… used on joined columns can have a significant impact on the performance of your queries. Take the following example, using the InnoDB storage…, `v` varchar(128) NOT NULL, PRIMARY KEY (`char_id`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8; CREATE TABLE `t2` ( `id` int unsigned NOT…, from 4.33 to 3.12 seconds. This test was performed with MySQL 5.0.67, FreeBSD 7, on a box…
Post: INSERT INTO ... SELECT Performance with Innodb tables.
July 12, 2006 By 22 Comments
Everyone using Innodb tables probably got use to the fact Innodb tables perform non locking reads, meaning unless you use some modifiers such… tables with where clause and joins. It is important for tables which is being read to be Innodb – even if writes are done in MyISAM table. So why was this done, being pretty bad for MySQL Performance and…
Post: Using CHAR keys for joins, how much is the overhead ?
June 18, 2007 By 18 Comments
… integer based join. So how do I read these results ? CHAR keys are indeed slower for joins compared to integer keys Performance degradation can range from few percent to couple of times for Innodb tables MyISAM…
Post: High-Performance Click Analysis with MySQL
December 22, 2008 By 13 Comments
… you can build the functionality you need and get the performance you need. Because I’ve built two such systems to… capacity. What does this have to do with InnoDB? Data clustering. InnoDB‘s primary keys define the physical order rows are… tend to perform well on a data warehousing workload. The nested-loop joins are not all that fast on big joins; the…
Post: Avoiding auto-increment holes on InnoDB with INSERT IGNORE
November 29, 2011 By 8 Comments
… the traditional method changing the innodb_autoinc_lock_mode to 0. But with a loss of performance and concurrency. How can I… problem. A “mutex” table is a clever trick that allows joining tables while keeping them independent of each other in a…`) ) ENGINE=InnoDB; Insert a value using a LEFT OUTER JOIN: insert into foo(name) select 1 from mutex left outer join foo on…
Post: The new cool MySQL patch has landed! Check your queries performance!
October 31, 2007 By 16 Comments
… less than a second as they can also be a performance killer for a busy application. Recently I have started the…_join: No Tmp_table: Yes Disk_tmp_table: No # Filesort: Yes Disk_filesort: No Merge_passes: 0 # InnoDB_IO_r_ops: 19 InnoDB… Full_join: No Tmp_table: No Disk_tmp_table: No # Filesort: No Disk_filesort: No Merge_passes: 0 # No InnoDB statistics available…
Post: Flexviews - part 3 - improving query performance using materialized views
April 4, 2011 By 20 Comments
… mview_table_alias: o mview_join_condition: NULL mview_join_order: 999 *************************** 2. row ***************************…. It is used to prevent wide innodb primary keys on the MV. mysql… difference in response time. Refresh method performance comparison For demonstration purposes, I did …
Post: How well does your table fits in innodb buffer pool ?
December 9, 2010 By 12 Comments
…) bp JOIN innodb_sys_indexes ON id = index_id JOIN innodb_sys_tables ON table_id = innodb_sys_tables.id JOIN innodb_index_stats ON innodb_index_stats.table_name = innodb_sys_tables.name AND innodb… recover. This tool can be also helpful for capacity planning/performance management. In many cases you would learn you need a…
Post: Side load may massively impact your MySQL Performance
November 13, 2011 By 7 Comments
…. It is very typical to hear complains about MySQL interactive performance – serving simple standard web traffic is drastically impacted when some… data_size_mb from innodb_sys_tables as t inner join innodb_sys_indexes as i using(table_id) inner join innodb_buffer_pool_pages… makes workload extremely IO bound hence such drop in performance. The performance of mysqldump is impacted too because we now have 2…
Post: Helgrinding MySQL with InnoDB for Synchronisation Errors, Fun and Profit
November 24, 2011 By 2 Comments
…-5.1.61) and a single test, innodb_plugin.innodb_bug53674. The test is chosen for no …memory after the reset. A speculative processor might perform the read first, which could leave a waiting…state) (sql_show.cc:6238) ==9090== by 0x6A5E0C: JOIN::exec() (sql_select.cc:1863) ==9090== by 0x6A7D72…
