… innodb_read_io_threads = 8 innodb_write_io_threads = 4 innodb_file_per_table = 1 ## Disabling query cache query_cache_size = 0 query_cache… then that, I have also disabled query cache to avoid contention caused by query cache on write heavy workload. OK, so that… I was mostly concerned with write performance, so I went ahead to choose a table structure with no secondary indexes. Other…
Post: Multi Range Read (MRR) in MySQL 5.6 and MariaDB 5.5
March 21, 2012 By 10 Comments
… MySQL 5.6 and MariaDB 5.5. Note that query cache is disabled during these benchmark runs and that the disks…_read_ahead which shows that the access pattern was sequential and hence InnoDB decided to do read_ahead, while in MySQL 5.5 no read_ahead was done because the access pattern was not sequential. Another thing to note is that more read_ahead is done…
Post: Join Optimizations in MySQL 5.6 and MariaDB 5.5
April 4, 2012 By 2 Comments
…_switch=’join_cache_incremental=on’ optimizer_switch=’join_cache_hashed=on’ optimizer_switch=’join_cache_bka=on’ join_cache_level=8 join…read_ahead 1152 23231 130919 23228 130731 131497 Innodb_buffer_pool_read_requests 12947073 10228611 7816154 10251697 9319281 9393396 Innodb_buffer_pool_reads…
Post: Index Condition Pushdown in MySQL 5.6 and MariaDB 5.5 and its performance impact
March 12, 2012 By 12 Comments
I have been working with Peter in preparation for the talk comparing the optimizer enhancements in MySQL 5.6 and MariaDB 5.5. We are taking a look at and benchmarking optimizer enhancements one by one. So in the same way this blog post is aimed at a new optimizer enhancement Index Condition …
Post: Heikki Tuuri answers to Innodb questions, Part II
November 4, 2007 By 13 Comments
… one read-ahead can happen at the same time. How many read-aheads can be waiting in Queue when or Innodb will schedule more read-aheads only when given read-ahead is completed? HT… use about 20 % of the available RAM as its file cache. The ideal configuration in a dedicated server is: set innodb…
Post: Heikki Tuuri Innodb answers - Part I
October 26, 2007 By 17 Comments
…. Q10: When Innodb decides to schedule sequential read-ahead, random read ahead ? HT: InnoDB schedules a sequential read-ahead when it notices an ascending access pattern… no difference. If you have a battery-backed disk controller cache, then the commit returns in less than 100 microseconds. And…
Post: Ultimate MySQL variable and status reference list
January 8, 2011 By 4 Comments
…read_aheadblogpercona.commanual Innodb_buffer_pool_read_ahead_evictedblogpercona.commanual Innodb_buffer_pool_read…
Post: The performance effects of new patches
September 9, 2008 By 14 Comments
… factor 40WH (:=~4GB). It is enough bigger than the data cache of the storage. main common settings innodb_buffer_pool_size… added. innodb_read_ahead (default 3) This controls [enable/disable] of read-ahead. 3: normal 2: enable linear read-ahead only 1: enable random read-ahead only 0… may help the performance. * This test uses “innodb_read_ahead = 0″ (The both of read-ahead are disabled) “innodb_ibuf_contract_const = 50000″ “innodb…
Post: SHOW INNODB STATUS walk through
July 17, 2006 By 40 Comments
… for insert buffer merges, asynchronous log flushes, read-ahead and flushing of dirty buffers. Normal reads originated from query executions are executed by… index scan read-ahead may be performed which can increase average read size significantly. So you can think about this value as read-ahead efficiency…_at_trx_commit=2 log writes are done to OS cache, and being sequential writes these logs writes are pretty fast…
Post: How multiple disks can benefit for single client workload ?
April 26, 2008 By 4 Comments
… read request can only be issued after previous request is completed. Innodb tries to optimize these reads a bit – there is sequential read ahead and random read ahead which are designed to spot data access… continuing. Though in decent systems you have battery backed up cache so this wait is not long. In case innodb_flush…
