June 18, 2013

Post: Quickly finding unused indexes (and estimating their size)

December 5, 2012 By 2 Comments

…you risk dropping necessary indexes. To accomplish merging multiple result sets, I gathered statistics from both their master and slave… Now we can can see index sizing information in the all_indexes view: mysql> select * from all_indexes\G … *************************** 33. row …

Filed Under: Insight for DBAs, MySQL, Percona Software

Post: Is MySQL 5.6 slower than MySQL 5.5?

February 18, 2013 By 23 Comments

…mysql-socket=/tmp/mysql_sandbox5610.sock –mysql-user=msandbox_rw –mysql-password=msandbox –oltp-table-size…result and I do not think 3% difference will be noticed in most production cases. For benchmark with 64 threads MySQL…

Filed Under: MySQL Tagged With: , , ,

Post: InnoDB Full-text Search in MySQL 5.6: Part 2, The Queries!

March 4, 2013 By 7 Comments

… queries and compare the result sets. Our hope is that the one of two things will happen; either the results returned from a… using MySQL 5.5.30 and MySQL 5.6.10 with no configuration tuning other than to set innodb_ft_min_token_size to… involved. Always test how your application behaves as a result of a major MySQL version upgrade before rolling it into production! Percona…

Filed Under: Insight for DBAs, Insight for Developers, MySQL Tagged With: , , , , ,

Post: How fast can you sort data with MySQL ?

August 18, 2007 By 26 Comments

… see how much MySQL can sort 1.000.000 rows, or rather return top 10 rows from sorted result set which is the… Million of rows/sec. Obviously we can’t get sorted result set faster than that. I placed temporary sort files on tmpfs… buffer sizes. set sort_buffer_size=1000000; mysql> select * from gt order by i desc limit 10; 10 rows in set (0.70 sec) mysql> show…

Filed Under: Benchmarks, Insight for DBAs Tagged With:

Post: Percona XtraDB Cluster: Failure Scenarios with only 2 nodes

July 25, 2012 By 6 Comments

…mysql> select * from percona; +—-+—————+——–+ | id | inserted_from | name | +—-+—————+——–+ | 2 | percona1 | lefred | | 3 | percona2 | kenny | +—-+—————+——–+ 2 rows in set (0.00 sec) percona2 mysql… maximum packet size to 64500, resulting msg size: …

Filed Under: MySQL, XtraDB Cluster

Post: Using any general purpose computer as a special purpose SIMD computer

May 16, 2011 By 5 Comments

…. I inflated the document size significantly to over 3 million “words” by duplicating the entire set multiple times. mysql> load data infile ‘/tmp… buckets and then use intelligent expression substitution to put the results back together, when necessary. When sorting or grouping are used…

Filed Under: MySQL

Post: Ultimate MySQL variable and status reference list

January 8, 2011 By 4 Comments

…MySQL manual, especially the …set_connectionblogpercona.commanual character_set_databaseblogpercona.commanual character_set_filesystemblogpercona.commanual character_set_resultsblogpercona.commanual character_set_serverblogpercona.commanual character_set_systemblogpercona.commanual character_sets…

Filed Under: Insight for DBAs, MySQL

Post: MySQL performance on EC2/EBS versus RDS

August 4, 2011 By 11 Comments

… will cause MySQL to perform slowly or unpredictably. For write-heavy databases, you are generally bound by either the working set size versus the buffer pool size, or the sheer volume of I/O activity… to EBS, even if the working set size is not larger than the buffer pool size. As a result, if you’re going to…

Filed Under: Benchmarks, Cloud and NoSQL, MySQL

Post: Helgrinding MySQL with InnoDB for Synchronisation Errors, Fun and Profit

November 24, 2011 By 2 Comments

…need much introduction, especially to the MySQL server developers. The Valgrind Memcheck …mutex_get_waiters and mutex_set_waiters. Interestingly, there are … 0 bytes inside a block of size 800000 alloc’d ==9090==    at …: handle_select(THD*, st_lex*, select_result*, unsigned long) (sql_select.cc:269) …

Filed Under: MySQL

Post: TPC-H Run on MySQL 5.1 and 6.0

April 10, 2008 By 16 Comments

… from MySQL 6.0 optimizer improvements effort. 100GB Results are more interesting because this is database size for which you can find results published… compared to MySQL results on 10G database. TPC does discourage from comparing results against different database sizes so let’s see 100G data set results. In this case we set cut-off time to 3 hours to give MySQL more…

Filed Under: Benchmarks
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