… async IO mode. There are two reasons for that. First, MySQL/InnoDB uses async writes, so this will emulate database load… MiB/sec throughput. I may do a wild guess about drops – the drive periodically cleans an internal cache or something. To understand… you are interested more in SSD and MySQL questions – I will be giving a webinary “MySQL and SSD” on May-9. It…
Post: Troubleshooting MySQL Memory Usage
March 21, 2012 By 3 Comments
… Check for Table Cache Related Allocations There are cases when MySQL will allocate a lot of memory for table cache, especially if you… connection. In Percona Server you can do better as you can query temporary tables too: mysql> select sum(data_length+index_length… fact this is often one of the first things I do as it is least intrusive. Run SHOW ENGINE INNODB STATUS…
Post: Join Optimizations in MySQL 5.6 and MariaDB 5.5
April 4, 2012 By 2 Comments
… other possibilities like InnoDB doing read_ahead by noticing the sequential access pattern. BKA is available in both MySQL 5.6 and…’ optimizer_switch=’join_cache_incremental=on’ optimizer_switch=’join_cache_hashed=on’ optimizer_switch=’join_cache_bka=on’ join_cache_level=8 join_buffer… a look at the status counters. Counter Name MySQL 5.5 MySQL 5.6 MySQL 5.6 w/ join_buffer_size=6M & read…
Post: Multi Range Read (MRR) in MySQL 5.6 and MariaDB 5.5
March 21, 2012 By 10 Comments
… secondary index lookups, if the columns that are being fetched do not belong to the secondary index definition (and hence covering… case of MySQL 5.5 and ~5 hours in case of MySQL 5.6 and MariaDB 5.5. Note that query cache is… pattern was sequential and hence InnoDB decided to do read_ahead, while in MySQL 5.5 no read_ahead was done because…
Post: Index Condition Pushdown in MySQL 5.6 and MariaDB 5.5 and its performance impact
March 12, 2012 By 12 Comments
… in preparation for the talk comparing the optimizer enhancements in MySQL 5.6 and MariaDB 5.5. We are taking a… optimizer enhancement Index Condition Pushdown (ICP). Its available in both MySQL 5.6 and MariaDB 5.5 Now let’s take…
Post: MariaDB 5.3 is released as GA!
March 5, 2012 By 17 Comments
…. First, Peter and Ovais are doing a lot of benchmarking of specific MariaDB 5.3 and MySQL 5.6 optimizer improvements, and… key cache for improved scalability That’s really just a sampling. A good starting point for learning more is the MySQL versus… a sane user expects them to do. The new MariaDB release is a great development for MySQL users. Users now have more…
Post: Announcing Percona XtraBackup 1.9.1
February 27, 2012 By 9 Comments
… differentiate beta releases from the final 2.0 release. We do not recommend using Beta releases in production. Link to BETA…. The new xbstream format works with parallel compression to (without caching) stream several compressed files at once. tar4ibd functionality is replaced…
Post: ext4 vs xfs on SSD
March 15, 2012 By 23 Comments
… one more point to consider. Starting the MySQL 5.1 + InnoDB-plugin and later MySQL 5.5 (or equally Percona Server 5…: 97 MiB/sec It corresponds to results I see running MySQL benchmarks (to be published later) on ext4 vs xfs. Actually… prepare sync echo 3 > /proc/sys/vm/drop_caches for numthreads in 4 do sysbench –test=fileio –file-total-size=${size}G…
Post: Should we give a MySQL Query Cache a second chance ?
April 10, 2011 By 63 Comments
… have item invalidated from query cache and there are multiple connection requesting the same item. What MySQL will do ? It will allow all… if it is worth doing or if delayed invalidation is enough. Improve Manageability What is in the MySQL Query Cache ? How many hits… thing about MySQL Query Cache is it knows exactly what is needed to refresh its content and so it can do it automatically…
Post: Query Profiling with MySQL: Bypassing caches
September 12, 2007 By 6 Comments
… bypass these caches? For MySQL Caches you can restart MySQL and this is the only way to clean all of the caches. You can do FLUSH TABLES to clean MySQL table cache (but not Innodb table meta data) or you can do “set global…
