… if we do not allow MySQL optimizer to use second index and hence index merge, what does it turn to ? It is not combined index but single index on… of combined index in this case. In case you’re using OR between columns – single column indexes are required for index merge to work and combined indexes…
Post: Percona Live MySQL Conference and Expo 2013 – News from the Committee – Tutorial Selection Complete
December 3, 2012 By 1 Comment
…MySQL DBA and would be an excellent choice for anyone either just getting started in MySQL, or who has been doing DBA work… for Creating INDEXes — All about Indexing Now for …not sure when this was not the case at a MySQL conference. There are several MySQL…it’s through our combined effort that we (…
Post: How to find MySQL queries worth optimizing ?
September 11, 2012 By 6 Comments
… also a huge oversimplification. You can do such simple math only to the … to the tables is “const” MySQL does not count it as access to two tables…used in the query. This rule also does not work if you have any group by in the… scans 100x, for example by adding combined index. So what is the easy way …
Post: Why MySQL could be slow with large tables ?
June 9, 2006 By 141 Comments
… different in some respect and what works well for Oracle,MS SQL, PostgreSQL may not work well for MySQL and other way around. Even… or require radom IO if index ranges are scanned. There are also clustered keys in Innodb which combine index access with data access… do not expect joins to be be free. Finally I should mention one more MySQL limitation which requires you to be extra careful working…
Post: How Percona does a MySQL Performance Audit
November 24, 2008 By 17 Comments
…NOT easy to catch, and may require a lot of experience and investigation. The work we do is often not…Indexes and data types and table structures can be changed. Queries can be broken into pieces, combined…
Post: Multi Range Read (MRR) in MySQL 5.6 and MariaDB 5.5
March 21, 2012 By 10 Comments
…index lookups, if the columns that are being fetched do not belong to the secondary index definition (and hence covering index optimization is not…combined size of the secondary key tuples fetched, and N is the buffer size. In MySQL…
Post: MySQL EXPLAIN limits and errors.
July 24, 2006 By 6 Comments
… will in add index live as it can now do on Cluster ? Is it expected to rebuild index by sort … of passes MySQL had to perform and so number of row combinations really examined. LIMIT is not taken into … fields can’t work with in memory temporary table. The other thing – since MySQL 4.1 sorting can …
Post: What to tune in MySQL Server after installation
September 29, 2006 By 118 Comments
…work as MySQL DBAs or be involved with MySQL Performance in some way is to ask them what should be tuned in MySQL… time – it is not rare to see key_buffer being set to 4G while combined size of .MYI … Innodb buffer pool caches both data and index pages so you do not need to leave space for OS cache …
Post: MySQL performance on EC2/EBS versus RDS
August 4, 2011 By 11 Comments
…platform with a RAID of EBS volumes can work well when you do not demand much I/O, either in operations…that I was not able to outstrip RDS 5.1′s performance with the combination of stock MySQL 5.1, EC2,…so all the inserts go into one partition, whose indexes fit in memory. The more elaborate you get …
Post: Finding your MySQL High-Availability solution – The questions
October 16, 2009 By 36 Comments
… not a one size fits all and many deployments use combination of solutions. I will not … since MyISAM is not transactional and do not sync data to disk. Similarly, MySQL replication is an …indexes and GIS indexes that are supported only by MyISAM. The HA solutions that work well with MyISAM are “MySQL…
