer_sizeblogpercona.commanual relay_logblogpercona.commanual relay_log…
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 big, and then measure its size…
Post: A case for MariaDB's Hash Joins
May 31, 2012 By Leave a Comment
…_switch=’mrr_cost_based=off’ read_rnd_buffer_size=32M optimizer_switch=’batched_key_access=on’ join_buffer_size=32M MariaDB 5.5.20 Configuration…_buffer_size‘ controls the size of the join buffer allocated for each join in a query, MariaDB introduces another variable to control the size of…
Post: MySQL Server Variables - SQL layer or Storage Engine specific.
June 8, 2006 By 14 Comments
… MEMORY tables. preload_buffer_size – Buffer used for Key preloading, which works for MYISAM tables only. read_buffer_size, read_rnd_buffer_size – Variables used as read buffer for MyISAM tables for Full Table Scan (read_buffer) and for reading rows in sorted order (read_rnd_buffer_size). Other…
Post: read_buffer_size can break your replication
June 6, 2012 By 12 Comments
… between read_buffer_size and this bug? Again, an example is best than words. These are the new values: max_allowed_packet = 32M read_buffer_size… are based on the read_buffer_size value so they are never larger than the max_allowed_packet 
Therefore, a read_buffer_size value larger than…
Post: MySQL: what read_buffer_size value is optimal ?
September 17, 2007 By 25 Comments
… I’ve discovered even read_buffer_size selection may be less than obvious. What do we generally hear about read_buffer_size tuning ? If you want… performanceread_buffer_sizeTime (sec)820045.216K44.832K45.664K43.4128K43.0256K51.9512K60.82M65.28M66.832M67.2 8200 bytes is the minimum size for read_buffer_size…
Comment: MySQL: what read_buffer_size value is optimal ?
September 21, 2008 By 25 Comments
… in my my.cnf: key_buffer_size = 256M sort_buffer_size = 128K read_buffer_size = 128K read_rnd_buffer_size = 128K join_buffer_size = 128K myisam_sort_buffer_size = 128K and restarted the mysql… to the my.cnf): key_buffer_size 268435456 sort_buffer_size 131064 read_buffer_size 126976 read_rnd_buffer_size 126976 join_buffer_size 126976 myisam_sort_buffer_size 131072 The key_buff shows…
