…: The research and testing conducted for this post were sponsored by Virident. First, some background information. All tests were conducted on…, the vCache test without time-based flushing still outperforms FlashCache by over 2x, on average. Looking just at sysbench reads, vCache… = 1 innodb_log_file_size = 1G innodb_log_files_in_group = 2 innodb_purge_threads = 1 innodb_fast_shutdown = 1 #not…
Post: Learn About MySQL 5.6 at the Percona Live MySQL Conference
April 3, 2013 By Leave a Comment
… Conference: “MySQL 5.6: Performance Benchmarks, Tuning, and ‘Best’ Practices” by Dmitri Kravtchuk, MySQL Performance Architect “MySQL 5.6: What’s… Bains, Senior Principal Software Engineer “MySQL 5.6: Redefining Replication” by Luís Soares, Senior Software Engineer The Tuesday evening Birds of….6 focus at the Percona Live MySQL Conference. A distinguished group of MySQL experts from HP, Amazon Web Services, Continuent, and…
Post: Percona XtraDB Cluster for MySQL and encrypted Galera replication
May 3, 2013 By 2 Comments
… to me): socket.ssl_cipher = AES128-SHA by default socket.ssl_compression = yes by default Other questions Will IST be encrypted if… Codership, IST transfers use the same socket settings as regular group communication (gcomm). Will SST be encrypted? No, none of the…
Post: Percona Live MySQL Conference 2013 wrap-up
April 29, 2013 By Leave a Comment
… billion within the next few years despite the buzz created by NoSQL alternatives Despite the buzz, MySQL is still much more… Matt Aslett’s summary of 451 Research’s database survey by viewing the research report “451 Research database survey points to… of our multiple service vendors including Ireland Presentations, Carleson Production Group, Tricord, the Hyatt Santa Clara, and the Santa Clara Convention…
Post: MySQL and Percona Server in LinkBench benchmark
May 8, 2013 By 18 Comments
… box with a fast PCI-e flash card as storage. By default linkbench dataset has 10M ids(after load of data…_DIRECT innodb_log_file_size = 2000M innodb_log_files_in_group = 2 innodb_flush_log_at_trx_commit = 1 innodb_log…
Post: Using GROUP BY WITH ROLLUP for Reporting Performance Optimization
September 17, 2007 By 14 Comments
… as group by execution method, not temporary table as ordinary GROUP BY: mysql> explain select grp, count(*) cnt from dt where slack like “a%” group by… forced FileSort execution method for GROUP BY by using SQL_BIG_RESULT hint I can see GROUP BY executing about same time as GROUP BY WITH ROLLUP.
Post: Wrong GROUP BY makes your queries fragile
September 6, 2006 By 7 Comments
… GROUP BY A – what would you expect from such query ? Column A is part of group by so its value is same for whole group… is to stay away from such group by statements, however as usually there are exceptions and such GROUP BY statements may be faster than… GROUP BY id,login May be replaced by SELECT id,login,max(login_time) FROM log GROUP BY id which may be faster especially if GROUP BY…
Post: Should MySQL Extend GROUP BY Syntax ?
August 17, 2007 By 11 Comments
… some value in the group: This is one illustration of group by limitations in SQL language which is not offset by any MySQL specific…, something like SELECT MAX(Population), City, Country FROM City GROUP BY Country GROUPORDER BY Population DESC; This could give you row which has… soring by population you would see MAX(Population) in the population column: SELECT City, Population City FROM City GROUP BY Country GROUPORDER BY Population…
Post: GROUP_CONCAT useful GROUP BY extension
September 4, 2006 By 49 Comments
… the GROUP BY operation: function GROUP_CONCAT: GROUP_CONCAT(expr) – This function returns a string result with the concatenated non-NULL values from a group… | 6 | | 3 | 7 | +—-+———–+ SELECT id,GROUP_CONCAT(client_id) FROM services WHERE id = 3 GROUP BY id; +—-+————————-+ | id | GROUP_CONCAT(client_id) | +—-+————————-+ | 3 | 5…
Post: Speeding up GROUP BY if you want aproximate results
March 7, 2008 By 24 Comments
… sum(cnt) from (select count(*) cnt from performance_log_080306 group by page having cnt>2) pv; Unfortunately this query ran for… sum(cnt) from (select count(*) cnt from performance_log_080306 group by crc32(page) having cnt>3) pv -> ; +———-+ | sum(cnt) | +———-+ | 1127031 | +———-+ 1…
