…a limited number of $5 Expo Only passes. Use discount code “KEY” when registering for the Percona Live MySQL … of MySQL 5.6 and its Future in the Cloud”. Moderated by me, the panel will include MySQL industry …on MySQL 5.6 and how MySQL must evolve if it is to remain competitive in the new world order…
Post: Keynotes, BOFs, and the Community Networking Reception at Percona Live MySQL Conference and Expo
April 15, 2013 By 1 Comment
Post: More on MySQL transaction descriptors optimization
April 26, 2013 By Leave a Comment
… in MySQL 5.6, because all SELECT queries in the AUTOCOMMIT mode are, by definition, … is somewhere in between of MySQL 5.5 and MySQL 5.6. In order to understand more about …MySQL 5.6 virtually eliminates contention on the mutex protecting the list of transactions, its applicability is quite limited…
Post: trx descriptors: MySQL performance improvements in Percona Server 5.5.30-30.2
April 12, 2013 By 3 Comments
… orders of magnitudes faster than a list scan. You may be curious if MySQL 5….MySQL transactions created by a non-locking SELECT statement in the autocommit mode. The relevant optimization in MySQL 5… in MySQL 5.6 to achieve even better scalability while removing the read-only limitations. …
Post: Galera Flow Control in Percona XtraDB Cluster for MySQL
May 2, 2013 By 5 Comments
… are copied to all nodes and global ordering is established, but apply and commit is … by the node giving the cluster permission to continue replication. This setting traditionally defaulted to 0.5…master/slave cluster might be: mysql> set global wsrep_provider_options=”gcs.fc_limit=500; gcs.fc_…
Post: Is Synchronous Replication right for your app?
May 14, 2013 By 18 Comments
…MySQL replication from this instance, since MySQL replication is asynchronous. What about semi-sync MySQL…ordering really, really matters (really!). By enforcing replication to all nodes, we can (simultaneously) establish global ordering for the transaction, so by…
Post: ORDER BY ... LIMIT Performance Optimization
September 1, 2006 By 100 Comments
… cause of MySQL Performance problems. Here is what you need to know about ORDER BY … LIMIT optimization to avoid these problems ORDER BY with LIMIT is most… SELECT * FROM sites WHERE category_id=5 ORDER BY date_created DESC LIMIT 10; In this case index by date_created may also work but…
Post: Possible optimization for sort_merge and UNION ORDER BY LIMIT
September 18, 2007 By 10 Comments
… add ORDER BY ORD LIMIT 10 to individual queries. What if we do int manually ? mysql> explain (select * from utest where c1=5 order by ord desc limit 10) union (select * from utest where c2=5 order by ord desc limit 10) order by ord desc limit…
Post: MySQL Indexing Best Practices: Webinar Questions Followup
August 16, 2012 By 4 Comments
… per table in recent MySQL versions. However it is often too many. Instead of thinking about hard limit of indexes I prefer… order by on another column. do i need to add the index on column using order by clause. A: If index is used for ORDER BY… can have equality comparison as a search condition WHERE A=5 ORDER BY B will use index (A,B) for sorting optimization, for…
Post: MySQL 5.6.10 Optimizer Limitations: Index Condition Pushdown
March 14, 2013 By 2 Comments
…What was happening? Well, in order to understand it I…MySQL 5.5. For example, in this case, the actual number of “Handler_read_next” calls was reduced from 8346769 (5.5) to just 266 (5.6), reducing the executing time by almost 5… I would call it a limitation of the current query …
Post: Wow. My 6 year old MySQL Bug is finally fixed in MySQL 5.6
August 30, 2012 By 2 Comments
… fixed in MySQL 5.6.6…. which I reported in Early 2006 (while still being with MySQL) and running MySQL 4.1 … ) ENGINE=MyISAM DEFAULT CHARSET=utf8 mysql> select i,count(*) cnt from trunc group by i order by cnt desc limit 10; +————+——-+ | i | cnt | +————+——-+ | 2147483647 | …
