June 19, 2013

Post: What does Using filesort mean in MySQL?

March 5, 2009 By 27 Comments

…you “what does Using filesort mean in EXPLAIN,” what would you say? I have asked this question in …in memory, so it gets sorted on disk.” Unfortunately, this is not the same thing. First of all, this is Using temporary. Secondly, temporary… How MySQL executes ORDER BY. You can also read about it in …

Filed Under: Insight for Developers Tagged With:

Post: Upgrading MySQL

January 5, 2010 By 24 Comments

…MySQL upgrade two things should normally worry you. It is Regressions – functionality regressions when what you’ve been using before does…MySQL 5.1 with no problems in most cases. When storage type changes, such as DECIMAL field got whole another meaning in MySQL 5.0 MySQL…

Filed Under: Insight for DBAs, MySQL

Post: Zero-Downtime Schema Changes In MySQL

May 3, 2012 By 2 Comments

…what does that mean? Does the tool clean up (i.e., remove table / triggers?) About cleanup.. What…temporary…MySQL bug. Are you sure this is really happening? I would be extremely surprised for such a bug to be happening. In…

Filed Under: Insight for DBAs, MySQL

Post: Can MySQL temporary tables be made safe for statement-based replication?

May 26, 2008 By 8 Comments

… couldn’t be rolled back”, which is interesting.) But does that mean it’s safe for replication? There is one good way…, what‘s logged — not what executes on the master — is what‘s important. In summary, I still don’t see any way to use temporary tables with MySQL statement…

Filed Under: Insight for DBAs Tagged With:

Post: Multi Range Read (MRR) in MySQL 5.6 and MariaDB 5.5

March 21, 2012 By 10 Comments

…in MariaDB 5.5 and not in MySQL 5.6, is that because of a bug in MySQL 5.6 code? As MRR was used in both MySQL…does not actually mean that queries with MRR are performing badly. The interesting thing is that though both MariaDB and MySQL…Using where; Rowid-ordered scan; Using temporary; Using…

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

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

March 4, 2013 By 7 Comments

…in MySQL 5.6: Part 2, The Queries![/caption] This is part 2 in a 3 part series. In…does the speed of InnoDB FTS compare to its MyISAM counterpart, and what kinds of tricks can we use…

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

Post: What to tune in MySQL Server after installation

September 29, 2006 By 118 Comments

…MySQL DBAs or be involved with MySQL Performance in some way is to ask them what should be tuned in MySQL…temporary tables which are created on disk. innodb_buffer_pool_size This is very important variable to tune if you’re using…mean…

Filed Under: Insight for DBAs Tagged With:

Post: How much overhead is caused by on disk temporary tables

August 16, 2007 By 26 Comments

…Using temporary | +—-+————-+——-+——+—————+——+———+——+———+—————–+ 1 row in set (0.01 sec) As you can see I’m using ORDER BY NULL clause as otherwise MySQL…

Filed Under: Benchmarks, Insight for DBAs Tagged With:

Post: How Percona does a MySQL Performance Audit

November 24, 2008 By 17 Comments

…meaning of the output, so it’s clear what…::DBI, which does $dbh->ping …I’ll paste in mysql> show global variables like ‘%table_size%’; +———————+———–+ |…used to determine when an in-memory temporary table will be converted to an on-disk table, which is an expensive operation. In…

Filed Under: Insight for Developers Tagged With:

Post: Enum Fields VS Varchar VS Int + Joined table: What is Faster?

January 24, 2008 By 30 Comments

…in memory in all cases (and dictionary table does too). Second – the rows are relatively short in…in fact it is quite expected – This is MyISAM table which is accessed via index, which means to retrieve each row MySQL…: 1439943 Extra: Using temporary; Using filesort *************************** 2. row …

Filed Under: Benchmarks Tagged With: , , , , , , ,
« Older Posts